Extensive cross-reactive idiotypy among guinea-pig anti-TMA antibodies.

The extensive cross-reactivity of the immune response by strain 13 (S-13) and outbred guinea-pigs (GP) to either the bivalent antigen L-tyrosine-p-azophenyltrimethylammonium (tyr(TMA)) [H-L-tyr(TMA)-NH-(CH2)3]2 (T-S-T) or the conjugate 3-(p-trimethylphenylazo)-N-acetyl-L-tyrosylglycylglycine-bovine serum albumin (T-S-B) was examined. Antibody (Ab) isolated from a single T-S-B immune S-13 animal by affinity chromatography (proband) was used to induce anti-sera (anti-Id) in a rabbit and a syngeneic S-13 GP. These anti-Ids were both shown to be idiotype specific by means of a tube binding radioimmunoassay (TBRIA). A series of S-13 anti-(T-S-B), S-13 anti-(T-S-T), and outbred anti-(T-S-B) antisera were tested as inhibitors in the TBRIA through a range of 6-200 ng of anti-TMA Ab equivalent. Each was found to inhibit extensively, indicating a considerable amount of cross-reactivity of idiotypes present in the sera. In general, the rabbit anti-Id recognized more cross-reactivity among the various antisera than did the GP reagent, particularly among those from T-S-B immune S-13 animals. Addition of free "hapten" tyr(TMA) as an inhibitor specifically displaced 55% of the label from the rabbit reagent at 10(-5)M, while only 25% of binding of the proband to GP anti-Id was inhibitable at this concentration. These findings suggest that the rabbit and GP anti-Ids are directed predominantly to different determinants, the rabbit recognizing the less variant, hapten-binding portion of the GP Ab more than does the syngeneic GP reagent. Data from isoelectric focus patterns support the impression of a highly restricted Ab response to TMA. While each serum gives a distinct binding pattern, several bands appear shared by all responders.