Cross-reactive idiotypic determinants on murine anti-(T,G)-A-L antibodies

Anti-idiotypic sera specific to anti-(T,G)-A-L antibodies of high responder C3H.SW (H-2 ^b, Ig-1 ^a) mice were prepared in guinea pigs. The anti-idiotypic sera bind specifically 30% of the iodinated antibodies of C3H.SW against (T,G)-A-L and inhibit antigen binding of these antibodies. These anti-idiotypic sera do not react with anti-(T,G)-A-L antibodies produced in the congenic strain, CWB (H-2 ^b, Ig-1 ^b), which differ from the C3H-SW strain by allotype, but cross-react with anti-(T,G)-A-L produced in BALB.B10 (H-2 ^b, Ig-1 ^a), which differ from C3H.SW in its genetic background but possess the same allotype. These results suggest a linkage between the idiotypic determinants analyzed and Ig-1 ^a allotype. Immunization of C3H.SW mice with the ordered peptide antigen (T-T-G-G-)-A-L led to the production of antibodies that share idiotypic determinants with C3H.SW anti-(T,G)-A-L antibodies, confirming previous conclusions that Tyr-Tyr-Glu-GLu is the major determinant of the random (T,G)-A-L. Anti-(T,G)-A-L antibodies produced in low responders C3H/DiSn (H-2(k), Ig-1 ^a) by immunization with (T,G)-A-L complexed with methylated bovine serum albumin (MBSA) cross-react with the anti-idiotypes prepared against the high responder anti-(T,G)-A-L antibodies. The low responder antibodies were approximately 3- to 5-fold less efficient in inhibiting the idiotypes-anti-idiotypes reaction. However, anti-(T,G)-A-L produced in high responders by immunization with (T,G)-A-L + MBSA were identical to the low responder antibodies in their idiotypic content as judged by inhibition of the binding of the idiotypes to the anti-idiotypes. These results demonstrate that high and low responders that possess Ig-1 ^a allotype have a similar repertoire of B cells producing anti-(T,G)-A-L antibodies.