REGULATORY INTERACTIONS BETWEEN L-GLUTAMIC ACID(60)-L-ALANINE(30)-L-TYROSINE(10)(GAT)-SPECIFIC SUPPRESSOR FACTORS AND MURINE T CELL SUBPOPULATIONS (HELPER, CLONES)

Different classes of antigen-specific suppressor T cells, their cellular extracts, or monoclonal products are capable of mediating suppression of the in vitro splenic antigen-specific plaque forming cell (PFC) response. However, neither the functional relationship of the different classes nor the cellular target of the effector-suppressor cell are unambiguously defined. These questions have been addressed using monoclonal suppressor factors specific for L-glutamic acid('60)-L-alanine('30)-L-tyrosine('10) (GAT) and cloned GAT-specific helper T cells to reconstitute the GAT-specific PFC response of unprimed splenic B cells and macrophages.; Our results demonstrate that GAT-TsF2 acts by suppressing the GAT-specific helper T cell population. First, the H-2 restricted, monoclonal GAT-TsF2 suppresses the PFC response in cultures in which the only cell identical with the factor at the H-2 locus is the helper T cell clone. Second, the plaque forming cell response is suppressed by pre-incubating the helper T cell clone with GAT-TsF2 and GAT prior to adding the clones to culture. Finally, the clone is able to adsorb GAT-TsF2 when the incubation is performed on ice in the presence of GAT.; The specificity of the interaction between the helper T cell and GAT-TsF2 was examined. Adsorption of the factor by the cell requires antigen, H-2 syngenicity between the factor and cell, a common antigen-specificity, and recognition of the class of the suppressor factor. The specificity and strong correlation between adsorption and function suggest the presence of a receptor on the helper T cell for TsF2. The identification of several monoclonal antibodies that interfere with the adsorption of the factor corroborate this conclusion and should facilitate the biochemical extension of this study.; Finally, by limiting the heterogeneity of the responding cell populations and the suppressor cell component, we have demonstrated the requirement of an Lyt 2('+) T cell for suppression by the unrestricted GAT-TsF1 factor.