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 Sjogren'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 α-dystroglycan. Results Only acinar cells contained Int al and a2 subunits. This staining was interrupted but strong in controls, but very weak in SS. Both acinar and ductal cells contained Int a3, a6, β1 and β4 and Lutheran blood group antigen and ductal cells also contained α-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 α3β1, α6β1 and α6β4 integrin-receptors and Lutheran blood group antigen and α-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 α1β1 and α2β1 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.