Abstract Interferon-γ (IFN-γ) is a potent lymphokine which can modify a variety of cellular processes. One of the mechanisms involved in these processes is the ability of IFN-γ to alter the regulation and expression of cellular proteins. Using analytical flow cytometry, we show that recombinant human IFN-γ can enhance the expression or retinal S-antigen in retinoblastoma cells. This enhancement was selective since two other retinal cell proteins, interphotoreceptor binding protein (IRBP) and photo-6, were not affected by IFN-γ treatment. Retinal S-antigen plays an important role in vision and is one of the retinal proteins capable of inducing an inflammatory eye disease called experimental autoimmune uveitis. These studies therefore demonstrate an important role for this lymphokine, that is, the enhanced expression of a neuronal cell protein. This finding may also identify additional mechanisms by which IFN-γ may participate in immunopathologic events in nervous tissue.