title: Engineered antibodies with increased activity to recruit complement.
abstract: This manuscript describes two sites in a human IgG1 that, when mutated individually or in combination, result in a dramatic increase in C1q binding and complement-dependent cytotoxicity activity. These two residues, K326 and E333, are located at the extreme ends of the C1q binding epicenter in the C(H)2 domain of a human IgG. A mutation to tryptophan at K326 debilitates Ab-dependent cell-mediated cytotoxicity activity. In addition, substitutions of the residues E333 with serine and of K326 with tryptophan in a human IgG2 confer biological activity in the complement-dependent cytotoxicity assay in which the wild-type IgG2 is inactive. This study reveals that the residues K326 and E333 play a significant role in the control of the biological activity of an IgG molecule and can rescue the activity of an inactive IgG isotype.
authors.affiliation: Oncology Department, Aventis-Gencell, Hayward, CA 94545, USA.
authors.forename: E E
authors.initials: EE
authors.lastname: Idusogie
authors.forename: P Y
authors.initials: PY
authors.lastname: Wong
authors.forename: L G
authors.initials: LG
authors.lastname: Presta
authors.forename: H
authors.initials: H
authors.lastname: Gazzano-Santoro
authors.forename: K
authors.initials: K
authors.lastname: Totpal
authors.forename: M
authors.initials: M
authors.lastname: Ultsch
authors.forename: M G
authors.initials: MG
authors.lastname: Mulkerrin
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics / Q000276:immunology; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology*; D058846:Antibodies, Monoclonal, Murine-Derived; D000920:Antibody-Dependent Cell Cytotoxicity / Q000235:genetics; D018951:Antigens, CD20 / Q000276:immunology / Q000378:metabolism; D001666:Binding Sites, Antibody / Q000235:genetics; D002241:Carbohydrates / Q000032:analysis; D002461:Cell Line, Transformed; D003167:Complement Activation / Q000235:genetics*; D015922:Complement C1q / Q000276:immunology* / Q000378:metabolism*; D018698:Glutamic Acid / Q000235:genetics; D006031:Glycosylation; D006801:Humans; D007074:Immunoglobulin G / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D007132:Immunoglobulin Isotypes / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D008239:Lysine / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D000069283:Rituximab
chemical_list: D000911:Antibodies, Monoclonal; D058846:Antibodies, Monoclonal, Murine-Derived; D018951:Antigens, CD20; D002241:Carbohydrates; D007074:Immunoglobulin G; D007132:Immunoglobulin Isotypes; D018698:Glutamic Acid; D000069283:Rituximab; D015922:Complement C1q; D008239:Lysine