Preferential activation of circulating CD8+ and gammadelta T cells in patients with active Behçet's disease and HLA-B51.

ABSTRACT

OBJECTIVE: To evaluate the activation status of circulating CD4+, CD8+, and gammadelta T cells in patients with active and inactive Behçet's disease (BD). METHODS: We studied 11 subjects with active BD, 28 with inactive BD, and 13 healthy controls. The expression of CD4, CD8, pan-gammadelta, Vdelta1, and Vdelta2 along with the early activation marker CD69 was analyzed by 3-color flow cytometry. RESULTS: Proportions of activated CD8+ and gammadelta T cells were significantly greater in patients with active BD than in those with inactive BD or healthy control subjects, but the proportion of activated CD4+ T cells did not differ among these 3 groups. In addition, significantly greater proportions of the Vdelta1+ and Vdelta2+ gammadelta T-cell subsets were activated in patients with active BD than in those with inactive BD or healthy controls; in active BD, the balance of activation between these subsets favored the Vdelta1+ T cells. No significant differences in these proportions were found between subjects with inactive BD and healthy controls. These findings were observed exclusively in patients with HLA-B51. A comparison of samples from 5 patients taken during active BD and after resolution of BD-related symptoms showed the proportions of activated CD8+ and gammadelta T cells dropped when the patients' BD became inactive. CONCLUSION: CD8+ and gammadelta T cells, rather than CD4+ T cells, were activated in vivo in patients with active BD and HLA-B51, but not in those with inactive BD, suggesting that these potentially cytotoxic T cells play a critical role in BD flares.