Guinea pig T-cell in vitro proliferative responses to tyrosine-azobenzenearsonate-pulsed and azobenzenearsonate-coupled macrophages have different specificities

The cell interactions involved in azobenzenearsonate-N-acetyl-tyrosine (ABA-tyr)-induced delayed hypersensitivity in the guinea pig were studied by in vitro blastogenesis. The ABA-sensitive lymphocyte was demonstrated to be a T lymphocyte and its presence in peritoneal exudate cells was shown to be much higher than spleen or lymph node populations. The secondary response of ABA-sensitized lymphocytes to ABA-tyr in culture is dependent on the presence of an accessory cell, with both splenic and peritoneal macrophages being equally effective. ABA coupled directly to macrophages as an immunogen induced strong responses to itself and not to ABA-tyr-pulsed macrophages or ABA-tyr in solution. The reverse was true in animals, immunized with ABA-tyr. ABA conjugated to thymocytes, L₂C leukemia cells, and guinea pig erythrocytes however, did not elicit significant responses. The results obtained in animals immunized with ABA- or ABA-tyr-modified cells was similar whether or not CFA was used. The difference in specificity shown between ABA-coupled and ABA-tyr-pulsed macrophages favors a single receptor hypothesis for T-cell recognition.