Experimental allergic uveitis: clinicopathologic features associated with varying doses of S antigen

Considerable differences were observed in the experimental autoimmune disease elicited by retinal S antigen, depending on the immunizing dose. An inoculum of 50 microgram produced a massive panophthalmitis containing many polymorphonuclear leukocytes, eosinophils, and mononuclear cells. A less severe endophthalmitis was seen in animals receiving 25 microgram of antigen. Animals receiving between 5 and 10 microgram of antigen developed a disease characterized by a granulomatous uveitis. The inflammatory infiltrate consisted primarily of mononuclear and epithelioid elements and appeared virtually identical to that seen in sympathetic ophthalmia. One microgram of S antigen produced primarily a nongranulomatous posterior uveitis composed chiefly of mononuclear cells. The principal change in the character of the disease occurred at dose levels between 10 and 25 microgram. This change consisted of the disappearance of polymorphonuclear leukocytes and eosinophils at the lower dose levels. These histopathologic changes suggest that at higher dose levels an immune complex disease may be superimposed on or replace a presumably cell-mediated hypersensitivity response.