Lymphokine-independent induction of macrophage membrane IL-1 by autoreactive T cells recognizing either class I or class II MHC determinants

Here we report that autoreactive T cell clones and T cell hybridomas that recognize class I or class II MHC determinants can induce IL-1 expression on cultured macrophages in an MHC-restricted manner. This genetic restriction of membrane IL-1 (mIL-1) induction is not absolute, however; it is manifest only in macrophages that have been cultured for several days before stimulation. Macrophages that are evaluated within 24 h after adherence display a basal level of mIL-1, and the T cell-induced augmentation of basal mIL-1 expression is not MHC-restricted. It appears that T cells of both Th1 and Th2 type have the capacity to induce mIL-1, suggesting that this function is not limited to the T cell subset (Th2) that is able to use IL-1. Most importantly, the ability of T cells to induce IL-1 on macrophages seems to occur by virtue of direct cellular interactions, and is independent of lymphokine secretion. The induction event is rapid enough (2 to 4 h) to allow T cells to interact with both antigen and IL-1 during the initial T cell/macrophage contact. These findings thus reveal an efficient mechanism for the induction of IL-1 during Ag presentation to T cells.