AbstractThe MOPC460 idiotype is expressed in mice with the IghCaallotypic haplotype after anti‐2,4‐dinitrophenyl (DNP) immunization. We have previously shown that two monoclonal syngeneic anti‐idiotypic antibodies (IDM 92‐13 and IDM 41‐27) define two distinct idiotopes (the 460.92 and the 460.41) on the M460 idiotype. The current study demonstrates that only one idiotope (460.92) is recurrently expressed after antigen immunization in IghCapositive mice and also that, immunization against the monoclonal anti‐idiotypic molecules induces the synthesis of 460.92 idiotope positive anti‐DNP antibodies. However, the detection of such molecules is only possible when animals with the IghCaallotypic haplotype are immunized with the IDM 92‐13 molecules. Immunization of mice with either of the two monoclonal anti‐idiotypic antibodies never results in the synthesis 460.41 positive molecules. Therefore, whatever protocol of immunization used, the expression of 460.92 was all