The status of lactoferrin and total iron binding capacity of human parotid saliva in Sjögren's syndrome

Sjögren's syndrome (SS) is chronic salivary gland disorder characterized by a reduction in salivary and lacrimal secretion. Elevation in salivary lactoferrin has been reported in SS patients. Fluctuation in the iron binding capacity of lactoferrin has been associated with cellular damage. Objective. The purpose of this study was to compare the levels of salivary lactoferrin, total iron, and iron binding capacity in Sjögren's syndrome (SS) patients and healthy controls. Methods. SDS-PAGE was used to examine the presence of lactoferrin in 102 patients and 20 healthy controls. A colorimetric assay was used to examine the level of total salivary iron and iron binding capacity in patients and controls. Results. A higher number of SS patients exhibited elevated levels of lactoferrin as compared to controls (86% vs. 20%, respectively). No significant difference was observed in the mean level of total iron in the saliva between patients and controls (12.6 μg/100 ml vs. 11.1 μg/100 ml, respectively). However the total iron binding capacity of lactoferrin was significantly lower among SS patients than healthy controls (38.2 μg/100 ml vs. 61.8 μg/100 ml, respectively), p = 0.019. Conclusion. The overall results of this study suggest a possible impairment of the iron binding capacity of saliva in SS patients. Such impairment may contribute to the cellular damage of the salivary glands observed in SS patients.