CD11 molecule defines two types of suppressor cells within the T8⁺ population

It has been shown that T8⁺ cells are comprised of functionally heterogeneous subpopulations such as suppressor, cytotoxic, and NK cells. In this report, we attempted to delineate the functional heterogeneity of T8 cells defined by anti-CD11 antibody (anti-Mol). Although allospecific cytotoxic activity was restricted to the T8⁺Mol^- subset, suppression of PWM IgG synthesis could be elicited in both the T8⁺Mol⁺ and the T8⁺Mol^- subset of cells. However, the mechanism of suppression was different in these two subsets. Suppression by the T8⁺Mol^- subset of cells required the interaction with the T4⁺2H4⁺ suppressor inducer cells, whereas the T8⁺Mol⁺ subset of cells could suppress in the absence of the suppressor inducer cells. Moreover, recombinant interleukin-2 alone could augment this suppression by the T8⁺Mol⁺ subset, but did not induce suppression by the T8⁺Mol^- subset. In contrast, NK and LAK activity was exclusively found in the T8⁺Mol⁺ subset of cells but not in the T8⁺Mol^- subset of cells. These results suggest that the CD11 molecule is useful for distinguishing novel subsets of T8 cells.