Monoclonal antibodies raised against the idiotype of the murine B cell lymphoma, BCL1 act primarily with heavy chain determinants.

Anti-idiotypic antibodies can be used as probes to distinguish neoplastic cells from their normal counterparts. In addition they have been used in the passive therapy of B cell tumors. In this report we describe a panel of 7 rat monoclonal antibodies raised against idiotypic determinants carried by the IgM molecule of the BCL1 lymphoma. The majority (6/7) of these antibodies recognize private idiotypic determinants that are carried on the isolated mu heavy chain of the molecule, and do not require the lambda chain for reactivity. This is unusual for antibodies raised against the idiotype of the whole immunoglobulin molecule, which normally require both chains for reactivity. The antibodies do not, however, bind peptides corresponding to the complementarity determining regions of the mu heavy chain of BCL1. The antibodies perform well in complement mediated cytotoxicity, and, in at least one case, are effective in the passive immunotherapy of BCL1 lymphoma.