T Cell Receptor Va-Vo Repertoire and Cytokine Gene Expression in Active Multiple Sclerosis Lesions

Sllml'l'lary Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system with presumed autoimmune etiology. A recent study has suggested the presence of a restricted T cell receptor (TCR) V,~ repertoire in MS lesions. The presence of such a restricted TCR repertoire at the site of inflammation would have important consequences for the pathogenesis and the ultimate treatment of MS. To further characterize the TCR V,~ and Vo repertoire in MS plaque tissue, we examined a series of 26 histologically well-characterized central nervous system (CNS) tissue specimens from six MS patients as well as samples from five normal postmortem cases and a case of subacute sclerosing panencephalitis. RNA was extracted from frozen sections and cDNAs were amplified by polymerase chain reaction using primers for TCR V,~ (V,~1-18) and V0 (Vt~1-19) gene families. This analysis demonstrated a broad TCR V,~-Vo repertoire in active lesions, while fewer TCR V genes were detected in chronic plaques and control samples. Even though a large number of TCR V~ and Vt~ gene segments were present in the majority of active lesions, there were clear differences in the TCR repertoire between plaques from the same case, suggesting that local events influence the TCR repertoire at the level ofT cell recruitment or T cell expansion. Examination of cytokine mRNAs demonstrated that IL-1 mRNA was present in the majority of acute and subacute plaques, while IL-2 and IL-4 mRNA were detected in only a few acute lesions. These data demonstrate that the TCIk repertoire in MS plaques is polyclonal. However, autoreactive oe/~/T cells thought to be critical in the initiation of the inflammatory process probably represent a minor fraction of T cells in active MS plaques and may use a limited number of TCR V gene segments for recognition of the autoantigen.