Diversity of γδ T cells in patients with Behcet's disease is indicative of polyclonal activation

OBJECTIVE: Behcet's disease (BD) is a multisystemic disease, with vasculitic lesions in the oral and genital mucosa, eyes, joints, skin and brain. We have previously found that gamma delta T cells are increased in peripheral blood of BD patients. The aim of this study was to investigate the extent of gamma delta T cells in oral biopsies from BD patients with special emphasis on the restriction of V gamma and V delta usage. PATIENTS AND METHODS: Expression of V gamma and V delta chains on peripheral blood gamma delta T cells from 31 BD patients and 19 healthy controls was analysed by flow cytometry and the expression of V gamma and V delta chains in nine ulcerated and eight non-ulcerated oral mucosa from BD patients and non-ulcerated oral mucosa from three healthy controls was analysed by immunohistochemistry. RESULTS: V gamma 9 and V delta 2 were the predominant chains expressed in peripheral blood of BD patients, although other V gamma and V delta chains were also expressed. The presence of gamma delta T cells was only observed in the ulcerated oral mucosa but not in the non-ulcerated mucosa from the BD patients, and not in the non-ulcerated mucosa from the healthy controls. These gamma delta T cells showed no preferential expression of any of the V gamma or V delta chains. CONCLUSION: These data suggest a polyclonal rather than oligoclonal activation of the gamma delta T cells. This may indicate that during repeated inflammation of the oral mucosa, the gamma delta T cells are responding to a wide variety of antigenic stimuli with consequent expansion of gamma delta T cells expressing various V gamma and V delta chains and that different antigenic stimuli or responses may be responsible for the clinical heterogeneity of the disease.