Immunohistochemical and ultrastructural demonstration of keratin in epi-myoepithelial islands of autoimmune sialadenitis in man.

Immunohistochemistry of salivary gland suggested that keratin is a specific marker of duct-epithelial cells and myosin for myoepithelial cells. Epi-myoepithelial islands found in some autoimmune sialadenitis, such as Sjögren's syndrome, were mainly composed of keratin-positive cells. Keratin filaments, with bundles and desmosome-attachments were invariably found in epithelial cells with electron microscopy. The islands contained no cells with myoepithelial characteristics. The findings show that there is no obvious participation of myoepithelial cells in the growth of the epi-myoepithelial islands.