The exact pathogenic mechanisms involved in autoimmune and inflammatory eye diseases are not known. However, studies during the past few years indicate that a T cell infiltrate, T cell sensitization to retinal antigens and expression of major histocompatibility complex (MHC) class II antigens are associated with this process. In this report we show that the lymphokines, IL-2 and IFN-gamma, are present in the human eye during inflammatory and autoimmune diseases. The presence of these lymphokines is associated with a lymphocyte infiltrate, predominantly of T cell origin, and with the expression of MHC class II antigens on both the infiltrating cells and ocular resident cells, that is, retinal pigment epithelial (rpe) cells and retinal vascular endothelial cells. Furthermore, in vitro studies demonstrate that IFN-gamma can enhance the expression of the HLA-DR determinant on both of these cell types. These observations suggest that lymphokine induced class II antigen expression may serve as a local amplification system in autoimmune and inflammatory eye diseases. A better understanding of the role of lymphokines in the mechanisms involved in the development of autoimmunity and inflammation may be beneficial in the treatment of these diseases.