Anti-Ia antibodies inhibit the spontaneous secretion of IL-1 from silicotic rat alveolar macrophages.

Class II antigens of the major histocompatibility complex (Ia) are important components in the investigation of cell-mediated immune responses. Several reports have indicated that anti-Ia monoclonal antibodies suppress disease development in animal models. In this paper, the expression of Ia and the effect of anti-Ia on IL-1 secretion from alveolar macrophages (AM) from silica-treated rats was examined. The results obtained showed that 45% of silicotic AM, but only 5% of AM from normal control rats, express Ia antigen. Anti-Ia treatment of silicotic AM reduced IL-1 secretion by 55%. We conclude that anti-Ia immune suppression may involve the inhibition of IL-1 secretion.