Anti-idiotype antibodies to anti-mitochondrial antibodies in the sera of patients with primary biliary cirrhosis.

Idiotype-anti-idiotype interactions were investigated in the sera of patients with primary biliary cirrhosis (PBC), which is characterized by the presence of circulating anti-mitochondrial antibodies (AMA). A mouse monoclonal antibody, CPZ674, has been raised to the E2 component of the pyruvate dehydrogenase complex (PDC), which is the target antigen of AMA. CPZ674 recognizes one of the epitopes recognizable by AMA, as demonstrated by competitive Western blotting. Anti-idiotypic antibodies in PBC sera were detected either by their specific binding to CPZ674 in an ELISA or by the formation of idiotype-anti-idiotype complexes with CPZ674, detected using chromatography on a Sephacryl-300 column and by a polyethylene glycol precipitation method. The specificity of the anti-idiotypic antibodies to AMA was shown by their ability to inhibit the binding of AMA to PDC, but not the binding of other autoantibodies to their relevant autoantigens. We have therefore produced evidence for the existence of idiotype-anti-idiotype interactions in PBC, but whether these anti-idiotypic antibodies are involved in the control of AMA is unknown.