An immunoperoxidase investigation of S-100 protein in the epithelial component of Warthin's tumor.

Using the peroxidase-antiperoxidase (PAP) immunohistochemical method, we studied the epithelial component of Warthin's tumor of the human salivary gland with respect to the presence of S-100-protein-positive cells. The tumor epithelium consisted of two layers of oxyphilic cells (an apical layer of tall columnar cells and a basal layer of small cuboidal cells) and irregularly shaped, dendritic cells scattering throughout the neoplastic epithelial cells. Two types of the oxyphilic cells were devoid of the immunoreaction products for S-100 protein. However, in the epithelial layer of Warthin's tumor, S-100-protein-positive material was observed in the cytoplasm and nuclei of dendritic cells. They were more abundant in the lymphoid tissue than in the neoplastic epithelium. The morphologic appearance of these cells was identical to that of Langerhans' cells, which were absent from the normal human salivary glands. The presence of these cells, which have a special function of antigen presentation in immune responses, indicates that delayed hypersensitivity may be the main pathogenic factor in the development of Warthin's tumor.