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 gammadelta T cells are increased in peripheral blood of BD patients. The aim of this study was to investigate the extent of gammadelta T cells in oral biopsies from BD patients with special emphasis on the restriction of Vgamma and Vdelta usage. PATIENTS AND METHODS: Expression of Vgamma and Vdelta chains on peripheral blood gammadelta T cells from 31 BD patients and 19 healthy controls was analysed by flow cytometry and the expression of Vgamma and Vdelta 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: Vgamma9 and Vdelta2 were the predominant chains expressed in peripheral blood of BD patients, although other Vgamma and Vdelta chains were also expressed. The presence of gammadelta 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 gammadelta T cells showed no preferential expression of any of the Vgamma or Vdelta chains. CONCLUSION: These data suggest a polyclonal rather than oligoclonal activation of the gammadelta T cells. This may indicate that during repeated inflammation of the oral mucosa, the gammadelta T cells are responding to a wide variety of antigenic stimuli with consequent expansion of gammadelta T cells expressing various Vgamma and Vdelta chains and that different antigenic stimuli or responses may be responsible for the clinical heterogeneity of the disease.