Experimental autoimmune anterior uveitis. The preparation of uveitogenic ocular melanin.

PURPOSE: The purpose of this study was to develop a rapid procedure for the preparation of melanin with a specific, highly uveitogenic activity.

METHODS

A crude melanosome fraction was isolated from bovine choroids (containing remnants of adhering retinal pigment epithelium). The fraction was extracted with hot 2% sodium dodecyl sulfate, and Lewis rats were immunized with the purified melanin, using pertussis toxin as coadjuvant.

RESULTS

The purified melanin was free from pathogenic photoreceptor antigens and other accompanying or adsorbed proteins. It was able to evoke severe, acute, anterior uveitis with the typical characteristics of experimental autoimmune anterior uveitis (EAAU; without retinitis or pinealitis), even at the level of 1 micrograms melanin protein.

CONCLUSIONS

The rapidly prepared ocular melanin exhibits the same qualities as purified choroidal or retinal pigment melanins obtained by much more laborious procedures (which also deliver other subcellular fractions for investigation). It is suitable for the study of the immunopathogenesis of EAAU, which is a new model for human acute anterior uveitis.