The functional association of Lyt antigens with lymphokine production.

The effects of anti-Lyt antibodies on secretion of lymphotoxin, macrophage-activating factor and interferon were studied. Anti-Lyt-1 antibodies added to primary mixed lymphocyte reactions (MLR) significantly enhanced lymphokine secretion, whereas anti-Lyt-2 antibodies had no effect in primary responses. However, when added to secondary MLR, anti-Lyt-1 antibodies manifested moderate enhancing effect on lymphokine levels, whereas anti-Lyt-2 antibodies markedly reduced lymphokine secretion. These results suggested that T cells of different subsets produced lymphokines during primary and secondary responses. The Lyt phenotype of T cells involved in lymphokine secretion and the effects of anti-Lyt antibodies on selected T-cell subsets were therefore studied. It was demonstrated that the majority of lymphokine producing cells during primary MLR reside within the Lyt-1+2- population, which was potentiated by anti-Lyt-1 antibodies, but unaffected by anti-Lyt-2 antibodies. However, during secondary MLR, a considerable proportion of lymphokines was produced by the Lyt-1-2+ population, which was blocked by anti-Lyt-2 antibodies. Lymphokine production induced by concanavalin A, in contrast to that induced by alloantigens, was unaffected by anti-Lyt-2 antibodies. The implication of these results on the role of Lyt molecules in T-cell functions is discussed.