Altered frequency of CD4+CD25-Foxp3+ T cells in patients with systemic lupus erythematosus

Objective: To investigate the expression pattern of circulating CD4+CD25-Foxp3+ T cells from the patients with systemic lupus erythematosus (SLE) in order to explore their role in disease pathogenesis.

Methods: Lupus patients with new-onset active disease (n=15) and inactive disease (n=10) as well as healthy volunteers (n=15) were enrolled. The frequency of circulating CD4+CD25-Foxp3+ T cells and the level of CD127 expression on these cells were analyzed by flow cytometry. FOXP3 gene expression in purified CD4+CD25- T cell subset by MACS was assessed by real-time PCR.

Results: The percentages of CD4+CD25-Foxp3+ T cells within CD4+ lymphocytes in active patients, inactive patients and healthy controls were (9.89+/-0.85)%, (7.11+/-0.86)% and (3.35+/-0.31)%, respectively. The frequency of CD4+CD25-Foxp3+ T cells in these lupus patients correlated positively with their SLEDAI (P=0.0008). Moreover, Foxp3 expressions, at both mRNA and protein levels, were increased in the purified CD4+CD25- T cell population from active patients compared to healthy controls (P<0.01). Most CD4+CD25-Foxp3+ T cells were found to be CD127(low).

Conclusions: Altered frequency of CD4+CD25-Foxp3+ T cells in lupus patients might attribute to the resistant effect on Treg suppression, one mechanism accounting for T cell loss of peripheral tolerance in the pathogenesis of SLE.