Analysis of T-cell receptor usage in myeloperoxidase--antineutrophil cytoplasmic antibody-associated renal vasculitis.

BACKGROUND: Bacterial superantigens produced by Staphylococcus aureus may be associated with the onset of proteinase-3 antineutrophil cytoplasmic antibody (PR3-ANCA)-associated vasculitis, including Wegener's granulomatosis. We investigated T-cell subsets to assess the superantigens present in patients with myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA)-associated vasculitis.
METHODS: Peripheral-blood mononuclear cells (PBMC) obtained from 40 normal controls and ten patients with MPO-ANCA-associated vasculitis were stained with fluorescence-labeled monoclonal antibodies against T-cell markers, including 17 variable regions of T-cell receptor beta-chains (TCR-Vbeta) and were then analyzed using flow cytometry.
RESULTS: Among PBMCs, the percentage of CD3(+) cells from patients with MPO-ANCA-associated vasculitis was significantly lower than that from normal controls, but there were no differences between the two groups in the percentage of CD19(+) cells or CD16(+) cells. Although there were no differences regarding the overall percentage of CD4(+) cells between the two groups, the percentage of CD4(+)CD45RO(+) cells in patients with MPO-ANCA-associated vasculitis was significantly higher than that in normal controls, and percentages of CD4(+)CD45RO(+)HLA-DR(+) and CD4(+)CD45RO(+)CD62L(low) cells in patients with MPO-ANCA-associated vasculitis were also significantly increased. There was no significant difference between the two groups in terms of the usage of the 17 different TCR-Vbeta regions.
CONCLUSION: There was no difference in bacterial superantigens between controls and MPO-ANCA-associated vasculitis patients because of the absence of specific usage of TCR-Vbeta regions. Given the elevated levels of memory T cells, conventional antigens rather than superantigens may be associated with the pathogenesis of MPO-ANCA-associated vasculitis.