The distribution of immunostaining in normal major salivary gland and in 12
pleomorphic adenomas was studied using monospecific
monoclonal antibodies to a number of cytokeratins, including
cytokeratin 14, to smooth muscle actin and
vimentin. A number of these
antibodies enabled a distinction to be made between structural components of the normal gland, and to relate this to the different structures of
pleomorphic adenomas. In the normal gland, the
luminal duct cells expressed cytokeratins 7, 8, 18 and 19. Three
antibodies were of particular value for the characterization of normal myoepithelial and basal cells; while the antibody to smooth muscle actin and the
cytokeratin antibody Ks8.12 mutually exclusively stained the myoepithelial (basket) cells and the basal duct (light) cells, respectively, the recently established monospecific
antibodies to
cytokeratin 14 showed specific immunostaining with both cell types. These three
antibodies left
luminal cells virtually unstained. Ck 13 was found occasionally in single
luminal excretory duct cells.
Antibodies to cytokeratins 1/2, 10 and 10/11 did not show any staining in the normal gland. In the
pleomorphic adenomas, the staining pattern of the two-layered tubular formation resembled that of the normal gland ducts: tumour
luminal cells showed the characteristic, although more irregular, expression of cytokeratins 7, 8, 18 and 19; the outer cells resembled normal ductal basal cells with their anti-
cytokeratin 14/Ks8.12-
epitope staining and in that they virtually lacked staining for smooth muscle actin. Trabecular formations and cells in myxoid areas were reactive with Ks8.12 and for
cytokeratin 14, occasionally also for cytokeratins 7, 18 and 19. Epidermoid cell islets expressed mainly
cytokeratin 14 and inconsistently the squamous epithelial
cytokeratin 13 and the epidermal
cytokeratin 10/11.
Vimentin was found in cells of myxoid areas. The results support the postulate that some of the normal duct basal cells act as reserve cells and can give rise to tumour formation with a primitive myxoid or trabecular pattern and a more differentiated tubular or epidermoid configuration.