Phenotypes of T cells infiltrating the eyes in autoimmune anterior uveitis associated with EAE

Lewis rats immunized with myelin basic protein (MBP) develop experimental autoimmune encephalomyelitis (EAE) and associated anterior uveitis (AU), which recurs. The goal was to analyze cellular activation markers and adhesion molecules of T cells that infiltrate the eyes and spinal cord during acute and recurrent AU in actively and passively induced diseases simultaneously in the same animals.

EAE-AU was induced in Lewis rats by immunization with MBP in CFA, or by adoptive transfer of MBP-specific T-cell lines, and the signs of clinical EAE and AU was scored. Cells isolated from the iris-ciliary body were tested by flow cytometry for expression of CD4, CD8, CD45RC, T-cell receptor (TCR) Vbeta8.2, alpha4 integrin, L-selectin, CD44, and CD134.

Ocular T cells showed a significantly higher expression of CD62L (l-selectin) than did T cells in the spinal cord. In addition, a much lower percentage of infiltrating CD8(+) T cells was found in the eyes during AU. In passive transfer experiments, T-cell lines derived from acute and recurrent uveitis showing similar phenotypes differing in specificities but possessed the capacity of inducing both AU and EAE. Pretreatment of rats with effector CD4(+) T cell before MBP immunization did not induce suppression of EAE or AU. However, pretreatment with regulatory CD8(+) T cells significantly reduced the severity and duration of both EAE and AU.

T cells recruited into the inflamed eyes or central nervous system (CNS) are mainly activated/memory T cells expressing different levels of L-selectin. Regulatory CD8(+) T cells may contribute to the susceptibility of the eye to recurrent AU. The differences in phenotypes of T cells recruited simultaneously to two different organs suggest that microenvironment also plays a role in determining lymphocyte homing.