Polypeptide variants
A variant of a polypeptide comprising a human IgG Fc region is described, which variant comprises an amino acid substitution at one or more of amino acid positions 270, 322, 326, 327, 329, 331, 333 or 334 of the human IgG Fc region. Such variants display altered effector function. For example, C1q binding and/or complement dependent cytotoxicity (CDC) activity may be altered in the variant polypeptide. The application also discloses a variant of a parent polypeptide comprising a human IgG Fc region, which variant has a better binding affinity for human C1q than the parent polypeptide.
1. A process of producing a polypeptide variant comprising culturing a host cell comprising an isolated nucleic acid encoding a variant of a parent antibody or immunoadhesin polypeptide comprising a human IgG Fc region, which variant comprises an amino acid substitution at amino acid position 326, 327, 333 334, or combination thereof of the human IgG Fc region, where the numbering of the residues in the IgG Fc region is that of the EU index as in Kabat.
2. The process of claim 1 further comprising recovering the variant from the host cell culture.
3. The process of claim 1 comprising substitutions at two or more of amino acid positions 326, 327, 333 and 334 of the human IgG Fc region, where the numbering of the residues in the IgG Fc region is that of the EU index as in Kabat.
4. The process of claim 1 wherein the variant comprises an amino acid substitution at amino acid position 326 of the human IgG Fc region.
5. The process of claim 1 wherein the variant comprises an amino acid substitution at amino acid position 327 of the human IgG Fc region.
6. The process of claim 1 wherein the variant comprises an amino acid substitution at amino acid position 333 of the human IgG Fc region.
7. The process of claim 1 wherein the variant comprises an amino acid substitution at amino acid position 334 of the human IgG Fc region.
8. The process of claim 1 wherein the variant comprises an amino acid substitution at amino acid position 326 of the human IgG1 Fc region, where the numbering of the residues in the IgG1 Fc region is that of the EU index as in Kabat.
9. The process of claim 8 wherein the amino acid residue at amino acid position 326 is substituted with valine, glutamic acid, alanine, glycine, aspartic acid, methionine, or tryptophan.
10. The process of claim 9 wherein the amino acid residue at amino acid position 326 is substituted with alanine.
11. The process of claim 9 wherein the amino acid residue at amino acid position 326 is substituted with tryptophan.
12. The process of claim 1 wherein the variant comprises an amino acid substitution at amino acid position 333 of the human IgG1 Fc region, where the numbering of the residues in the IgG1 Fc region is that of the EU index as in Kabat.
13. The process of claim 1 wherein the variant comprises an amino acid substitution at amino acid position 334 of the human IgG1 Fc region, where the numbering of the residues in the IgG1 Fc region is that of the EU index as in Kabat.
14. The process of claim 1 wherein the variant comprises an amino acid substitution at amino acid position 327 of the human IgG1 Fc region, where the numbering of residues in the IgG1 Fc region is that of the EU index as in Kabat
15. The process of claim 1 wherein the variant comprises amino acid substitutions at two or more of amino acid positions 326, 327, 333 and 334 of the human IgG1 Fc region, where the numbering of the residues in the IgG1 Fc region is that of the EU index as in Kabat.
16. The process of claim 1 wherein the variant comprises an antibody.
17. The process of claim 16 wherein the antibody binds an antigen.
18. The process of claim 1 wherein the variant comprises an immunoadhesin.
19. The process of claim 18 wherein the immunoadhesin binds a ligand or receptor.
20. The process of claim 1 wherein the human IgG Fc region is a human IgG1 Fc region.