Immunopathology Section

Experimental melanin protein-induced uveitis (EMIU)

EMIU is a T-cell mediated, bilateral, recurrent uveitis. EMIU is induced in the rat and the monkey by immunization with purified bovine ocular melanin protein. In EMIU, delayed-type hypersensitivity, lymphocyte proliferation, and agglutination to bovine ocular melanin and melanin-associated protein are positive. MHC class II antigens and adhesion molecules are expressed on ocular resident cells before ocular infiltration of T cells and macrophages. Unlike experimental autoimmune uveoretinitis (EAU) in the rat, anterior uveitis (iridocyclitis) is an important pathological feature and retinal involvement is observed only in some severe and/or recurrent cases of EMIU. Unlike endotoxin-induced uveitis (EIU) in the rat and mouse, a spontaneous recurrence occurs in about 1/4 cases of EMIU and recurrence can be easily induced with minimal dosages (5 micrograms) of lipopolysaccharide (LPS). The relapsing feature makes EMIU a practical model for the evaluation of therapies initiated during established disease and aimed at the prevention of recurrence. Thus, it more closely resembles certain forms of uveitis in humans.

Many inflammatory cells infiltrate the iris (I), ciliary body (CB) and choroid (Ch). The cornea (Co) and retina (R) are free of disease.