Interleukin-2 production and response by helper T-cell subsets in man.

This study investigated the production of, and response to, the lymphokine interleukin-2 (IL-2) by functional subsets of human CD4+ T lymphocytes. Fresh peripheral blood mononuclear cells (PBMC) were sorted into CD4+2H4+/4B4- suppressor-inducer cells, and CD4+2H4-/4B4+ helper cells. The suppressor-inducer subset proliferated well in response to the T-cell mitogens concanavalin A (Con) A and phytohaemagglutinin (PHA), and produced IL-2. The helper cells produced no detectable IL-2 and proliferated poorly. However, the latter population were induced to express functional IL-2 receptors by Con A or purified protein derivative (PPD), and proliferated well if supplied with exogenous rIL-2. These findings suggest that the two functional CD4 subsets are not independent, or counteracting, but rather that the generation of T-cell help is likely to involve cooperative interactions between the two subsets.