Monoclonal Ligand Binding Site Related Anti-Idiotypic Antibodies Elicited with a Polyclonal Kinin Antibody

Abstract

Splenocytes from mice immunized with homogenous, polyclonal, rabbit kinin antibody (BK21) were fused using polyethylene glycol with the mouse myeloma cell line SP2/o. Eleven monoclonal antibodies, whose binding to BK21 could be inhibited by bradykinin, were obtained from 3 fusions. All of these anti-idiotypic antibodies were of the IgG_lk isotype, except for one, which was an IgG_2ak. An IgM_k, auto-anti-idiotypic antibody, reactive with BK21 was obtained from a fusion of SP2/o cells and splenocytes from a mouse immunized with bradykinin conjugated with carbodiimide to keyhole limpet hemocyanin. Bradykinin could completely inhibit the binding of all of the anti-idiotypic antibodies to BK21 in an enzyme-linked immunosorbent assay. This result is consistent with the anti-idiotypic antibodies being reactive with the ligand binding sites of BK21. It was possible to separate the anti-idiotypic antibodies into 2 groups. The first group, 10 of the 12 antibodies tested, was more sensitive to inhibition by bradykinin than the second group and was not readily inhibited by des-Arg⁹-bradykinin. The second group was about 7 times more sensitive to inhibition by des-Arg⁹-bradykinin than by bradykinin. Further experiments will be needed to determine whether or not these monoclonal anti-idiotypic antibodies are "internal image" antibodies.