T-lymphocyte subsets in oral mucosa of patients with recurrent aphthous ulceration.

In the present study, the proportion of mononuclear cells and percentages of CD4+ (OKT4+) and CD8+ (OKT8+) were determined in clinically healthy buccal mucosa in patients with recurrent minor aphthous ulceration (RAU) (n = 43) during active and inactive disease as compared with RAU-free controls (n = 15). In lamina propria, the total number of mononuclear cells and subset percentages were determined histologically and immunohistochemically. Mononuclear cell counts in patient specimens were significantly lower than in the control group. CD4+ percentages were not significantly different between controls and patients. CD8+ percentages of the patients were significantly increased during active RAU, but not during inactive RAU as compared with controls. In proportion to the total number of mononuclear cells, CD4+ and CD8+ cell counts per 0.25 mm2 were significantly lower in the patients during both active and inactive disease as compared with controls. Thus, RAU seems characterized by reduced numbers of mononuclear cells, including T-lymphocytopenia in the oral mucosa as such, features that appear more pronounced during active disease than during quiescence.