[Analysis of in vitro immune responses in humans using T cell clones and monoclonal antibodies]

In this study, in vitro immune responses to PPD were analysed using T cell clones and monoclonal antibodies against DR and MB antigens. Effects of monoclonal antibodies on proliferative responses of PBM (peripheral blood mononuclear cell) to PPD (primary response) and on those of PPD-primed PBM to PPD (secondary response) were tested. The results showed that anti-DR monoclonal antibodies, HU-4 and HU-20, inhibited PPD specific PBM proliferative responses through inhibition of antigen presentation with steric hindrance to DR antigens of APC (antigen presenting cell). In contrast, an anti-MB 3 monoclonal antibody, HU-18, did not affect any of the responses tested. Furthermore, three PPD specific T cell clones established were restricted by DR molecules, but not by MB molecules. Thus, it was concluded that DR antigens played an important role in the immune responses to PPD. This result is different from the findings in mice where I-A antigens serve as restriction molecules in PPD specific responses. This difference in restriction molecules between species was discussed.