Immunopathogenesis of experimental melanin-protein induced uveitis

The etiology of uveitis, a general term for inflammatory disorders of the uveal tract, has not been clarified. The purpose of this study is to investigate the immunopathogenesis during experimental uveitis induced by bovine melanin associated antigen (BMAA). Experimental melanin-induced uveitis (EMIU) was induced in male Lewis rats by injection of BMAA and delayed type hypersensitivity (DTH) testing was performed. Fluorescence-activated cell sorting (FACS) analysis was used to examine expression of cell adhesion molecules with antibodies to ICAM-1 and LFA-1. BMMA-induced uveitis resembled human AAU, with onset and peak at approximately 14 and 21 days after immunization, respectively. Signs of uveitis disappeared by 4 weeks postimmunization. Histologic study revealed major infiltration of the iris and ciliary body by numerous inflammatory cells and minor infiltration of the choroid. DTH testing showed that ears injected with antigen were more swollen than non-injected ears. FACS analysis demonstrated that ICAM-1 and LFA-1 expression increased during EMIU, with ICAM-1 expression higher than that of LFA-1. In conclusion, BMAA is uveitogenically active in Lewis rats. Immunopathogenesis appeared to be mediated by cell expressing ICAM-1 and LFA-1.