Functional characterization of human alloreactive T cell clones.

We have investigated the functional activity of alloreactive T cell clones, generated by limiting dilutions of MLC blasts. Clones displaying helper, suppressor, or cytotoxic functions (against Class I or Class II HLA antigens) were identified, using proliferative, 51Cr-release, and hemolytique-plaque induction assays. To determine whether functionally distinct clones share determinants that trigger the AMLC reaction we have tested the capacity of selected clones to cross-stimulate each other in secondary AMLC. Our data suggest that AMLC stimulatory determinants are related to common structure antigens of the T cell receptor for alloantigen, since helper clones, for example, (TLC #19) can induce memory responses to suppressor (TLC #209) as well as cytotoxic (TLC #207) clones and vice versa. The AMLC system seems well suited for studying network regulations within the T cell compartment.