The aim of this study was to examine the presence of the complement regulatory proteins protectin (CD59), decay accelerating factor (CD55), membrane cofactor protein (CD46) and clusterin (SP-40,40) in connection with the autoimmune exocrinopathy in Sjögren's syndrome (SS).
Labial salivary gland biopsy specimens and saliva samples were obtained from SS patients and healthy subjects. The tissue expression of these proteins was assessed by ABC immunoperoxidase techniques. Saliva was analysed by immunoblotting methods.
Tissues from healthy subjects expressed CD59 and CD46 on the apical/luminal surfaces of acinar and ductal epithelial cells. CD59, CD55, and SP-40,40 were expressed in interstitial tissues. In SS tissues, the expression of CD55, CD59, CD46 and SP-40,40 was up-regulated, following the same patterns of tissue localization as the controls. CD46 and SP-40,40 exhibited a much higher staining intensity in SS patients compared to controls. CD55, CD59 and SP-40,40 were present at high concentrations in saliva from SS patients.
The presence of complement regulators in our SS patients' saliva and the high expression of these proteins in inflamed salivary gland tissue followed the inflammatory reaction. These regulators may be involved in protecting the exocrine glands from complement mediated injury.