Studies of idiotypic antibodies: reactions of isologous and autologous anti-idiotypic antibodies with the same antibody preparations.

Outbred rabbits were immunized with keyhole limpet hemocyanin diazotized to p-aminophenyl-N-trimethylammonium chloride (TMA). Anti-TMA antibodies were specifically purified and the F(ab')2 fragments were isolated after pepsin digestion. Glutaraldehyde-polymerized anti-TMA F(ab')2 fragments were reinjected back into the same animal that synthesized the antibodies to elicit an autologous anti-idiotypic (AAI) antiserum and were also injected into an allotypically matched recipient to elicit isologous anti-idiotypic (IAI) antiserum. AAI and IAI antisera reactive with the same F(ab')2 preparation were compared by assaying the populations of anti-TMA molecules reactive with each antiserum. The assays showed that the AAI antiserum reacted with smaller populations of molecules than did the IAI antiserum. The population of molecules recognized by the AAI antiserum was contained within the larger population recognized by the IAI antiserum. Hapten inhibition studies showed that the differences in the populations of molecules recognized by each antiserum were not related to the hapten-binding properties of the idiotypic antibodies: in one case both AAI and IAI reactions were equally inhibited by hapten; in another, the AAI reaction was inhibited more than was the IAI; in another, the IAI reaction was inhibited more.