Epithelial expression of HLA-DR antigens in laryngeal papillomas with a dense inflammatory reaction

Thirty six laryngeal papillomas taken from 11 children and 10 adults were investigated with an indirect immunofluorescence technique for the occurrence of T cell subsets, Langerhans cells and HLA-DR antigen using specific monoclonal antibodies. A mild local cellular immune response was preferentially associated with juvenile laryngeal papillomas, whereas a more intense inflammatory reaction with T8 cell infiltration and large amounts of Langerhans cells in the chorion and the epithelium was observed in adult lesions. Some lesions either from adults or children characterized by high densities of lymphoid and dendritic cells exhibited the expression of DR antigen by epithelial cells. This result may suggest either a role of lymphokines released by activated T cells or a direct effect of viral infection on epithelial cells inducing DR antigen in laryngeal papillomas.