On the myoepithelium of human salivary glands. An immunocytochemical study

This study investigated the immunocytochemical characteristics of normal myoepithelial cells (MECs) of human major and minor salivary glands using the LSAB method. Other human exocrine glands were used as controls. Immunoreactivity of MECs was observed exclusively with fully differentiated smooth muscle antibodies (a-SMA; SMMS-1; CALP; hCD) and with epithelial markers (cytokeratins) Ck14 and Ck17. This epithelial-muscular immunophenotype was similarly expressed in the MECs of other human exocrine glands used as control. In the salivary MECs, we did not observe evidence for neuroectodermic phenotype (S-100 protein, GFAP, NSE). On the contrary, positivity was observed for S-100 protein in Mecs of control glands (mammary, bronchial and sweat glands). Immunoreaction for extracellular matrix markers (fibronectin, laminin and collagen IV) and vimentin always were negative. Our data show that in normal "non transformed" MECs of the salivary glands the smooth muscle phenotype is in a state of complete differentiation, while the epithelial phenotype expresses only Ck14 and Ck17. This double and simultaneous immunoreactivity represents a differential marker of MECs from the epithelial basal cell (EBCs).