Functional heterogeneity among the T-derived lymphocytes of the mouse: III. Helper and suppressor T-cells activated by concanavalin A

We have studied the properties of T-cells which when activated by concanavalin A (Con A) either suppress or help the in vitro humoral response of mouse spleen cells. Previously established criteria for the T-cell populations, T₁ and T₂ were applied. T₁ cells were defined by their short half-life (2–3 wk) after adult thymectomy (ATx) and their resistance to small doses of antithymocyte serum (ATS). T₂ cells were defined by their long half-life (~15 wk) and their high sensitivity to ATS. T-cells which could be activated by Con A to help the response to the thymus-dependent antigen, sheep red blood cells, were found mainly in the T₂ subpopulation. T-cells which could be activated by Con A to suppress the response to the thymus-independent antigen, trinitrophenyl-lipopolysaccharide (TNP-LPS), were found within both the T₁ and T₂ subpopulations.These results, our previous results, and those of others suggest that the T-cell responses to phytomitogens distinguish precursors committed to different functions, while the T₁ and T₂ classifications distinguish T-cells at different stages of maturation.