Epithelial HLA-DR expression in labial salivary glands in Sjögren's syndrome and non-specific sialadenitis.

The expression of the Class II major histocompatibility antigen HLA-DR was quantified in the epithelial cells of labial salivary glands from patients with Sjögrens Syndrome (SS) and compared with similar expression in glands showing non-specific sialadenitis and normal controls. In all glands more duct cells were positive than acinar cells but only in sialadenitis and SS was strong epithelial staining seen. The proportions of duct and acinar cells expressing HLA-DR were increased between normals and sialadenitis (P less than 0.01) and between sialadenitis and SS (P less than 0.001). However, for all cases increased expression of HLA-DR correlated to the increased proportion of inflammatory cells in the gland (P less than 0.01). The results indicate that although HLA-DR is expressed on the epithelial cells in the glandular lesions of SS, this is not specific as it is also seen in sialadenitis. This supports the view that such expression is secondary to an inflammatory infiltrate and may not be of importance in initiating autoimmune tissue damage.