Immunohistochemical investigations on the epimyoepithelial islands in lymphoepithelial lesions. Use of monoclonal keratin antibodies.

The histogenetic origin of cells in the epimyoepithelial islands occurring in patients with Sjoegren's syndrome has been investigated by using different monoclonal antibodies. The majority of cells in these islands reacted with broad specificity antibodies against keratins. The same cells are stained by a monoclonal antibody CKB1 which detects myoepithelial (basket) cells and basal cells (around the ducts) in normal salivary gland tissue, but which does not stain ductal epithelial cells. Conversely, the cells are not stained by the antibody CK5 which stains ductal epithelial cells in normal salivary gland tissue. The relation of the epimyoepithelial islands to the myoepithelial/basal cell system is thus demonstrated. Certain implications for practical use in surgical pathology are discussed.