Class II antigens on retinal vascular endothelium, pericytes, macrophages, and lymphocytes of the rat

Class II histocompatibility complex antigens on the retinal vascular endothelium may allow these cells to function as antigen-presenting cells to circulating T cells. The present study investigated induction of class II antigens in vitro to characterize the response under controlled conditions. Retinal vascular endothelium from Lewis and Brown Norway rats (high versus low responders in experimental autoimmune uveitis) were exposed in vitro to recombinant rat gamma interferon, interleukin-1, interleukin-2, or Concanavalin-A spleen supernatant. Retinal pericytes, macrophages and lymphocytes were studied in comparison. A newly adapted ELISA technique was used to assay levels of antigen expression. Class II antigens (I-A OX6, I-E OX17, polymorphic I-A OX3), class I antigens (OX18), macrophage marker (OX42), macrophage and T helper cell marker (W3/25), and T suppressor/cytotoxic cell marker (OX8) were studied. Results showed that retinal vascular endothelium normally expresses very little class II antigen. However, high levels of I-A and I-E were induced by interferon or spleen supernatant. The levels of class II antigen approached that of the traditional antigen-presenting cell (macrophage) and were much higher than levels for pericytes and lymphocytes. The same doses of interferon showed larger increases in the Lewis rat compared to Brown Norway. No effect was seen with interleukin-1 or -2. Therefore, retinal vascular endothelium may be induced by gamma interferon to express class II antigens with degree of induction greater than or equal to the macrophage, and higher levels of induction were seen in the high responder strain.(ABSTRACT TRUNCATED AT 250 WORDS)