Discrimination by rabbit anti-idiotypic antibodies of two murine IgM monoclonal antibodies directed against lipid A

Abstract

Two murine IgM monoclonal antibodies (MAs) directed against the lipid A portion of bacterial lipopolysaccharide (LPS) were compared in their binding to Re LPS and lipid A and their idiotypic make-up with rabbit anti-idiotypic sera. Horseradish peroxidase (HRPO)-labelled MAs 8-2 and 26-20 bound equally well to Re LPS. The binding of HRPO-labelled MA 8-2 to synthetic lipid A was low compared to the relatively strong binding of labelled 26-20. The MAs proved to be competitive in a competition binding assay (CBA) with Re LPS as coating antigen. Rabbit immune sera were raised against individual MAs. Anti-idiotypic antibodies (anti-id Abs) were detected with two sensitive enzyme immunoassays (EIA): a solid-phase EIA and an inhibition EIA. The rabbit antisera proved to be idiotype specific, indicating that both MAs recognize separate epitopes. We except that anti-id Abs will prove to be of value for the differentiation of panels of LPS specific MAs.