Expression of ocular autoantigens in the mouse thymus.

PURPOSE. The occurrence of eye diseases of autoimmune nature, as well as experimental models of these diseases, has been attributed to the sequestration of ocular antigens from the immune system, that prevents the development of tolerance against these antigens. Here, we tested this assertion by examining whether transcripts of certain ocular antigens are constitutively expressed in the thymus, the site of central tolerance induction. RNA was isolated from the eyes and thymi of two mouse strains and analyzed for the expression of genes encoding four retinal and three lens proteins by reverse transcribed-polymerase chain reaction. Southern blot and DNA sequence analyses. We detected gene transcripts of S-Antigen (S-Ag), interphotoreceptor retinoid-binding protein, opsin, recoverin, lens major intrinsic protein (MIP), alphaA-, alphaA(-ins)- and gamma-crystallins in the thymi of BALB/c and FVB/N mouse strains. DNA sequence analysis of the thymic MIP and S-Ag transcripts confirmed their identity to the lens and retinal proteins, respectively. Our results reveal that transcripts of several ocular-specific proteins are expressed in the thymus and suggest that the commonly held view that ocular-specific antigens are sequestered from the immune system should be modified.