Patent Application
20230203435
This application claims priority from prior Japanese Patent Application No. 2021-181139, filed on Nov. 5, 2021, entitled “Method for producing antibody and antibody”, the entire contents of which are incorporated herein by reference.
The instant application contains a Sequence Listing which has been filed electronically in xml format and is hereby incorporated by reference in its entirety. Said xml copy, created on Nov. 3, 2022, is named SEQ_LIST.xml and is 26.7 KB in size.
The present invention relates to a method for producing an antibody.
There has been known a technique for controlling affinity of an antibody for an antigen by modifying an amino acid sequence of a framework region (FR) while maintaining the amino acid sequence of a complementarity determining region (CDR) of the antibody. FR is a region other than CDRs, present in each variable region of the light chain and heavy chain of the antibody.
For example, U.S. Patent Application Publication No. 2018/0179298 describes a method for controlling affinity for an antigen by changing at least 3 amino acid residues in FR3 of an antibody to charged amino acid residues. The antibody obtained by the method described in U.S. Patent Application Publication No. 2018/0179298 is expected to be used in medicine, an in vitro diagnostic agent, a reagent, and the like.
In order to obtain an antibody in which at least 3 amino acid residues of FR3 are substituted with arginine residues or lysine residues, the present inventors cultured an animal cell into which a gene encoding the antibody had been introduced by a conventional method. However, the amount of the obtained antibody was not sufficiently satisfactory.
The scope of the present invention is defined solely by the appended claims, and is not affected to any degree by the statements within this summary.
Generally, in production of an antibody by a protein expression system using an animal cell, the yield of antibody increases when scale of cell culture is expanded. However, production cost is high. The present inventors have studied a means to increase the yield of antibody regardless of expansion of the scale of cell culture. As a result, the present inventors have found that the yield of antibody is increased by culturing the animal cell into which a gene encoding the antibody is introduced in the presence of a polyanionic compound, thereby completing the present invention.
The present invention provides a method for producing an antibody, comprising culturing in a presence of a polyanionic compound an animal cell into which a gene encoding an antibody has been introduced whereby the animal cell produces the antibody, wherein the polyanionic compound is at least one selected from the group consisting of an anionic polysaccharide and an anionic polyamino acid, and the antibody is an antibody in which at least 3 amino acid residues of framework region 3 (FR3) are substituted each independently with an arginine residue or a lysine residue.
In the method for producing an antibody of the present embodiment, in vitro, an animal cell into which a gene encoding an antibody has been introduced is cultured in the presence of a polyanionic compound so that the animal cell produces an antibody. Here, the antibody encoded by the gene introduced into the animal cell and the antibody produced by the animal cell are antibodies in which at least 3 amino acid residues of FR3 are substituted with arginine residues or lysine residues (hereinafter, also referred to as “variant”).
As used herein, the “antibody” may be any of IgG, IgA, IgM, IgD and IgE, and is preferably IgG. In the case of producing IgG, it is preferable to use an animal cell expression vector in which a gene encoding a full-length light chain and a gene encoding a full-length heavy chain are incorporated as a gene encoding an antibody. The “antibody” may be an antibody fragment. The antibody fragment preferably contains a variable region of a light chain. Examples of such an antibody fragment include Fab, Fab′, F(ab′)2, Fd, Fd′, Fv, scFv, domain antibody (dAb), reduced IgG (rIgG), diabody, triabody, and the like.
An animal cell into which a gene encoding an antibody has been introduced (hereinafter, also referred to as “transgenic cell”) is an animal cell into which the gene has been introduced so that an antibody as a protein can be expressed. The transgenic cell may be, for example, an animal cell in which the gene is incorporated into an intracellular genome, or an animal cell holding the gene as an episomal vector. An animal cell into which a gene encoding an antibody is introduced in such a form is called a stable cell line, and can constitutively express an antibody as a protein. Alternatively, the transgenic cell may be an animal cell transiently expressing an antibody as a protein by transfection of the gene. The antibody expressed by the transgenic cell is secreted from the cell into culture supernatant.
An animal cell is a host cell that expresses a protein by gene transfer. Examples of the animal cell include mammalian cells, insect cells, and the like. Among them, a mammalian cell is particularly preferable. The mammalian cell may be a primary cultured cell prepared from a tissue or an established cell line. Preferably, a mammalian cell line is used. Examples of the cell line include CHO cells (including CHO-K1 and CHO-S), HEK293 cells (including HEK293T and HEK293E), BHK cells, COS cells, HeLa cells, VERO cells, 3T3 cells, and the like. The cell line can be obtained from the American Type Culture Collection (ATCC), the European Collection of Cell Cultures (ECACC), and the like. Commercially available cell lines such as Expi293 (trademark) cell and ExpiCHO (trademark) cell may be used.
The gene encoding an antibody may be incorporated into an animal cell expression vector. The type of animal cell expression vector is not particularly limited, and may be, for example, a plasmid vector, a viral vector, or the like. The gene encoding an antibody includes a gene encoding a light chain of the antibody and a gene encoding a heavy chain of the antibody. When the gene encoding an antibody is incorporated into the animal cell expression vector, the gene encoding a light chain and the gene encoding a heavy chain of the antibody may be incorporated into one vector or may be incorporated into two vectors, respectively.
Introduction of the gene encoding an antibody into an animal cell itself can be performed by a known transfection method. The type of transfection method is not particularly limited, and examples thereof include lipofection method, calcium phosphate co-precipitation method, viral vector method, electroporation method, and the like.
Culture in the presence of a polyanionic compound can be performed, for example, by culturing a transgenic cell in a medium to which the polyanionic compound has been added. By culturing the transgenic cell in the presence of a polyanionic compound, yield of variant by the cell is increased as compared to the case of culturing in the absence of a polyanionic compound. Details of the mechanism by which the yield is increased are not clear, but it is considered that electrostatic interaction between a variant secreted from the transgenic cell into the culture supernatant and the polyanionic compound in the medium contributes. However, the present invention is not bound by a specific theory or the like.
Culture in the absence of a polyanionic compound refers to culturing the transgenic cell in a medium substantially free of a polyanionic compound. The medium substantially free of a polyanionic compound refers to a medium in which the amount of polyanionic compound is small even if the polyanionic compound is contained, and the polyanionic compound is not actively added. Examples of the case where a trace amount of the polyanionic compound is contained in a medium include a case where the polyanionic compound is contained in the additive described later.
The polyanionic compound refers to a polymer having an anionic compound having an anionic functional group as a monomer unit and a salt thereof. Examples of the anionic functional group include a sulfuric acid group, a carboxyl group, and the like. The salt of the polyanionic compound is preferably a pharmaceutically acceptable salt, and examples thereof include sodium salts and potassium salts. In the present embodiment, an anionic polysaccharide and/or an anionic polyamino acid is used as the polyanionic compound. Examples of the anionic polysaccharide include sulfated polysaccharides and alginates. Examples of the anionic polyamino acid include polyglutamic acid, polyaspartic acid, and salts thereof. The polyanionic compound may be one type or two or more types.
Examples of the sulfated polysaccharide include dextran sulfate and salts thereof, glycosaminoglycan, and proteoglycan containing a sulfate group. The dextran sulfate is preferably a pharmaceutically acceptable salt, and examples thereof include sodium salts and potassium salts. Particularly preferred is dextran sulfate sodium.
The alginate is preferably a pharmaceutically acceptable salt of alginic acid, and examples thereof include sodium alginate, potassium alginate, and ammonium alginate. Among them, sodium alginate is particularly preferable.
The glycosaminoglycan refers to an acidic polysaccharide containing an amino sugar. Examples of the glycosaminoglycan include heparin, heparan sulfate, chondroitin sulfate, dermatan sulfate, keratan sulfate, pentosan sulfate, and salts thereof. Chondroitin sulfate has various structures depending on the type of sugar as a constituent and the position of the sulfate group. Examples of the type of chondroitin sulfate include chondroitin sulfate A (chondroitin 4-sulfate), chondroitin sulfate C (chondroitin 6-sulfate), chondroitin sulfate D (chondroitin 6-sulfate having a sulfate group at position 2 of glucuronic acid), chondroitin sulfate E (chondroitin sulfate having sulfate groups at positions 4 and 6 of N-acetylgalactosamine), and the like. Chondroitin sulfate B is the same as dermatan sulfate. In the present embodiment, any chondroitin sulfate may be used.
The salt of glycosaminoglycan is preferably a pharmaceutically acceptable salt, and examples thereof include sodium salts and potassium salts. Particularly preferred is a sodium salt. In the present embodiment, it is preferable to use heparin sodium, sodium heparan sulfate, sodium chondroitin sulfate, sodium dermatan sulfate, sodium keratan sulfate, or sodium pentosan sulfate. Among them, heparin sodium and sodium chondroitin sulfate are particularly preferably used.
The proteoglycan refers to a compound in which glycosaminoglycan and a protein are covalently bonded. Examples of the proteoglycan containing a sulfate group include proteins in which any one selected from heparin, heparan sulfate, chondroitin sulfate, dermatan sulfate, keratan sulfate, and salts thereof is covalently bonded. Such proteins are known per se and include, and examples thereof include aggrecan, versican, neurocan, brevican, decorin, biglycan, syndecan, glypican, and the like.
The anionic polyamino acid preferably contains a plurality of acidic amino acids. The acidic amino acid contained in the anionic polyamino acid is any one or both of glutamic acid and aspartic acid. The anionic polyamino acid may include a neutral amino acid and/or a basic amino acid, but when the anionic polyamino acid includes a basic amino acid, the number of residues of the basic amino acid is less than the number of residues of the acidic amino acid. The anionic polyamino acid preferably does not contain a basic amino acid and more preferably consists only of acidic amino acids. The anionic polyamino acid may be any of a polymer composed of L-form amino acids, a polymer composed of D-form amino acids, and a polymer containing both L-form and D-form amino acids. The anionic polyamino acid salt is preferably a pharmaceutically acceptable salt, and examples thereof include sodium salts and potassium salts. Particularly preferred are sodium polyglutamate and sodium polyaspartate.
The average molecular weight of the dextran sulfate sodium may be about 5,000 or more and about 500,000 or less. As used herein, the “average molecular weight” is a weight average molecular weight measured by gel permeation chromatography (GPC). When a commercially available polyanionic compound is used, the molecular weight of the compound may be a value disclosed by a manufacturer or a supplier.
The lower limit of the concentration of the polyanionic compound in the medium is preferably higher than 0.01 mg/mL. The lower limit of the concentration may be, for example, 0.02 mg/mL, 0.03 mg/mL, 0.04 mg/mL, 0.05 mg/mL, 0.06 mg/mL, 0.07 mg/mL, 0.08 mg/mL, 0.09 mg/mL, or 0.1 mg/mL. The upper limit of the concentration of the polyanionic compound in the medium is not particularly limited, but is, for example, 20 mg/mL or less. The upper limit of the concentration may be, for example, 19 mg/mL, 18 mg/mL, 17 mg/mL, 16 mg/mL, 15 mg/mL, 14 mg/mL, 13 mg/mL, 12 mg/mL, 11 mg/mL, or 10 mg/mL. For example, the transgenic cell can be cultured in a medium containing the polyanionic compound at a concentration of 0.05 mg/mL or more and 20 mg/mL or less, and more preferably at a concentration of 0.1 mg/mL or more and 10 mg/mL or less.
The polyanionic compound may be added to the medium in advance or may be added to the medium from the middle of cell culture. When the transgenic cell is a stable cell line, it is preferable to culture in a medium to which a polyanionic compound has been added in advance. When the transgenic cell is a cell transiently expressing an antibody by transfection, it is preferable to add the cell to the medium, for example, 3 to 4 hours after completion of the gene introduction operation. Alternatively, the medium may be replaced with a medium to which the polyanionic compound has been added in advance.
Culture period is not particularly limited, and can be appropriately determined according to, for example, the type of animal cell, the type of protein expression system, a culture method, and the like. When the animal cell is a stable cell line, the culture period may be, for example, 5 days or more and 14 days or less. When the animal cell transiently expresses a variant by transfection of a gene encoding a variant, the culture period may be, for example, 24 hours or more and 7 days or less from the completion of the gene introduction operation.
The medium is not particularly limited, and examples thereof include a medium generally used for culturing an animal cell in vitro. Such a medium itself is known, and examples thereof include MEM, DMEM, RPMI-1640, and the like. In addition, a commercially available medium such as CD FortiCHO (trademark) medium or Expi293 (trademark) Expression medium may be used. If necessary, additives such as fetal bovine serum (FBS), L-glutamine, antibiotics, antifungal agents and anti-agglutinating agents may be mixed in the medium. When the transgenic cell is a stable cell line into which a gene expressing a selection marker such as a drug resistance gene has been introduced, it is preferable to add a selection agent to the medium. Selection markers and corresponding selection agents are known.
As culture conditions for an animal cell, known conditions may be adopted depending on the type of cell and the like. For example, a general mammalian cell can be cultured under the condition of 37° C. under a 5% CO2 atmosphere. In addition, a culture method may be selected according to the scale of culture. Examples of the culture method include batch culture, fed-batch culture, and continuous culture. The continuous culture includes chemostat culture and perfusion culture. The batch culture is suitable, for example, for small-scale culture at laboratory level. The fed-batch culture and the continuous culture are suitable, for example, for large-scale culture at industrial level.
When the method for producing an antibody of the present embodiment is carried out by batch culture, a medium containing the transgenic cell and the polyanionic compound is added to a culture vessel or a culture apparatus, and the medium was cultured. Hereinafter, the culture vessel or the culture apparatus containing the transgenic cell cultured in the medium containing the polyanionic compound is also referred to as “culture system”. In the batch culture, supply of the medium into the culture system and removal of the cell culture (cell and medium) out of the culture system are not performed during the culture period. When the method for producing an antibody of the present embodiment is carried out by fed-batch culture, a medium containing the transgenic cell and the polyanionic compound is added to a culture vessel or a culture apparatus, and the medium was cultured. During the culture period, predetermined components (medium component, nutrient source, the additive described above, polyanionic compound, and the like) are continuously or intermittently supplied into the culture system. When the method for producing an antibody of the present embodiment is carried out by chemostat culture, the medium is continuously supplied to a culture vessel or a culture apparatus to which the medium containing the transgenic cell and the polyanionic compound has been added. At this time, the same amount of cell culture as the supplied medium is continuously taken out of the culture system to maintain the culture system in a steady state. When the method for producing an antibody of the present embodiment is carried out by perfusion culture, the medium is continuously supplied to a culture vessel or a culture apparatus to which the medium containing the transgenic cell and the polyanionic compound has been added. At this time, the same amount of culture supernatant as the supplied medium is continuously taken out of the culture system to maintain the culture system in a steady state. In the perfusion culture, the cell is not removed.
The culture vessel or the culture apparatus can be appropriately selected according to the type of cell, the culture method, and the like. Examples of the culture vessel include a dish, a microplate, a culture flask (T-flask), a spinner flask, a roller bottle, and the like. Examples of the culture apparatus include a stirred bioreactor, a fluidized bed bioreactor, a fixed bed culture vessel, and the like.
After culturing the transgenic cell in the presence of a polyanionic compound in vitro, the produced variant is recovered from the culture supernatant or the cell. Since the variant expressed by the transgenic cell is usually secreted to the outside of the cell, the variant is present in the culture supernatant. Therefore, by removing the cell from the cell culture and recovering only the culture supernatant, a solution of the variant can be obtained. When a part of the variant expressed by the transgenic cell is accumulated in the cell, a solution of the variant can be obtained by lysing the cell with a solution containing an appropriate solubilizing agent to liberate the variant. If necessary, the lysate of the cell may be centrifuged to recover the supernatant containing the variant. The variant liberated in the liquid may be purified by a known method such as gel filtration chromatography or affinity chromatography.
In the method for producing an antibody of the present embodiment, the yield of variant is increased as compared with the yield of variant obtained by culture in the absence of a polyanionic compound. On the other hand, the function of the variant produced in the present embodiment as an antibody is equivalent to that of the variant obtained by culture in the absence of a polyanionic compound. For example, the affinity of a variant obtained by the method for producing an antibody of the present embodiment for an antigen is the same as that of a variant obtained by culture in the absence of a polyanionic compound. The affinity for an antigen can be evaluated by, for example, an immunological measurement method such as an ELISA method, a kinetic parameter in an antigen-antibody reaction, or the like. Examples of an index of affinity by immunological measurement include a 50% effective concentration (EC50). Examples of the kinetic parameter include dissociation constant (KD), binding rate constant (kon), and dissociation rate constant (koff). The kinetic parameter in an antigen-antibody reaction can be obtained by surface plasmon resonance (SPR) technology or the like. Hereinafter, the variant will be described.
As long as the variant obtained by the method for producing an antibody of the present embodiment is an antibody in which at least 3 amino acid residues of FR3 are substituted with arginine residues or lysine residues, the antigen recognized by the variant, the animal species from which the variant is derived, and the like are not particularly limited. Here, FR is a region other than CDRs, present in each variable region of the light chain and heavy chain of the antibody. FR plays a role of a scaffold linking three CDRs and contributes to structural stability of the CDR. Therefore, the amino acid sequence of FR is highly conserved between antibodies of the same species. Each variable region of the heavy chain and light chain has three CDRs, CDR1, CDR2 and CDR3, and four FRs, FR1, FR2, FR3 and FR4. These are arranged in the order of FR1, CDR1, FR2, CDR2, FR3, CDR3 and FR4 from the N-terminal side of the variable region.
The variant may be, for example, an antibody derived from human, mouse, rat, hamster, rabbit, goat, horse, or chicken. The variant may be a chimeric antibody, a humanized antibody, a bispecific antibody, or the like.
In the variant, since at least 3 amino acid residues of FR3 are substituted with arginine residues or lysine residues, the affinity of the variant for an antigen is improved as compared with the antibody before the substitution. Hereinafter, an antibody before at least 3 amino acid residues of FR3 are substituted with arginine residues or lysine residues is also referred to as “original antibody”. Substituting at least 3 amino acid residues of FR3 of the original antibody with arginine residues or lysine residues is hereinafter also referred to as “modify”. The variant may be an antibody described in U.S. Patent Application Publication No. 2018/0179298. U.S. Patent Application Publication No. 2018/0179298 is incorporated herein by reference.
In the present embodiment, the variant is preferably an antibody in which at least 3 amino acid residues of the light chain FR3 are substituted with arginine residues or lysine residues. In one embodiment, in the variant, at least 3 amino acid residues of FR3 substituted with arginine residues or lysine residues includes residues at at least three positions selected from the group consisting of positions 63, 65, 67, 70 and 72 of a light chain defined by the Chothia method. For example, in the light chain FR3 of the variant, positions that are arginine residues or lysine residues may be any of the following (1) to (5):
(1) positions 63, 65 and 67 of the light chain defined by the Chothia method;
(2) positions 65, 67 and 70 of the light chain defined by the Chothia method;
(3) positions 63, 65, 67 and 70 of the light chain defined by the Chothia method;
(4) positions 65, 67, 70 and 72 of the light chain defined by the Chothia method; and
(5) positions 63, 65, 67, 70 and 72 of the light chain defined by the Chothia method.
The Chothia method is known as one of methods of numbering the amino acid residues of CDR (hereinafter, also referred to as “numbering method”) for defining boundary and length of CDR. When the amino acid residues of CDR are numbered by the numbering method, the amino acid residues of FR are also numbered. The number assigned to the amino acid residue by the numbering method indicates a position of the amino acid residue in the amino acid sequence of the light chain or the heavy chain. In the present specification, boundaries and lengths of CDR and FR3 are defined by Chothia method (see Chothia C. and Lesk A M., Canonical Structures for the Hypervariable Regions of Immunoglobulins., J Mol Biol., vol. 196, pp. 901-917, 1987). In the Chothia method, the light chain FR3 is defined as a region consisting of amino acid residues at positions 57 to 88 of the light chain. Hereinafter, when the position of an amino acid residue in the light chain of an antibody is described, the position of the amino acid residue means a position defined by the Chothia method unless otherwise specified.
In the variant, amino acid residues other than positions 63, 65, 67, 70 and 72 of the light chain, for example, amino acid residues selected from positions 57 to 62, 74, 76, 77 and 79 to 81 of the light chain may be arginine residues or lysine residues. Here, positions 57 to 62, 74, 76, 77 and 79 to 81 of the light chain are positions of amino acid residues excluding the Vernier zone residue and the unexposed residue from the amino acid sequence of the light chain FR3. The term “Vernier zone residue” is an amino acid residue contributing to structural stability of the CDR among the amino acid sequence of FR. The term “unexposed residue” is an amino acid residue that is folded inside the molecule and is not exposed to the surface.
In the variant, amino acid residues after being modified from amino acid residues of the original antibody may be all arginine residues or all lysine residues. Alternatively, a part of the amino acid residues after being modified from the amino acid residues of the original antibody may be arginine residues, and the rest may be lysine residues.
In the present embodiment, the electrical characteristic of CDR of the variant is preferably neutral or negatively charged. As used herein, the “electrical characteristic of CDR” is determined by following formula (I):
X=[Number of basic amino acid residues in amino acid sequence of CDR contained in one antigen binding site]−[Number of acidic amino acid residues in amino acid sequence of CDR contained in one antigen binding site] formula (I)
wherein when X is −2 or less, the electrical characteristic of CDR is negatively charged,
when X is −1, 0 or 1, the electrical characteristic of CDR is neutral, and
when X is 2 or more, the electrical characteristic of CDR is positively charged.
The “one antigen binding site” is a site composed of one heavy chain variable region and one light chain variable region, and is a site that binds to an antigen in an antibody. The number of antigen binding sites of an antibody varies depending on class and form of the antibody. For example, when an antibody is IgG or F(ab′)2, the antibody has two antigen binding sites. When an antibody is Fab, the antibody has one antigen binding site. The “CDR contained in one antigen binding site” is all CDRs present in one heavy chain variable region and one light chain variable region constituting the one antigen binding site. That is, the CDR contained in one antigen binding site is a total of six CDRs of CDR1, CDR2 and CDR3 in one heavy chain variable region and CDR1, CDR2 and CDR3 in one light chain variable region.
As can be seen from the formula (I), the electrical characteristic of CDR is determined based on the number of acidic amino acid residues and basic amino acid residues in the amino acid sequence of CDR contained in one antigen binding site. When X calculated by the formula (I) is −2 or less, that is, when the number of acidic amino acid residues is larger than the number of basic amino acid residues by 2 or more, in the amino acid sequence of CDR contained in one antigen binding site, the electrical characteristic of CDR is determined to be negatively charged. Also, when X calculated by the formula (I) is −1, 0, or 1, that is, when the difference between the number of acidic amino acid residues and the number of basic amino acid residues is 0 or 1, in the amino acid sequence of CDR contained in one antigen binding site, the electrical characteristic of CDR is determined to be neutral.
In other words, when the total number of acidic amino acid residues contained in the six CDRs of the light chain CDR1, the light chain CDR2, the light chain CDR3, the heavy chain CDR1, the heavy chain CDR2 and the heavy chain CDR3 is larger than the total number of basic amino acid residues by 2 or more, the electrical characteristic of CDR is defined to be negatively charged. In addition, when the difference between the total number of acidic amino acid residues contained in the six CDRs of the light chain CDR1, the light chain CDR2, the light chain CDR3, the heavy chain CDR1, the heavy chain CDR2 and the heavy chain CDR3 and the total number of basic amino acid residues is 0 or 1, the electrical characteristic of CDR is defined to be neutral. As used herein, the acidic amino acid residues are an aspartic acid residue and a glutamic acid residue, and the basic amino acid residues are an arginine residue and a lysine residue. As used herein, a histidine residue is not included in the basic amino acid residues.
A gene encoding a variant can be acquired using known DNA recombination techniques and other molecular biological techniques, for example, with reference to
U.S. Patent Application Publication No. 2018/0179298. First, a polynucleotide encoding the amino acid sequence of the original antibody is obtained. For example, when there is a hybridoma that produces an original antibody, RNA extracted from the hybridoma is used to synthesize a polynucleotide encoding the light chain of the original antibody and a polynucleotide encoding the heavy chain, by a reverse transcription reaction and a RACE (Rapid Amplification of cDNA ends) method. Next, from these polynucleotides, a polynucleotide encoding an amino acid sequence in which the light chain FR3 and/or the heavy chain FR3 is modified is prepared. For example, the polynucleotide encoding the light chain of the original antibody as a template is amplified by PCR using a primer for modifying at least 3 amino acid residues of light chain FR3, whereby a polynucleotide encoding the light chain in which FR3 has been modified can be obtained. The obtained polynucleotide and the polynucleotide encoding the heavy chain of the original antibody can be used as genes encoding a variant. If necessary, the gene encoding a variant may be incorporated into an animal cell expression vector.
When there is no hybridoma that produces the original antibody, an antibody-producing hybridoma may be prepared by known methods such as those described in, for example, Kohler and Milstein, Nature, vol. 256, pp.495-497, 1975. Alternatively, the polynucleotide encoding the light chain and the polynucleotide encoding the heavy chain of the antibody may be synthesized using RNA obtained from the spleen of an animal such as a mouse immunized with an antigen of interest. Alternatively, an amino acid sequence of an antibody that specifically binds to an antigen of interest or a base sequence of an antibody gene may be acquired from a known database, and gene synthesis may be performed based on these sequences to acquire an antibody gene. Examples of the database include GeneBank, abYsis, IMGT, and the like.
Hereinbelow, the present invention will be described in detail by examples, but the present invention is not limited to these examples.
An animal cell into which a gene encoding rituximab and its variant was introduced was cultured in a medium containing a saccharide or a sulfated polysaccharide, and whether the yield of antibody was increased was studied.
(1) Acquisition of Gene of Variant of Rituximab
In the same manner as in the method described in U.S. Patent Application Publication No. 2018/0179298, a polynucleotide encoding the light chain of rituximab, its R3 variant and its R5 variant was synthesized by PCR using a plasmid DNA containing a gene encoding rituximab (mouse/human chimeric antibody) as a template. In addition, a polynucleotide encoding the heavy chain of rituximab was synthesized. The R3 variant was an antibody in which amino acid residues at positions 63, 65 and 67 of the light chain defined by the Chothia method were substituted with arginine residues. The R5 variant was an antibody in which amino acid residues at positions 63, 65, 67, 70 and 72 of the light chain defined by the Chothia method were substituted with arginine residues. A polynucleotide encoding the light chain of each variant and a polynucleotide encoding the heavy chain of rituximab were inserted into a Freedom (trademark) pCHO 1.0 Expression Vector (Thermo Fisher Scientific Inc.). Thus, an animal cell expression plasmid DNA containing a gene encoding each variant of rituximab was obtained. In addition, an animal cell expression plasmid DNA containing a gene encoding rituximab in which the amino acid residue of the light chain FR3 is not substituted was also obtained.
Based on the base sequence of the gene encoding rituximab, amino acid sequences of a light chain and a heavy chain of the antibody (IgG) were determined. These amino acid sequences were as follows. Also, the amino acid sequences of the light chains of each prepared variant (IgG) are also shown below. The underlined portion indicates a position substituted with an arginine residue.
(2) Introduction of Gene Encoding Antibody into Animal Cell
[Reagents]
CHO-S Cells (Thermo Fisher Scientific Inc.)
CD FortiCHO (trademark) medium (Thermo Fisher Scientific Inc.)
Anti-aggregation agent (Thermo Fisher Scientific Inc.)
OptiPRO (trademark) SFM (Thermo Fisher Scientific Inc.)
FreeStyle (trademark) MAX reagent (Thermo Fisher Scientific Inc.)
L-Glutamine (Thermo Fisher Scientific Inc.)
Puromycin dihydrochloride (Thermo Fisher Scientific Inc.)
Methotrexate hydrate (Sigma-Aldrich)
CHO-S cells were proliferated by shaking culture (130 rpm) in a CD FortiCHO (trademark) medium containing 8 mM L-glutamine under 8% CO2 atmosphere at 37° C. and 85% humidity. 30 mL of cell culture (1.0×106 cells/mL) was prepared according to the number of samples. Plasmid DNAs encoding each of rituximab, R3 variant and R5 variant were cleaved with restriction enzyme Pvu I and purified by an ethanol precipitation method to obtain linearized plasmid DNA. A DNA solution having the following composition was prepared using linearized plasmid DNA. Also, a transfection reagent having the following composition was prepared, and the transfection reagent was left for 5 minutes.
The prepared DNA solution and transfection reagent were mixed. The mixture was allowed to stand for 10 minutes. The resulting mixture (3 mL) was added to the cell culture (30 mL). The mixture was shake-cultured (150 rpm) at 37° C. in a 5% CO2 atmosphere. After 48 hours, puromycin and methotrexate were added to each culture, and selection of cells into which the gene had been introduced was performed. The medium was replaced and passaged until viability and cell proliferation capability were restored, thereby obtaining CHO-S cells stably expressing rituximab and each variant (hereinafter referred to as “stable cell line”). Cultures of these stable cell lines were cryopreserved by a conventional method.
(3) Culture of Stable Cell Lines
Each cryopreserved stable cell line was thawed and cultured in a CD FortiCHO (trademark) medium containing 1/100 amount of an anti-aggregation agent and 8 mM L-glutamine, and passaging was performed multiple times. A test medium was prepared by adding a saccharide or a sulfated polysaccharide to a CD FortiCHO (trademark) medium containing 8 mM L-glutamine. As a saccharide, D(+) glucose (FUJIFILM Wako Pure Chemical Corporation), sucrose (KISHIDA CHEMICAL CO.,LTD.), or trehalose dihydrate (FUJIFILM Wako Pure Chemical Corporation) was added so as to have a concentration of 50 mM. As a sulfated polysaccharide, sodium chondroitin sulfate C (FUJIFILM Wako Pure Chemical Corporation), dextran sulfate sodium (molecular weight: 5000) (Merck KGaA), or heparin sodium (FUJIFILM Wako Pure Chemical Corporation) was added so as to have a concentration of 1 mg/mL. Each passaged stable cell line was centrifuged at 800 rpm for 5 minutes to completely remove the medium. Each recovered stable cell line was seeded on each test medium at a concentration of 3.0×105 cells/mL, followed by culturing for 14 days. For comparison, each stable cell line was cultured for 14 days in a medium to which a saccharide and a sulfated polysaccharide were not added.
(4) Evaluation of Survival and Antibody Production of Stable Cell Lines
A part of the cell culture was collected as a specimen at the start of culture (Day 0) and on Days 3, 7, 10 and 14 from the start in each test medium. A part of the specimen was used to count living cells and dead cells. In addition, the specimen was centrifuged, and antibody concentration in the supematant was measured. Cell counting was performed using a hemocytometer after staining the cells with trypan blue. For each stable cell line, viability was calculated from the number of living cells and the number of dead cells. The antibody concentration in the supematant was measured by sandwich ELISA method. Specific operations were as follows.
A solution of an anti-human IgG Fc antibody (Bethyl Laboratories, Inc.) diluted to 2 μg/mL with a KPL coating solution (SeraCare Life Sciences, Inc.) was added to each well of a 96-well plate (Coming Inc.), and the plate was incubated at 4° C. ovemight. After removing the solution from each well, 1% BSA/PBS was added, and the plate was incubated at room temperature for 3 hours. The solution was removed from each well, and then the plate was washed three times with 0.1% Tween (registered trademark) 20-containing PBS (PBST). A culture supernatant was added to each well, and the plate was incubated at room temperature for 1 hour. The solution was removed from each well, and then the plate washed three times with PBST. A solution of an HRP-labeled anti-human IgG Fc antibody (Bethyl Laboratories, Inc.) diluted to 0.3 pg/mL with 1% BSA/PBS was added to each well, and the plate was incubated at room temperature for 1 hour. The solution was removed from each well, and then the plate washed three times with PBST. Chromogenic reaction was performed using KPL
ABTS (registered trademark) Peroxidase Substrate System (SeraCare Life Sciences, Inc.), and the chromogenic reaction was stopped using KPL ABTS (registered trademark) Peroxidase Stop Solution (SeraCare Life Sciences, Inc.). Absorbance at 405 nm was measured using a SpectraMax (registered trademark) 190 microplate reader (Molecular Devices, LLC). The concentration of the antibody in each supematant was obtained using a standard curve of a reference antibody.
(5) Results
The viability (%) of each stable cell line cultured in a medium to which a saccharide or a sulfated polysaccharide has been added is shown in
As shown in
As shown in
As shown in
Each of the stable cell lines of rituximab and R5 variant prepared in Example 1 was cultured in a medium containing dextran sulfate sodium at various concentrations or molecular weights, and whether the yield of antibody was increased was studied.
(1) Culture of Stable Cell Lines
Frozen stocks of each of the stable cell lines of rituximab and R5 variant were thawed, cultured, and passaged in the same manner as in Example 1. In order to study the molecular weight, a test medium was prepared by adding dextran sulfate sodium (Merck KGaA) with a molecular weight of 5,000 or dextran sulfate sodium (FUJIFILM Wako Pure Chemical Corporation) with a molecular weight of 50,000 to a CD FortiCHO (trademark) medium containing 8 mM L-glutamine so as to have a concentration of 1 mg/mL. In addition, in order to study the concentration, a test medium was prepared by adding dextran sulfate sodium (Merck KGaA) with a molecular weight of 5,000 to a CD FortiCHO (trademark) medium containing 8 mM L-glutamine so as to have a concentration of 0.1, 1 or 10 mg/mL. In the same manner as in Example 1, each stable cell line was seeded on each test medium, followed by culturing for 11 or 12 days. For comparison, each stable cell line was cultured for 11 or 12 days in a medium to which dextran sulfate sodium had not been added.
(2) Evaluation of Survival and Antibody Production of Stable Cell Lines
For the experiment of the test medium containing dextran sulfate sodium at different concentrations, a part of the cell culture was collected as a specimen at the start of culture (Day 0) and on Days 4, 7, 9 and 11 from the start. For the experiment of the test medium containing dextran sulfate sodium with different molecular weights, a part of the cell culture was collected as a specimen at the start of culture (Day 0) and on Days 5, 7, 9 and 12 from the start. In the same manner as in Example 1, the cell viability was calculated, and the antibody concentration in the supernatant was measured.
(3) Results
The viability (%) of each of the stable cell lines of rituximab and R5 variant in the test medium containing dextran sulfate sodium at different concentrations are shown in
As shown in
As shown in
The stable cell line of R3 variant of rituximab prepared in Example 1 was cultured in a medium containing dextran sulfate sodium of various molecular weights, and whether the yield of antibody was increased was studied.
(1) Culture of Stable Cell Lines
A frozen stock of the stable cell line of R3 variant was thawed, cultured and passaged in the same manner as in Example 1. In the same manner as in Example 2, a test medium was prepared by adding dextran sulfate sodium (Merck KGaA) with a molecular weight of 5,000, dextran sulfate sodium (FUJIFILM Wako Pure Chemical Corporation) with a molecular weight of 50,000 or dextran sulfate sodium (FUJIFILM Wako Pure Chemical Corporation) with a molecular weight of 500,000 to a CD FortiCHO (trademark) medium containing 8 mM L-glutamine so as to have a concentration of 1 mg/mL. In the same manner as in Example 1, each stable cell line was seeded on each test medium, followed by culturing for 12 days. For comparison, each stable cell line was cultured for 12 days in a medium to which dextran sulfate sodium had not been added.
(2) Evaluation of Survival and Antibody Production of Stable Cell Lines
A part of the cell culture was collected as a specimen at the start of culture (Day 0) and on Days 5, 7, 9 and 12 from the start. In the same manner as in Example 1, the cell viability was calculated, and the antibody concentration in the supernatant was measured.
(3) Results
The viability (%) of the stable cell line of R3 variant is shown in
Each of the stable cell lines of rituximab and R5 variant prepared in Example 1 was cultured in a medium containing heparin sodium at various concentrations, and whether the yield of antibody was increased was studied.
(1) Culture of Stable Cell Lines
Frozen stocks of each of the stable cell lines of rituximab and R5 variant were thawed, cultured, and passaged in the same manner as in Example 1. In the same manner as in Example 2, to a CD FortiCHO (trademark) medium containing 8 mM L-glutamine, heparin sodium (FUJIFILM Wako Pure Chemical Corporation) was added so as to have a concentration of 0.1, 1 or 10 mg/mL to prepare a test medium. In the same manner as in Example 1, each stable cell line was seeded on each test medium, followed by culturing for 12 days. For comparison, each stable cell line was cultured for 12 days in a medium to which heparin sodium had not been added.
(2) Evaluation of Survival and Antibody Production of Stable Cell Lines
A part of the cell culture was collected as a specimen at the start of culture (Day 0) and on Days 5, 7, 9 and 12 from the start. In the same manner as in Example 1, the cell viability was calculated, and the antibody concentration in the supernatant was measured.
(3) Results
The viability (%) of each of the stable cell lines of rituximab and R5 variant is shown in
As shown in
An animal cell into which a gene encoding rituximab and its variant was introduced was cultured in a medium containing sodium polyaspartate or sodium polyglutamate as an anionic polyamino acid, and whether the yield of antibody was increased was studied.
(1) Culture of Stable Cell Lines
Frozen stocks of each of the stable cell lines of rituximab, R3 variant and R5 variant were thawed, cultured, and passaged in the same manner as in Example 1. Sodium poly-(α,β)-DL-aspartate (Merck KGaA) or sodium poly-L-γ-glutamate (Merck KGaA) was added to a CD FortiCHO (trademark) medium containing 8 mM L-glutamine so as to have a concentration of 1 mg/mL to prepare a test medium. In the same manner as in Example 1, each stable cell line was seeded on each test medium, followed by culturing for 12 days. For comparison, each stable cell line was cultured for 12 days in a medium to which an anionic polyamino acid had not been added.
(2) Evaluation of Survival and Antibody Production of Stable Cell Lines
A part of the cell culture was collected as a specimen at the start of culture (Day 0) and on Days 5, 7, 9 and 12 from the start. In the same manner as in Example 1, the cell viability was calculated, and the antibody concentration in the supernatant was measured.
(3) Results
The viability (%) of each of the stable cell lines of rituximab, R3 variant and R5 variant are shown in
An animal cell into which a gene encoding rituximab and its variant was introduced was cultured in a medium containing dextran as a neutral polysaccharide, and whether the yield of antibody was increased was studied. For comparison, an experiment using a medium containing dextran sulfate sodium as an anionic polysaccharide was also performed.
(1) Culture of Stable Cell Lines
Frozen stocks of each of the stable cell lines of rituximab, R3 variant and R5 variant were thawed, cultured, and passaged in the same manner as in Example 1. Dextran (molecular weight 5,000) (Sigma-Aldrich) or dextran sulfate sodium (molecular weight 5,000) (Sigma-Aldrich) was added to a CD FortiCHO (trademark) medium containing 8 mM L-glutamine so as to have a concentration of 1 mg/mL to prepare a test medium. In the same manner as in Example 1, each stable cell line was seeded on each test medium, followed by culturing for 12 days. For comparison, each stable cell line was cultured for 12 days in a medium to which any polysaccharide had not been added.
(2) Evaluation of Survival and Antibody Production of Stable Cell Lines
A part of the cell culture was collected as a specimen at the start of culture (Day 0) and on Days 2, 7 and 12 from the start. In the same manner as in Example 1, the cell viability was calculated, and the antibody concentration in the supernatant was measured.
(3) Results
The viability (%) of each of the stable cell lines of rituximab, R3 variant and R5 variant are shown in
As shown in
An animal cell into which a gene encoding rituximab and R3 variant was introduced was cultured in a medium containing alginate as an anionic polysaccharide without a sulfate group or polyproline as a neutral polyamino acid, and whether the yield of antibody was increased was studied.
(1) Culture of Stable Cell Lines
Frozen stocks of each of the stable cell lines of rituximab and R3 variant were thawed, cultured, and passaged in the same manner as in Example 1. Sodium alginate 80-120 (FUJIFILM Wako Pure Chemical Corporation) or poly-L-proline (Sigma-Aldrich) was added to a CD FortiCHO (trademark) medium containing 8 mM L-glutamine so as to have a concentration of 1 mg/mL to prepare a test medium. In the same manner as in Example 1, each stable cell line was seeded on each test medium, followed by culturing for 12 days. For comparison, each stable cell line was cultured for 12 days in a medium to which a polysaccharide and an anionic polyamino acid had not been added.
(2) Evaluation of Survival and Antibody Production of Stable Cell Lines
A part of the cell culture was collected as a specimen at the start of culture (Day 0) and on Days 5, 7, 9 and 12 from the start. In the same manner as in Example 1, the cell viability was calculated, and the antibody concentration in the supernatant was measured.
(3) Results
The viability (%) of each of the stable cell lines of rituximab and R3 variant is shown in
As shown in
An animal cell into which a gene encoding variants of various antibodies other than rituximab was introduced was cultured in a medium containing a sulfated polysaccharide, and whether the yield of antibody was increased was studied. In this example, a transient expression system was used. The affinity of each antibody for an antigen was also evaluated.
(1) Acquisition of Genes of Variants of Various Antibodies Other than Rituximab
In the same manner as the method described in U.S. Patent Application Publication No. 2018/0179298, a polynucleotide encoding a light chain of each antibody and its variant was synthesized by PCR using a plasmid DNA containing a gene encoding each of trastuzumab (humanized antibody), an anti-lysozyme antibody (mouse antibody), an anti-IL-6 antibody (mouse/human chimeric antibody) and an anti-IL-8 antibody (mouse/human chimeric antibody) as a template. In addition, a polynucleotide encoding the heavy chain of each antibody was synthesized. Variants of trastuzumab and the anti-IL-8 antibody were R3 variant and R4 variant. Variants of the anti-lysozyme antibody and the anti-IL-6 antibody were R5 variants.
The R3 variant of trastuzumab was an antibody in which amino acid residues at positions 65, 67 and 70 of the light chain defined by the Chothia method were substituted with arginine residues, and the R4 variant was an antibody in which amino acid residues at positions 63, 65, 67 and 70 of the light chain defined by the Chothia method were substituted with arginine residues. The R3 variant of the anti-IL-8 antibody was an antibody in which amino acid residues at positions 63, 65 and 67 of the light chain defined by the Chothia method were substituted with arginine residues, and the R4 variant was an antibody in which amino acid residues at positions 63, 65, 67 and 70 of the light chain defined by the Chothia method were substituted with arginine residues. The R5 variants of the anti-lysozyme antibody and the anti-IL-6 antibody were antibodies in which amino acid residues at positions 63, 65, 67, 70 and 72 of the light chain defined by the Chothia method were substituted with arginine residues.
A polynucleotide encoding the light chain of each antibody variant was inserted into pcDNA3.4 vector (Thermo Fisher Scientific Inc.). Thus, an animal cell expression plasmid DNA containing genes encoding the light chains of various antibodies and their variants (hereinafter, also referred to as “light chain plasmid”) was obtained. In addition, a polynucleotide encoding the heavy chain of each antibody was inserted into the pcDNA3.4 vector to obtain an animal cell expression plasmid DNA containing a gene encoding the heavy chain of each antibody (hereinafter, also referred to as “heavy chain plasmid”). In order to evaluate the affinity for an antigen, using the animal cell expression plasmid DNA of rituximab and its R3 and R5 variants prepared in Example 1, light chain plasmids of rituximab and its R3 and R5 variants and a heavy chain plasmid of rituximab were also prepared.
Based on the base sequence of the gene encoding each antibody, amino acid sequences of a light chain and a heavy chain of the antibody (IgG) were determined. These amino acid sequences were as follows. Also, the amino acid sequences of the light chains of each prepared variant (IgG) are also shown below. The underlined portion indicates a position substituted with an arginine residue.
RLNIHPMEEDDSAMYFCQQSKEVPWTFGGGTKLEIKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKV
(2) Introduction of Gene Encoding Antibody into Animal Cell and Cell Culture
[Reagents]
Expi293 (trademark) Cells (Thermo Fisher Scientific Inc.)
Expi293 (trademark) Expression medium (Thermo Fisher Scientific Inc.)
ExpiFectamine (trademark) 293 transfection kit (Thermo Fisher Scientific Inc.)
(2.1) Transfection
Expi293 (trademark) Cells were proliferated by shaking culture (150 rpm) at 37° C. in a 5% CO2 atmosphere. 25.5 mL of cell culture (3×106 cells/mL) was prepared according to the number of samples. A DNA solution with the following composition was prepared using a light chain plasmid and a heavy chain plasmid. The DNA solution was allowed to stand for 5 minutes.
A transfection reagent having the following composition was prepared. The transfection reagent was allowed to stand for 5 minutes.
The prepared DNA solution and the transfection reagent were mixed. The mixture was allowed to stand for 20 minutes. The resulting mixture (3 mL) was added to cell culture (25.5 mL) to perform transfection into cells. The transfected cells were shake-cultured (125 rpm) at 37° C. for 4 hours in a 5% CO2 atmosphere. Dextran sulfate sodium (molecular weight: 5000) (Sigma-Aldrich) was added to the cell culture so as to have a concentration of 1 mg/mL, and the mixture was further subjected to shaking culture. For comparison, the cell culture to which dextran sulfate sodium had not been added was similarly shaken and cultured. After 20 hours after transfection, 150 μL and 1.5 mL of ExpiFectamine (trademark) transfection enhancers 1 and 2 were added to the cell culture, respectively. Each mixture was shake-cultured (125 rpm) at 37° C. for 4 days in a 5% CO2 atmosphere. Culture supernatant was collected from each cell culture 5 days after transfection.
(3) Evaluation of Antibody Production
A part of the recovered culture supernatant was taken as a sample for measuring the antibody concentration. The concentration of each antibody in the culture supernatant was measured by sandwich ELISA method. Rituximab, trastuzumab, an anti-IL-6 antibody and an anti-IL-8 antibody were measured in the same manner as in Example 1. The anti-lysozyme antibody as a mouse antibody was measured as follows.
A solution of goat anti-mouse IgG (H+L) Highly Cross-Adsorbed (Thermo Fisher Scientific Inc.) diluted to 5 μg/mL with a KPL coating solution (SeraCare Life Sciences, Inc.) was added to each well of a 96-well plate (Corning Inc.), and the plate was incubated at 4° C. overnight. After removing the solution from each well, 1% BSA/PBS was added, and the plate was incubated at room temperature for 3 hours. The solution was removed from each well, and then the plate washed three times with PBST. A culture supernatant was added to each well, and the plate was incubated at room temperature for 1 hour. The solution was removed from each well, and then the plate washed three times with PBST. A solution of HRP-labeled goat F(ab′)2 fragment anti-mouse IgG (H+L) (Beckman Coulter, Inc.) diluted to 0.3 μg/mL with 1% BSA/PBS was added to each well, and the plate was incubated at room temperature for 1 hour. The solution was removed from each well, and then the plate washed three times with PBST. Chromogenic reaction was performed using KPL TMB (registered trademark) Peroxidase Substrate (SeraCare Life Sciences, Inc.) and the chromogenic reaction was stopped using KPL TMB (registered trademark) Peroxidase Stop Solution (SeraCare Life Sciences, Inc.). Absorbance at 450 nm was measured using a SpectraMax (registered trademark) 190 microplate reader (Molecular Devices, LLC). The concentration of the antibody in each supernatant was obtained using a standard curve of a reference antibody.
(4) Evaluation of Affinity of Modified Antibody for Antigen
(4.1) Purification of Antibody
An antibody in a culture supernatant recovered from the cell culture to which dextran sulfate sodium had been added was purified using MabSelect (trademark) (Cytiva). The resulting antibody solution was further purified by gel filtration chromatography using Superdex (registered trademark) 200 Increase 10/300 GL (Cytiva). PBS was used as a mobile phase, and purification was performed under the condition of a flow rate of 0.75 mL/min. The antibody concentration in the antibody solution obtained by purification was calculated by measuring the absorbance at 280 nm.
(4.2) Biotin Labeling of Trastuzumab and its Variant
Trastuzumab and its R3 and R4 variants were labeled with biotin using Biotin Labeling Kit-NH2 (DOJINDO LABORATORIES). Specific operations were carried out according to the package insert of the kit.
(4.3) Measurement of Affinity for Antigen
The affinity of each antibody for an antigen was measured by ELISA method. As antigens of each antibody, human CD20/MS4A1 full-length protein, His tag (HEK293) (ACROBiosystems Inc.), recombinant human ErbB2/Her2 Fc chimera (R&D Systems Inc.), chicken egg white-derived lysozyme (Sigma-Aldrich), animal free recombinant human IL-6 (PeproTech Inc.) and interleukin 8 (CXCL8) (Shenandoah Biotechnology, Inc.) were used. Specific operations are as follows. A solution of various antigens diluted to 5 μg/mL with PBS was added to each well of a 96-well plate (Nunc), and the plate was incubated at 4° C. overnight. After removing the solution from each well, 1% BSA/PBS was added, and the plate was incubated at room temperature for 3 hours. The solution was removed from each well, and then the plate washed three times with PBST. An antibody solution was added to each well, and the plate was incubated at room temperature for 15 minutes. The solution was removed from each well, and then the plate washed three times with PBST. A solution of HRP-labeled anti-human IgG Fc antibody (Bethyl Laboratories, Inc.), HRP-labeled goat F(ab′)2 fragment anti-mouse IgG (H+L) (Beckman Coulter, Inc.) or HRP-conjugated streptavidin (Thermo Fisher Scientific Inc.) diluted to 0.3 μg/mL with 1% BSA/PBS was added to each well, and the plate was incubated at room temperature for 1 hour. The solution was removed from each well, and then the plate washed three times with PBST. Chromogenic reaction was performed using KPL TMB (registered trademark) Peroxidase Substrate (SeraCare Life Sciences, Inc.) and the chromogenic reaction was stopped using KPL TMB (registered trademark) Peroxidase Stop Solution (SeraCare Life Sciences, Inc.). Absorbance at 450 nm was measured using a SpectraMax (registered trademark) 190 microplate reader (Molecular Devices, LLC).
(5) Results
Expression levels and affinity for antigens of antibodies of other than rituximab and their variants are shown in Tables 1 to 4 and
As shown in Tables 1 to 4, the yields of trastuzumab, anti-lysozyme antibody, anti-IL-6 antibody and anti-IL-8 antibody were almost the same even when dextran sulfate sodium had been added as compared to those in the case where dextran sulfate sodium had not been added. On the other hand, the yields of variants of antibodies were clearly increased by the addition of dextran sulfate sodium as compared to those in the case where dextran sulfate sodium had not been added. In the variants of the antibodies, while it is common that a predetermined amino acid residue of the light chain FR3 is substituted with an arginine residue, the amino acid sequences of the light chain and the heavy chain are different from each other. Therefore, it was suggested that the effect of increasing the yields of variants by the polyanionic compound can be applied to variants of any antibody. In addition, as shown in Tables 1 to 5 and
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-181139 | Nov 2021 | JP | national |
