EXPERIMENTAL MELANIN-PROTEIN-INDUCED UVEITIS IN THE LEWIS RAT - IMMUNOPATHOLOGIC PROCESSES

Purpose: To study the immunopathology of experimental melanin-protein- induced uveitis in the Lewis rat. Methods: Rats were immunized with bo vine ocular melanin protein. The kinetics of experimental melanin-prot ein-induced uveitis was studied by clinical examination and immunopath ology. Cellular and humoral responses were evaluated by lymphocyte pro liferation, delayed-type hypersensitivity, and agglutination. After cl inical disease subsided, recurrent experimental uveitis was induced wi th a low-dose footpad injection of lipopolysaccharide. Results: Experi mental melanin-protein-induced uveitis was characterized by bilateral uveal infiltration mainly with lymphocytes and monocytes. Delayed-type hypersensitivity, lymphocyte proliferation, and agglutination to bovi ne ocular melanin protein were positive. Expressions of major histocom patibility complex class IL and intercellular adhesion molecule-1 were observed before ocular infiltration. The predominantly infiltrating c ells were CD4+ lymphocytes. Experimental melanin-protein-induced uveit is subsided within 1 month, spontaneously recurred within 1 week in ap proximately one quarter of the rats, and was inducible in most rats wi th 5 mu g of lipopolysaccharide confirmed by histopathology. Conclusio ns: Experimental melanin-protein-induced uveitis is a T-cell-mediated autoimmune uveitis, resembling noninfectious recurrent iridocyclitis a nd choroiditis in humans.