| Abstract: | To study T cell idiotype expression at the functional level, we developed a hapten-specific delayed-type hypersensitivity (DTH) system by which we avoid the complication of anti-hapten antibody and which is specific only for the immunizing hapten, and not for conjugate specific determinants. Immunization with ABA-Tyr and challenge with ABA diazonium induced footpad swelling with the characteristics of DTH. Anti-ABA antibodies did not contribute to this reaction, as they were undetectable in mice immunized with ABA-Tyr. Furthermore, this ABA-Tyr-specific DTH was under Ir gene control identical to that reported for ABA-Tyr-specific lymphocyte proliferation. All mouse strains tested responded to ABA-Tyr except those of the b haplotype across the entire Ia region. In contrast, contact sensitivity induced by ABA diazonium was not under apparent Ir gene control, probably reflecting 1) different specificities of the induced T cells and 2) the production of anti-ABA antibodies that contribute to the footpad swelling via an Arthus reaction. Having shown that ABA-Tyr can induce T cells mediating DTH, we then examined ABA-Tyr-reactive T cell clones, propagated in vitro, for their ability to mediate DTH. Such clones elicited a response identical to that seen with in vivo immunization with respect to dose dependency, I-Ak restriction, and antigen specificity. |
