The in vitro cytotoxic effect of leukocytes from patients with recurrent aphthous ulceration upon mouse 3T3 fibroblasts.

This study compared the in vitro cytotoxic activity against cultured NIH 3T3 mouse fibroblasts of peripheral blood leukocytes (PBL) from 13 patients with minor recurrent aphthous ulceration (RAU), 5 patients with non-aphthous oral ulceration and 23 age- and sex-matched healthy control subjects. Leukocytes from patients with RAU exerted a significantly greater degree of cytotoxicity towards the 3T3 cells than did those of control subjects. This enhanced cytotoxicity was abrogated by depletion of PBL bearing the CD5 antigen (T-lymphocytes). In contrast, PBL from patients with non-aphthous oral ulceration failed to exert an enhanced cytotoxic activity against 3T3 fibroblasts, when compared to PBL from healthy control subjects. It was concluded that PBL from patients with RAU exert a significantly enhanced cytotoxicity towards an unrelated xenogeneic target cell. This activity is a specific feature of RAU and in the assay system described appears to be mediated by T-lymphocytes.