Increased density of lymphocytes bearing γ/δ T-cell receptors in recurrent aphthous ulceration (RAU)

Abstract Lymphocytes bearing the T-cell receptor (TCR) γ/δ are increased in the peripheral blood of patients with recurrent aphthous ulcers (RAU) and Behcet's disease. In this study, we examined whether the density of TCR- γ/δ bearing lymphocytes was also increased locally in RAU lesions. Ten RAU lesions from ten patients were compared with ulcer-free mucosa from sites contralateral to the lesions, and with 10 samples of clinically healthy oral mucosa taken from 10 healthy volunteers. Samples were labeled with a panel of monoclonal antibodies specific to CD3, α/β TCR and γ/δ TCR in avidin-biotin-peroxidase complex (ABC) staining. Lymphocytes expressing γ/δ TCRs were very low in non-lesional mucosa and clinically healthy mucosa. By contrast, γ/δ T-cells were numerous and observed in all RAU lesions especially within the epithelium, inflammatory infiltrates and at perivascular locations. The count of γ/δ T-cells was high in connective tissue of RAU (200±126 cells/mm 2 ) compared with connective tissue of controls (4±4 cells/mm 2 ; P 2 ). Interestingly, the density of γ/δ T-cells was also high in the epithelium of RAU (70±34 cells/mm 2 ) compared with the epithelium of non-lesional mucosa (2.8±06 cells/mm 2 ; P 2 ; P γ/δ + T-cells among total CD3+ lymphocytes was increased in the connective tissue area from 4% and 5% in controls and non-lesional mucosa, respectively, to 19% in RAU. In epithelial areas, the average percentage was increased from 2% and 6% in controls and non-lesional mucosa, respectively, to 36% in RAU. These data showed that γ/δ T-cells are more numerous in RAU lesions and such an increase was purely restricted to RAU inflammatory areas.