title: Fc-dependent effector functions of idiotype-anti-idiotype immune complexes.
abstract: Some effector functions of antigen-antibody and antibody-antibody (idiotype-anti-idiotype) complexes were analyzed. As a model system a monoclonal IgM antibody specific for the hapten NP (antibody B1-8) was reacted either with hapten and hapten-carrier conjugates or with monoclonal anti-idiotope antibodies with specificity for B1-8 idiotopes. The precipitating, C1q-binding, complement-activating and Fc receptor binding properties of these complexes were compared. Binding of both hapten-carrier conjugates and anti-idiotope antibodies to B1-8 results in formation of complexes which depending on the B1-8:ligand ratio precipitate, activate complement, bind C1q and exhibit increased avidity for Fc mu and Fc gamma receptors of mouse spleen cells. In both types of complexes cross-linking of IgM molecules is essential for triggering these Fc-dependent functions, and a functional heterogeneity if idiotype-anti-idiotope complexes based on different idiotype-anti-idiotope ratios could also be observed. The functional similarity of B1-8-hapten-carrier and B1-8-anti-idiotope complexes suggests that regulatory functions so far assigned to antigen-antibody complexes could be carried out also by idiotype-anti-idiotope complexes.
mesh_terms: D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000276:immunology; D000918:Antibody Specificity; D000936:Antigen-Antibody Complex; D003166:Complement Activating Enzymes / Q000276:immunology; D003167:Complement Activation; D015922:Complement C1q; D006241:Haptens / Q000276:immunology; D006801:Humans; D007130:Immunoglobulin Idiotypes / Q000276:immunology*; D007075:Immunoglobulin M / Q000276:immunology; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D011487:Protein Conformation; D011961:Receptors, Fc / Q000276:immunology*; D012397:Rosette Formation
chemical_list: D000888:Antibodies, Anti-Idiotypic; D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D006241:Haptens; D007130:Immunoglobulin Idiotypes; D007075:Immunoglobulin M; D011961:Receptors, Fc; D015922:Complement C1q; D003166:Complement Activating Enzymes