Restricted TCR Valpha gene rearrangements in T cells recognizing an immunodominant peptide of myelin basic protein in DR2 patients with multiple sclerosis.

T cell responses to myelin basic protein (MBP) are thought to play an important role in the pathogenesis of multiple sclerosis (MS). The response to the 83-99 region of MBP represents a dominant response to MBP in patients with MS and is associated with HLA-DR2 that is linked with susceptibility to MS. Although T cell clones reactive to various regions of MBP have been found to exhibit heterogeneous TCR Vbeta gene usage in patients with MS, it is unclear whether T cell clones uniformly recognizing the 83-99 peptide of MBP in the context of the same DR molecule would have restricted TCR V gene rearrangements and recognition motifs. In this study, a panel of DR2- or DR4-restricted T cell clones specific for the MBP83-99 peptide were derived from 11 patients with MS and examined for TCR V gene usage by PCR and the recognition motifs using analog peptides. Our study revealed that despite a few T cell clone pairs having similar recognition motifs and shared sequence homology in the CDR3, the overall recognition motifs of MBP83-99-specific T cells were considerably diverse. Interestingly, the DR2-restricted T cell clones displayed a biased V gene usage for Valpha3 and Valpha8, while Vbeta gene rearrangements were highly heterogeneous. This study provided experimental evidence suggesting a limited heterogeneity in TCR Valpha gene rearrangements of MBP-reactive T cells in DR2 patients with MS.