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

Lymphocytes bearing the T-cell receptor (TCR) gamma/delta are increased in the peripheral blood of patients with recurrent aphthous ulcers (RAU) and B ehcet's disease. In this study, we examined whether the density of TCR-gamm a/delta bearing lymphocytes was also increased locally in RAU lesions. Ten RAU lesions from ten patients were compared with ulcer-free mucosa from sit es contralateral to the lesions, and with 10 samples of clinically healthy oral mucosa taken from 10 healthy volunteers. Samples were labeled with a p anel of monoclonal antibodies specific to CD3, alpha/beta TCR and gamma/del ta TCR in avidin-biotin-peroxidase complex (ABC) staining. Lymphocytes expr essing gamma/delta TCRs were very low in non-lesional mucosa and clinically healthy mucosa. By contrast, gamma/delta T-cells were numerous and observe d in all RAU lesions especially within the epithelium, inflammatory infiltr ates and at perivascular locations. The count of gamma/delta T-cells was hi gh in connective tissue of RAU (200+/-126 cells/mm(2)) compared with connec tive tissue of controls (4+4 cells/mm(2); P<0.0001) or non-lesional mucosa (5+/-7 cells/mm(2)). Interestingly, the density of <gamma>/delta T-cells wa s also high in the epithelium of RAU (70+/-34 cells/mm(2)) compared with th e epithelium of non-lesional mucosa (2.8+/-06 cells/mm(2); P<0.0001) or epi thelium of healthy controls (1.2+/-1.5 cells/mm(2); P<0.0001). Moreover, th e 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 aver age percentage was increased from 2% and 6% in controls and non-lesional mu cosa, respectively, to 36% in RAU. These data showed that gamma/delta T-cel ls are more numerous in RAU lesions and such an increase was purely restric ted to RAU inflammatory areas.