On the myoepithelium of human salivary glands. An immunocytochemical study

This study investigated the immunocytochemical characteristics of normal my oepithelial cells (MECs) of human major and minor salivary glands using the LSAB method. Other human exocrine glands were used as controls. Immunoreac tivity of MECs was observed exclusively with fully differentiated smooth mu scle antibodies (alpha -SMA; SMMS-1: CALF; 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 con trol. In the salivary MECs, we did not observe evidence for neuroectodermic phenotype (S-100 protein, GFAP, NSE). On the contrary: positivity was obse rved for S-100 protein in MECs of control glands (mammary, bronchial and sw eat glands). Immunoreaction for extracellular matrix markers (fibronectin, laminin and collagen IV) and vimentin always were negative. Our data show t hat in normal "non transformed" MECs of the salivary glands the smooth musc le phenotype is in a state of complete differentiation. while the epithelia l phenotype expresses only Ck14 and Ck17. This double and simultaneous immu noreactivity represents a differential marker of MECs from the epithelial b asal cell (EBCs).