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

Abstract

Lymphocytes bearing the T-cell receptor (TCR) gamma/delta 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-gamma/delta 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, alpha/beta TCR and gamma/delta TCR in avidin-biotin-peroxidase complex (ABC) staining. Lymphocytes expressing gamma/delta TCRs were very low in non-lesional mucosa and clinically healthy mucosa. By contrast, gamma/delta T-cells were numerous and observed in all RAU lesions especially within the epithelium, inflammatory infiltrates and at perivascular locations. The count of gamma/delta T-cells was high in connective tissue of RAU (200 +/- 126 cells/mm2) compared with connective tissue of controls (4+/-4 cells/mm2; P<0.0001) or non-lesional mucosa (5+/-7 cells/mm2). Interestingly, the density of gamma/delta T-cells was also high in the epithelium of RAU (70+/-34 cells/mm2) compared with the epithelium of non-lesional mucosa (2.8+/-06 cells/mm2; P<0.0001) or epithelium of healthy controls (1.2+/-1.5 cells/mm2; P<0.0001). Moreover, the mean percentage of gamma/delta+ 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 gamma/delta T-cells are more numerous in RAU lesions and such an increase was purely restricted to RAU inflammatory areas.