RESUMEN
The objective of this study was to evaluate human leucocyte antigen-DR [HLA-DR] expression in nasalpolyp epithelium compared with their surrounding normal nasal mucosa as well as activated T helper cells [CD4 positive] in order to obtain a clue concerning the immunological mechanisms that are possibly relevant to the nasal polyp pathogenesis. By means of immunohistochemical methods, samples from 16 patients with nasal polyps were investigated. The histomorphologic analysis revealed nonallergic nasal in 12 cases, while allergic polyps in only 4 cases. Epithelial changes were observed in 10 of both allergic and nonallergic polyp types. They included epithelial hyperplasia [four cases], goblet metaplasia [two cases] and squamous metaplasia [four cases]. Nasal polyps with average normal epithelial thickness were present in six cases. HLA-DR antigen molecules were significantly highly expressed in the normal respiratory nasal epithelial cells as well as in nasal polyps with an average normal epithelial thickness. However, they significantly reduced in nasal polyps associated with epithelial hyperplasia, goblet cell metaplasia and squamous cell metaplasia. On the other hand, submucosal inflammatory cells exhibited a high expression of HLA-DR in nasal polyps versus normal submucosa. The activated T helper cells [CD4 positive] were increased in nasal polyps versus normal nasal mucosa, with no significant difference between allergic and nonallergic polyps