T-cell expansions with conserved T-cell receptor β chain motifs in the peripheral blood of HLA-DRB1*0401 positive patients with necrotizing vasculitis

T lymphocytes are implicated in the pathogenesis of systemic vasculitis such as Wegener's granulomatosis (WG) and polyarteritis nodosa (PAN). In the present study, we have characterized in detail the T-cell receptor (TCR) of peripheral blood T cells from eight vasculitis patients of known HLA class II genotypes. We used flow cytometry to outline the exact TCR V gene expression, complementarity determining region 3 (CDR3) fragment analysis to estimate the degree of clonality and cDNA sequencing to define the exact TCR α or β chain sequences. The TCR CDR3 region interacts with antigenic peptides presented by HLA molecules, and it is normally immensely diverse. It was therefore of particular interest to identify a common dominating TCR BV8- F/L-G-GA/Q-G-J2S3 β chain sequence in the CD4⁺ T cells of four unrelated vasculitis patients. Furthermore, this BV8-associated CDR3 motif was linked to the HLA-DRB1*0401 allele, as well as to active disease and/or an established BV8⁺ CD4⁺ T-cell expansion. In contrast, age- and HLA-matched patients with rheumatoid arthritis did not harbor the described BV8 motif. These results strongly suggest that BV8⁺ CD4⁺ T cells with the described CDR3 motif recognize a specific antigen presented by DR4 molecules, indicating the existence of a common vasculitis-associated antigen.