Mouse monoclonal antibodies at the red cell surface--II. Effect of hapten density on complement fixation and activation.
Complement (C)-dependent hemolytic dose-response curves of anti-TNP IgG2b and IgM monoclonal antibodies as a function of TNP density were analyzed: sheep red cells coupled with TNP served as targets. Under conditions when equal numbers of either IgG2b or IgM anti-TNP antibodies were taken up by cells with various TNP densities, both antibodies showed optimal activity at a hapten density of approximately 10(6) TNP/E with regard to C-mediated lysis. These results were similar to those obtained with polyclonal antibodies. The effectiveness of monoclonal antibodies in utilizing guinea pig or mouse C was also investigated. IgM anti-TNP monoclonal antibodies lysed E-TNP in the presence of guinea pig C, but failed to produce lysis in the presence of mouse C. Two monoclonal IgG1 (anti-TNP and anti-SRBC) and an IgG2a anti-TNP antibody failed to produce hemolysis in the presence of guinea pig and mouse C. IgG2b monoclonal antibodies, whether directed against TNP or Forssman antigen, activated guinea pig and, to a lesser extent, mouse C. Finally, monoclonal anti-TNP IgG3 antibodies exhibited a low but measurable hemolytic activity with guinea pig C (10-20 times below that of IgG2b).
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D003167:Complement Activation; D003172:Complement C1 / Q000276:immunology; D003168:Complement Fixation Tests; D004306:Dose-Response Relationship, Immunologic; D004912:Erythrocytes / Q000276:immunology*; D005577:Forssman Antigen / Q000276:immunology; D006168:Guinea Pigs; D006241:Haptens / Q000276:immunology*; D006461:Hemolysis; D007074:Immunoglobulin G / Q000276:immunology; D007075:Immunoglobulin M / Q000276:immunology; D051379:Mice; D012756:Sheep; D014301:Trinitrobenzenes / Q000276:immunology
D000911:Antibodies, Monoclonal; D003172:Complement C1; D006241:Haptens; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D014301:Trinitrobenzenes; D005577:Forssman Antigen