The proportion and phenotypic changes of CD4+CD25-Foxp3+ T cells in patients with untreated rheumatoid arthritis.

OBJECTIVE: CD4+CD25+Foxp3+ regulatory T (Treg) cell-mediated immunosuppression is an essential mechanism of rheumatoid arthritis (RA). However, little is known regarding the specific role of CD4+CD25-Foxp3+ Treg cells in RA. This study aimed to investigate the frequency of circulating CD4+CD25-Foxp3+ Treg cells and their role in RA. METHODS: Sixty-one untreated RA patients and 40 healthy controls (HCs) were enrolled in this study. The proportion of CD4+CD25-Foxp3+ T cells and CD4+CD25+Foxp3+ Tregs; the levels of CTLA4, GITR, Helios, and ICOS; and the production of IL-17A, IFN-γ, and IL-10 were assessed by flow cytometry. The correlation of CD4+CD25-Foxp3+ T cells and CD4+CD25+Foxp3+ Tregs with the clinical indicators was conducted by Spearman correlation analysis. RESULTS: The proportion of CD4+CD25-Foxp3+ T cells was elevated in RA and positively correlated with disease activity. CD4+CD25-Foxp3+ T cells expressed less Helios and produced more IFN-γ than conventional Tregs in RA. Additionally, the proportion of CD4+CD25-Foxp3+ T cells was positively correlated with DAS28 score, IgG titer, and anti-CCP titer. CONCLUSIONS: These data indicate that CD4+CD25-Foxp3+ T cells in RA exhibit several different functional properties from conventional Tregs and are correlated with RA disease activity.