Cytokines are communication signals between leukocytes and organ resident cells. Interleukin 1 (IL-1) a pleiotropic cytokine produced by many cell types, most notably macrophages, can stimulate a general inflammatory reaction by causing the activation of a variety of cells which then, among their other functions, release a cascade of other cytokines. One of them is Interleukin 8 (IL-8), which has more direct action of activating the neutrophils and T lymphocytes. Intravitreal injection of IL-8 was compared to that of IL-1 in both Lewis and Fischer rats. IL-8 induced milder inflammation than IL-1. Lewis rats show a higher inflammatory response to the injections than do Fischer rats. These data suggest that IL-8 may be active as one component in neutrophil-mediated ocular disease. Further understanding of the role of each cytokine in ocular inflammation, will require study of the production of endogenous cytokines in the eye. Ocular antigens play an important role in autoimmune diseases. S-antigen (S-Ag), a retinal soluble antigen, can induce experimental autoimmune uveoretinitis. In situ, study of S-Ag expression in human fetal eyes demonstrated an embryonic development pattern similar to that of other mammals. The expression of S-Ag in RNA of non-retinal fetal tissues may suggest its involvement in certain ocular diseases. Lens crystallin proteins alpha, beta and gamma were also found in human fetal iris and retinoblastoma cells. The roles of their expression in non-lenticular tissue require further investigation.
