Ku protein and DNA strand breaks in lip glands of normal and primary Sjogren's syndrome subjects: Lack of correlation with apoptosis

The aim was to examine tissue expression of Ku protein in lower lip salivar y gland (LSG) biopsies from cases of primary Sjogren's syndrome (SS) and fr om normal subjects. Methods: immunohistochemistry was used with antibodies to Ku70/86 and also Ki67, PCNA and p53. In addition, the Klenow method was applied in order to detect evidence of apoptosis. Sections of hyperplastic tonsil served as additional controls. Results: in normal controls, LSG acin ar cells stained negatively whereas LSG excretory duct cell nuclei stained positively with Ku and Klenow and occasionally with PCNA but negatively wit h Ki67 and p53. In LSG focal sialadenitis of SS cases, some lymphocytic cel ls showed staining with Ku, Ki67, PCNA, Klenow and p53. In addition to duct cell Ku and Klenow as well as PCNA staining which was not much different f rom normals, a few ductal epithelial and also mononuclear cells stained wit h p53. In focal sialadenitis, some acinar cells showed staining with PCNA a s well as with Klenow. Conclusions: our findings in LSG biopsies of SS case s added little to an increased understanding about the pathogenetic mechani sms in the development of focal sialadenitis in SS. However. in normal LSG. ductal epithelial but not acinar cells seem to express a constitutively sp ecific Ku protein and Klenow profile, suggestive of DNA strand breaks but n ot clearly associated with ongoing apoptotic events. It may reflect an enha nced stress response, which may be pathogenetically important in the early events of focal sialadenitis development in primary Sjogren's syndrome.