Acinar epithelial cell laminin-receptors in labial salivary glands in Sjögren's syndrome.

OBJECTIVE To analyze the epithelial cell-basement membrane attachment, in particular in the secretory end pieces (responsible for secretion of saliva) and in Sjögren's syndrome (SS) characterized by acinar cell failure. METHOD Immunohistochemistry with laminin receptor chain-specific monoclonal antibodies to integrin (Int) subunits, Lutheran blood group antigen and alpha-dystroglycan. RESULTS Only acinar cells contained Int alpha1 and alpha2 subunits. This staining was interrupted but strong in controls, but very weak in SS. Both acinar and ductal cells contained Int alpha3, alpha6, b1 and b4 and Lutheran blood group antigen and ductal cells also contained alpha-dystroglycan. These staining patterns were similar in SS and controls. CONCLUSIONS Binding of the acinar and ductal cells to the basement membrane laminins seems to be mediated by Int alpha3b1, alpha6b1 and alpha6b4 integrin-receptors and Lutheran blood group antigen and alpha-dystroglycan non-integrin receptors. This structure-supporting system is intact in SS, compatible with the maintenance of the tubuloalveolar architecture of the SS glands. The irregular staining pattern of the acinus-specific Int alpha1b1 and alpha2b1 was compatible with a regulated signaling role, which was apparently impaired in SS. Indeed, their laminin counterparts (Lm -1/111 and -2/211) are also aberrant in SS revealing this as the central cell-matrix defect in the syndrome.