title: Hemolytic efficiency of cell-bound IgM: evidence that IgM-C1 complexes activate C4 molecules not hemolytic with homologous C2--C9.
abstract: The hemolytic efficiency of rabbit-anti-Forssman IgM antibody depends on the source of complement components. With whole guinea pig complement as few as one in 10 IgM molecules was hemolytic; it was found that with purified guinea pig C1, C4, and C2 components and with rat late-acting components, all IgM molecules were hemolytic. Evidence indicates that the block occurred as a result of generating at least two different cell-bound C4 molecules, one of which was not competent with homologous late-acting components.
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D003167:Complement Activation; D003172:Complement C1 / Q000276:immunology*; D003175:Complement C2 / Q000276:immunology; D003181:Complement C4 / Q000378:metabolism; D005577:Forssman Antigen / Q000276:immunology; D006168:Guinea Pigs; D006461:Hemolysis; D007075:Immunoglobulin M / Q000276:immunology*; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D011947:Receptors, Antigen, B-Cell / Q000276:immunology*
chemical_list: D000906:Antibodies; D003172:Complement C1; D003175:Complement C2; D003181:Complement C4; D007075:Immunoglobulin M; D011947:Receptors, Antigen, B-Cell; D005577:Forssman Antigen