HLA-DR antigens in normal, inflammatory, and neoplastic salivary glands

A monoclonal antibody to HLA-DR antigens that is reactive in formalin-fixed tissues was used with the immunoperoxidase method to evaluate 212 salivary gland lesions (normal, nonspecific, and autoimmune inflammatory, benign, and malignant tumors). Results of immunostaining showed that (1) intercalated ducts, myoepithelial cells, and acinous cells of normal salivary glands express HLA-DR antigens, (2) autoimmune salivary gland disease results in greater HLA-DR expression than that seen in nonspecific inflammatory lesions or normal glands, (3) stromal cells associated with benign and malignant salivary gland tumors express HLA-DR antigens, and (4) numerous benign and malignant salivary gland tumors express HLA-DR antigens. It was of interest that lymphocyte-rich Warthin's tumors displayed epithelial immunoreactivity, whereas oncocytomas devoid of a lymphocytic component were invariably negative. This suggests a lymphocyte-mediated role in salivary epithelial HLA-DR expression. It appears that HLA-DR expression is both a normal and an inducible phenomenon in salivary glands, salivary gland neoplasia, and the desmoplastic host response. There is no discriminatory role in the immunologic detection of HLA-DR for differential diagnosis of salivary gland tumors.