Dissection of immunoregulatory subpopulations of T lymphocytes within the helper and suppressor sublineages in man

The helper/inducer (Leu-3) and suppressor/cytotoxic (Leu-2) sublineages of human peripheral blood T cells can both be subdivided into functionally distinct subsets with anti-Leu-8, a new monoclonal antibody that identifies 75 ± 10% of the Leu-3 cells and 60 ± 10% of the Leu-2 cells. Using the autologous MLR as a T cell-dependent stimulus for immunoglobulin synthesis, we have shown that the major helper effect for antibody formation lies within the numerically minor Leu-3,8^- subset. In addtion, neither Leu-2,8⁺ nor Leu-2,8^- cells alone suppress Leu-3-induced immunoglobulin synthesis, but in combination these subsets are markedly inhibitory. These results indicate that at least two phenotypically distinct cell types or suppressor lineage interact to produce suppression of an immune response in man.