A PATHOGENIC ROLE FOR GAMMA-DELTA T-CELLS IN RELAPSING-REMITTING EXPERIMENTAL ALLERGIC ENCEPHALOMYELITIS IN THE SJL MOUSE

Previous studies have detected gamma delta T cells in multiple scleros is and experimental allergic encephalomyelitis (EAE) lesions but their role remains obscure. In the present study, we assessed gamma delta T cell dynamics and distribution in spleen and central nervous system ( CNS) from mice with relapsing-remitting EAE, and studied the effect of depleting these cells on clinical and pathologic expression of diseas e using the mAb GL3. By immunohistochemistry and FACS analysis, striki ng disease-related changes were observed in the gamma delta T cell pop ulation in the CNS. FACS analysis showed that while gamma delta T cell s remained low in the spleen (similar to 2% total CD3(+) T cells) at a ll stages, in the CNS they increased to similar to 12% at the height o f the acute attack, fell to similar to 5% during the recovery phase, b ut rose again to similar to 12% during the chronic phase. In animals i n which gamma delta T cells were depleted immediately before the onset of acute disease, or during the chronic stage, a striking and signifi cant reduction in the severity of the clinical signs was observed that was associated with a decrease in the percentage of CD3(+)/gamma delt a T cells in the CNS. In depleted animals a statistically significant reduction in inflammation and demyelination was noted during the acute stage, but only marginal effects on these disease parameters were fou nd in the chronic phase. Taken together, the data support the conclusi on that gamma delta T cells play an important role in the pathogenesis of EAE in mice during both acute and chronic/progressive phases of th e disease process.