To investigate the change of CD4+ CD25+ FoxP3+ regulatory T cells (Treg)in peripheral blood (PB)and synovial fluid (SF) in patients with rheumatoid arthritis (RA) and its role in RA immune tolerance imbalance.
The frequency of CD4+ CD25+ FoxP3+ Treg in PB and SF cells in active RA patients and healthy volunteers were determined using flow cytometry. The expression of FoxP3 gene in mononuclear cells was analyzed by real-time PCR. The correlation between the frequency of CD4+ CD25+ FoxP3+ Treg in PB cells and disease activity indices was evaluated.
(1) Active RA patients had a higher level of CD4+ CD25+ FoxP3+ Treg in SF cells (7.56% +/- 2.89%) than in PB cells (1.84% +/- 0.97%). Their level of CD4+ CD25+ FoxP3+ Treg in SF cells was also higher than that of healthy volunteers (2.19% +/- 0.54%). Anti-CCP antibody (ACPA) positive RA patients had a lower level of CD4+ CD25+ FoxP3+ Treg (1.40% +/- 0.63%) in PB cells compared with the ACPA negative RA patients (2.85 +/- 0.87%). (2) Active RA patients had a higher mRNA level of FoxP3 in SF mononuclear cells than those inactive RA patients and healthy volunteers (P < 0.01). (3) The frequency of CD4+ CD25+ FoxP3+ Treg in PB cells in active RA patients had no correlation with disease activity indices (P > 0.05).
Altered frequency of CD4+ CD25+ FoxP3+ Treg in SF cells of RA patients might contribute to RA immune tolerance imbalance in inflammatory joints.