Mouse monoclonal anti-idiotypic antibodies to HIV p24: immunochemical properties and internal imagery.

Two mouse monoclonal antibodies (VIC5 and VIC6; referred to as Ab1) reacting with the p24 core antigen of HIV-1 were used to produce mouse monoclonal anti-idiotypic antibodies (Ab2). Six anti-idiotypic antibodies were characterized. The five anti-idiotypic antibodies directed against VIC6 partly competed which each other and thus defined a set of overlapping idiotypes on Ab1. All 6 Ab2s inhibited the binding of the corresponding anti-p24 antibody to antigen, although four (W1, Y16, Y6, X14) were markedly more inhibitory than the remaining two (G6, Y11). All six Ab2s were antigen-inhibitable; however the interaction of G6 and Y11 with Ab1 was blocked with considerably less soluble p24 antigen than the remaining four. Correspondingly, G6 and Y11 had lower affinities for Ab1 than did W1, Y6 and X14; the affinity index of Y16 was equivalent to that of Y11. None of the Ab2s reacted with H or L chains of Ab1 after reduction on SDS-gels. Similarly, both Ab1s failed to react with the H or L chains of Ab2. These criteria appeared to define at least four of these Ab2s as internal image antibodies whose image is composed of both H and L chains. The anti-idiotypic antibodies were injected either individually or as a combined preparation of all 6 into syngeneic mice and Porton rats. Despite the presence of anti-anti-idiotypic antibodies (Ab3) in these animals, when used individually no antigen-specific antibodies were found. A small response to p24 antigen was induced in 3 of 6 mice using preparations containing all 6 anti-idiotypes.