Autocrine growth of CD4+ T cells. Differential effects of IL-1 on helper and inflammatory T cells.

The growth factor requirements of cloned lines representing two major subsets of CD4+ T cells were examined. The helper subset, which produces IL-4 as its autocrine growth factor, proliferates in response to IL-2 or to IL-4 in the presence of IL-1. The inflammatory subset, which produces IL-2 as its autocrine growth factor, proliferates in response to IL-2 and, in the presence of limiting amounts of IL-2, shows increased proliferation in the presence of IL-4. The inflammatory subset does not proliferate in response to IL-1 plus IL-4. This ability to respond to the combination of IL-1 plus IL-4 correlates with the presence of IL-1R on the cloned lines tested. These data suggest that IL-1 may play a controlling role in the clonal expansion of CD4+ T cells of different functional types. This, in turn, suggests means by which the immune response could be directed into humoral or cell-mediated responses.