Purpose: To study the immunopathology of experimental melanin-protein-induced uveitis in the Lewis rat.
Methods: Rats were immunized with bovine ocular melanin protein. The kinetics of experimental melanin-protein-induced uveitis was studied by clinical examination and immunopathology. Cellular and humoral responses were evaluated by lymphocyte proliferation, delayed-type hypersensitivity, and agglutination. After clinical disease subsided, recurrent experimental uveitis was induced with a low-dose footpad injection of lipopolysaccharide.
Results: Experimental melanin-protein-induced uveitis was characterized by bilateral uveal infiltration mainly with lymphocytes and monocytes. Delayed-type hypersensitivity, lymphocyte proliferation, and agglutination to bovine ocular melanin protein were positive. Expressions of major histocompatibility complex class II and intercellular adhesion molecule-1 were observed before ocular infiltration. The predominantly infiltrating cells were CD4+ lymphocytes. Experimental melanin-protein-induced uveitis subsided within 1 month, spontaneously recurred within 1 week in approximately one quarter of the rats, and was inducible in most rats with 5 micrograms of lipopolysaccharide confirmed by histopathology.
Conclusions: Experimental melanin-protein-induced uveitis is a T-cell-mediated autoimmune uveitis, resembling noninfectious recurrent iridocyclitis and choroiditis in humans.