ACTIVATION OF MOUSE COMPLEMENT BY DIFFERENT CLASSES OF MOUSE ANTIBODY

Abstract

The capacity of mouse Ig[immunoglobulin]M, IgG1, IgG2 and IgA anti-dinitrophenyl (DNP) antibodies to activate mouse or guinea pig complement [C] was studied using a sensitive hemolytic assay and 2-dimensional immunoelectrophoresis to detect cleavage of mouse C3. Three monoclonal IgM antibodies and a heterogeneous IgM fraction lysed trinitrophenylated erythrocytes in the presence of guinea pig C, but failed to produce lysis in the presence of mouse C, and only activated mouse C3 very inefficiently. A monoclonal IgG1 antibody did not produce hemolysis in the presence of guinea pig or mouse C, but cleaved mouse C3 via the alternative pathway. Two IgA myeloma proteins (M315 and M460) had similar properties. A heterogeneous IgG2 antibody fraction produced hemolysis in the presence of mouse and guinea pig C and activated the classical and alternative pathways of mouse C.