title: Enhancement of lymphocyte-mediated K562 cytotoxicity by antibodies against complement membrane cofactor protein (CD46) and decay-accelerating factor (CD55).
abstract: A natural killer (NK) target, K562 (a human erythroblastoid cell line), was found by flow cytometry to express three complement regulatory membrane proteins on its surface: decay-accelerating factor (DAF, CD55), membrane cofactor protein (MCP, CD46) and p18 (CD59). We examined the effects of F(ab')2 of polyclonal antibodies raised against DAF and MCP and monoclonal antibody to p18 on the susceptibility of K562 to cytolysis by homologous lymphocytes, granulocytes and complement. C3bi-deposition was induced on K562 when the cells were treated with both anti-DAF and anti-MCP. Lymphocyte-mediated K562 cytolysis was markedly enhanced by these two antibodies whereas anti-p18 barely affected the degree of cytolysis. Complement immunocytolysis, on the other hand, became highest by combination treatment with the three antibodies, although anti-p18 and either anti-DAF or anti-MCP induced little potentiation of cytolysis. Granulocytes showed the least cytolysis and minimal potentiation of lysis by treatment with both anti-DAF and anti-MCP.
authors.affiliation: Department of Immunology, Center for Adult Diseases, Osaka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Seya
authors.forename: A
authors.initials: A
authors.lastname: Kojima
authors.forename: T
authors.initials: T
authors.lastname: Hara
authors.forename: K
authors.initials: K
authors.lastname: Hazeki
authors.forename: Y
authors.initials: Y
authors.lastname: Sugita
authors.forename: H
authors.initials: H
authors.lastname: Akedo
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology; D015703:Antigens, CD / Q000276:immunology*; D018958:CD55 Antigens; D002460:Cell Line; D003176:Complement C3 / Q000276:immunology*; D003170:Complement Pathway, Alternative / Q000276:immunology*; D003602:Cytotoxicity, Immunologic / Q000276:immunology*; D005434:Flow Cytometry; D006098:Granulocytes / Q000276:immunology; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology*; D051916:Membrane Cofactor Protein; D008562:Membrane Glycoproteins / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; C497857:CD46 protein, human; D018958:CD55 Antigens; D003176:Complement C3; D051916:Membrane Cofactor Protein; D008562:Membrane Glycoproteins