Myelin basic proteins induce anterior uveitis in Lewis rats

Purpose. To study the role of myelin basic proteins (MBP) in the induction of anterior uveitis in Lewis rats as a model for uveitis associated with multiple sclerosis (MS). Methods. Experimental autoimmune encephalomyelitis (EAE) was induced in Lewis rats by injection of MBP emulsified in complete Freund's adjuvant (CFA), or passively by injection of MBP-specific T cells. The animals were examined for signs of EAE. Eyes were removed at various times post-immunization, processed for routine histology, and examined for signs of inflammation. Phenotyping of cells obtained from the anterior segment was performed using flow cytometry. Results. Anterior uveitis could be induced by injection of MPB, its encephalitogenic peptide 87-99, or passively transferred to naïve rats with MBP-specific T cell line. The onset of AU coincided with limb paralysis, but uveitis persisted after clinical signs of EAE subsided. Upon histopathological examination, cells lining the anterior surface of iris, multiple iris nodules and perivascular lesions were frequently observed. Cells in the trabecular meshwork, in the ciliary body, and in the aqueous humor were present. Flow cytometry analysis of T cells specific for the MBP that were contained within the anterior segment during inflammation revealed the presence of cells exclusively expressing Vβ8.2 T cell receptor and OX-40 CD4-activation protein. Conclusions. Our data suggest that MPB are encephalitogenic and uveitogenic in Lewis rats, and that the Vβ8.2 positive T cells in the eye represent encephalitogenic T cells. Many of those T cells were distributed in the iris and the anterior chamber. These findings indicate that these MBP-specific T cells may play a critical role in EAE as well as in AU.