Oral mucosal Langerhans cells express DR and DQ antigens.

The expression of the Class II antigens HLA-DR and HLA-DQ in human oral mucosa was examined in health and in the presence of inflammation. DQ antigens were detected on dendritic intra-epithelial cells which expressed the Langerhans cells (LC) phenotype T6+, DR+. In healthy gingiva, DR and DQ were co-expressed on Langerhans cells, whereas in an experimental gingivitis (day 8), more LC expressed DR than DQ. Absolute LC numbers were increased in inflammation. Traumatic ulceration of the buccal mucosa resulted in a decrease in the density of T6-, DR-, and DQ-positive cells. Repopulation of migrating and regenerated epithelium was complete 10 days after ulcer induction. Disparity between DR and DQ expression was seen in both normal buccal mucosa and throughout the ulcer healing period. These results are in agreement with the reported sequence of Class II antigen expression on lymphoid cells.