Expression of Ia antigen by ocular tissues of mice treated with interferon gamma.

Intraperitoneal injections of interferon gamma (IFN-gamma) induced or enhanced the expression of Ia antigen by selected murine ocular tissues. In contrast, topical application of this lymphokine had no effect. Ia antigen expression was noted in most cellular components of the conjunctiva, iris, ciliary body, choroid and sclera of treated mice. Intense staining was also found in stromal cells of the cornea, but no Ia reactivity was detected in the corneal epithelium. The lack of staining in the corneal epithelium is in contrast to the strong reactivity in the adjacent conjunctival epithelium, as well as in the skin epithelium. There was no increase in the number of Langerhans cells in the peripheral cornea and limbus, or in their intensity of staining with the anti Ia antibodies. The pattern of Ia expression in ocular tissues of mice treated with IFN-gamma is similar to that of rats with experimental autoimmune uveoretinitis (EAU) except that Ia is expressed more regularly and with higher intensity by the retinal vascular endothelium of rats with EAU than by that of IFN-gamma-treated mice. The findings in the current study thus support the notion that IFN-gamma may be involved in immune-mediated inflammation in the eye.