Relationship between T cell subpopulations and the mitogen responsiveness and suppressor cell function of peripheral blood mononuclear cells in normal individuals.

A simultaneous analysis was made of numbers and proportions of T cell subsets (T mu and T gamma cells), lymphocyte responsiveness to non-specific mitogens in vitro and 'short-lived suppressor cell activity' in peripheral blood mononuclear cells (PBMC) of normal individuals. No correlation was found between either T gamma or T mu cells and the 'short-lived suppressor cell activity', suggesting that suppression in this system is not a reflection of quantitative alteration in these subsets. However, a highly significant positive correlation was found between numbers of T mu cells and PBMC responses to the mitogens phytohaemagglutinin, concanavalin A and pokeweek mitogen. This may reflect either a helper effect of T mu cells on lymphocyte proliferation in response to mitogens or the presence of the majority of mitogen-responsive cells within this subpopulation. As in normal individuals lymphocyte responsiveness correlates with the number of circulating T mu cells, it is possible that a reduction in these cells in disease states may contribute to defects in cell-mediated immunity.