To investigate the expression of forkhead box protein P3 (Foxp3) in the peripheral blood and salivary gland of patients with Sjogren's Syndrome (SS).
Reverse transcription polymerase chain reaction (RT-PCR) was used to examine Foxp3mRNA expression in the CD(4)(+) T cells and the salivary glands from 6 primary SS patients and 6 normal controls. Serial sections of biopsied salivary gland (SG) were examined with immunohistochemistry, using monoclonal mouse anti-human CD(4) and Foxp3 in 6 healthy controls and 31 primary SS patients.
Significant difference in the number of infiltrating CD(4)(+) T cells was noted in the salivary glands of the patients and controls, but Foxp3(+)CD(4)(+) T cells were almost absent in those biopsy samples. Foxp3mRNA expression in the blood of SS patients was significantly lower than that in normal controls (0.21 +/- 0.17 vs 1.32 +/- 0.38, P < 0.0184). Foxp3mRNA expression was not detectable in the tissue of the salivary glands (n = 6).
The absence of Foxp3(+)CD(4)(+) T cells in salivary glands with reduction of Foxp3mRNA expression in peripheral blood suggests an important role of Foxp3 in the pathogenesis of SS.