Usage of Vβ3.3 T-cell receptor by myelin basic protein-specific encephalitogenic T-cell lines in the Lewis rat

T-cell receptor (TCR) β-chain usage in experimental autoimmune encephalomyelitis (EAE) seems to be much more heterogeneous than previously assumed even for a single autoantigen in an inbred animal strain. Owing to the lack of suitable antibodies, this has been demonstrated only at the RNA level so far. To characterize further the TCR elements used in the Lewis rat for the recognition of the main encephalitogenic region of myelin basic protein (MBP), BALB/c mice were immunized with T-cell hybridomas expressing non-Vβ8.2 TCR specific for guinea pig MBP peptide aa 68-88. Two B-cell hybridomas (clones C-A11 and F-D6) producing TCR Vβ3.3-specific monoclonal antibodies were selected. Specificity was demonstrated by RT-PCR and cloning of PCR products obtained from sorted T-cell lines and naive T cells. MBP- specific Vβ3.3 T cells used the L-S motif in the VDJ region, were associated with Vα2 or Vα8 chains, and specifically recognized MBP peptide aa 68-88. Vβ3.3 TCR-positive T cells were detected in all of a panel of six MBP- specific T-cell lines, although to a lesser degree than Vβ8.2 TCR-positive T cells. After intravenous injection of sorted Vβ3.3 T cells, animals developed EAE, and Vβ3.3-positive cells were found by immunocytochemical analyses in the spinal cord. Furthermore, treatment of EAE induced by immunization with MBP was more effective when a combination of anti-Vβ3.3 and anti-Vβ8.2 mAbs was used. These results confirm the functional role of TCR Vβ3.3 and thus underscore the heterogeneity of TCR usage in MBP- associated autoimmunity.