Immunity to TCR peptides in multiple sclerosis: II. T cell recognition of Vβ5.2 and Vβ6.1 CDR2 peptides

The biased expression of Vβ5.2 and Vβ6.1 by T cells specific for myelin basic protein (BP) has led to our use of TCR peptides from these V gene sequences to induce anti-TCR immunity in patients with multiple sclerosis (MS). Injection of Vβ5.2-39-59 or Vβ6.1-39-59 peptides significantly increased the peptide specific T cell frequency in 7 of 11 MS patients, often with an accompanying delayed hypersensitivity reaction at the injection site. Here, we validate these cellular immune responses by characterizing TCR peptide specific T cells from an MS patient with biased Vβ5.2 expression in BP reactive T cells before treatment with TCR peptides, and from two MS patients in whom the frequencies of anti-TCR peptide specific T cells were significantly boosted after injection with low doses of TCR peptides. In both cases, T cell lines were established with relative ease, especially after boosting with the peptides. A Vβ5.2-39-59 reactive line responded selectively to the boosting peptide and was restricted by both MHC class I (HLA-B7) and MHC class II (HLA-DR2) molecules. Characterization of 22 clonal isolates revealed that the responding T cells were predominantly activated CD4⁺CD8(lo), circulating memory cells restricted by either HLA-B7 or HLA- DR2, that utilized mainly Vβ4, Vβ6, Vβ12, and Vβ14, but not Vβ5.2 in their TCR. T cell isolates specific for Vβ6.1-39-59 possessed similar characteristics but contained specificities cross-reactive with an N-terminal sequence on Vβ5.2-39-59. Upon stimulation with peptide or Con A, the TCR peptide specific T cell lines had increased message production for IFN-γ, GM-CSF, IL-4, IL-5, and to a lesser degree, IL-2. This lymphokine mRNA profile differed from a BP-specific T cell line that produced message for IFN-γ and GM-CSF but low or absent levels of IL-4 and IL-5. The extensive parallels between human T cells specific for Vβ5.2 and Vβ6.1 CDR2 peptides and rat T cells specific for Vβ8.2 CDR2 peptide that are highly protective against experimental encephalomyelitis strengthen the rationale for the therapeutic use of TCR peptides in human autoimmunity.