Experimental ocular hypersensitivity. Histopathologic changes observed in rabbits receiving a single injection of antigen into the vitreous

1. 1. Histopathologic observations have been made on rabbit eyes given single intravitreal injections of crystalline egg albumin. One series received 1.0 mg. ("large-dose") which produced a clinically apparent uveitis in all injected eyes after a latent period of six to eight days. The other series received 0.05 or 0.10 mg. ("small-dose") which, with one exception, failed to provoke a clinically significant inflammatory reaction. 2. 2. In both the large and small dose series, the intraocular reaction was principally mononuclear, but in the eyes given the small dose there was virtually no uveal reaction while those given the large dose exhibited pronounced iridocyclitis and chorioretinitis. 3. 3. Although in most cases the inflammatory reaction was entirely nongranulomatous, a few eyes at the height of reactivity exhibited granulomatous lesions. 4. 4. Complications were not observed in the small-dose series but in some of the eyes injected with the large dose the following were noted: retinal detachment, degeneration of visual cells, preretinal membraneformation, fixed folds of retina, degeneration of vitreous, and gliosis of retina and optic disc. 5. 5. The spontaneous inflammatory response observed in these eyes has been compared to the "progressive immunity reaction" described by Gell and Hinde.^6,7 These lesions have been discussed in terms of the fundamental immunological mechanisms which might contribute to their pathogenesis.