Immune response to phosphorylcholine. IX. Characterization of hybridoma anti-TEPC15 antibodies.

Hybridoma antibodies against the PC-binding T15 BALB/c myeloma protein were raised by cell fusion with anti-T15 A/He immune cells. The idiotype specificity of these monoclonal anti-T15 antibodies was determined with a panel of different myeloma and hybridoma immunoglobulins. Two types of anti-T15 antibodies are seen. One reacts with a number of different IgA myeloma proteins and with serum IgA of certain strains of mice; this reactivity most likely is due to allotypy. The other group consists of anti-T15 antibodies that are specific for the T15 idiotype and are therefore termed anti-idiotypic. The bindings of the anti-idiotype antibodies to T15 were specifically inhibited by T15 (F(ab')2 but not by other PC-binding myeloma proteins of different idiotypes. The relationship of the idiotype-specific anti-T15 antibodies to the PC-binding site of the T15 idiotype was analyzed by hapten inhibition of anti-idiotypic binding and by inhibition of BALB/c anti-PC splenic hemolytic plaque formation. Anti-T15 antibodies, for which the T15 binding is inhibited by PC or PC-BSA, also specifically inhibit anti-PC plaque formation. These antibodies are labeled site and near-site anti-idiotypic antibodies. Site and near-site-specific anti-idiotypic antibodies recognize different idiotopes on the T15 molecules. The possible differential biologic activities of these anti-idiotopes in idiotype network regulation is considered.