OBJECTIVE To explore the effect of proinflammatory cytokines on the expression of human leucocyte antigen(HLA-DR) in epithelial cell of nasal polyps. METHODS The samples were from 23 patients with nasal polyps and 11 cases of normal inferior turbinates. The samples were fixed, paraffin-embeded and sectioned for observing distribution of HLA-DR positive cells. Nasal epithelial cells were obtained after enzymatic digestion and cell culture was performed for observing influences of interleukin (IL)-1 beta and tumor necrosis factor (TNF-alpha) to expression of HLA-DR of epithelial cells and the effect of dexamethasone(10(-5) mol/L). RESULTS The HLA-DR expression in epithelium was significantly stronger in nasal polyps than that in inferior turbinates. The expression of HLA-DR in cultured cells under stimulation of proinflammatory cytokines was increased compared with controls, but the expression was more intense in nasal polyps than that in inferior turbinates. Increased HLA-DR expression under stimulation of cytokines was reduced significantly by dexamethasone. CONCLUSIONS The epithelium is in a key position to participate in inflammatory and immunologic events in the airways. Epithelial cells potentially contribute to airway inflammation by antigen presentation and the production of proinflammatory cytokines.