Expression of Cell Proliferation-associated Nuclear Antigen (Ki-67) in Recurrent Aphthous Ulcers(RAU).

Abstract

The histological features of recurrent aphthous ulcer (RAU) are consistent with increased number and activation of T cells in the diseased areas. A previous study suggested that 13-23% of the cells express IL-2 and transferrin receptors, which implies potential for local proliferation. The aim of the study was to to evaluate the proliferation activity in 10 RAU lesions compared to 9 oral traumatic ulcer (TU) lesions. Demonstration of proliferating cells was performed by application of affinity-purified rabbit anti-human Ki-67 antibodies in avidin-biotin-peroxidase complex (ABC) staining to both RAU and TU biopsies. We found that the basal/suprabasal layers of RAU epithelium away from the ulcer contained 30% more proliferating cells (127±24 vs 97±19 cells/0.2mm², P2) of the infiltrating inflammatory cells in RAU lesions were Ki-67-positive proliferating cells, compared to only 3±1% (37±14 cells/0.2 mm²) in TU inflammatory infiltrates. These findings suggested that the mitotic activity is increased in RAU epithelium and that the relatively longer persistence of RAU cannot be explained by a lack of new epithelial cell production. Furthermore, mononuclear inflammatory cells replication in situ represent one mechanism for the expansion of the inflammatory cell infil-trates at sites of RAU and TU lesions.