Increased frequency of regulatory T cells in the peripheral blood of patients with epithelial ovarian cancer

Ovarian carcinoma is one of the leading causes of cancer-related death among women. The purpose of this study was to investigate the frequency of CD4+CD25+CD127regulatory T cells (Tregs) in the peripheral blood of patients with epithelial ovarian cancer (EOC) and to explore their immune regulatory roles. 118 female patients with EOC and 30 healthy women were recruited. The percentage of CD4+CD25+CD127Tregs within the CD4+ T cell population in the peripheral blood was detected by flow cytometry. The relation between clinicopathologic factors and Tregs frequency was analyzed. To study the immunoregulatory capacity of CD4+CD25+CD127Tregs, cytokines produced by CD4+CD25+CD127Tregs was measured by ELISA and the proliferation of cells was measured by incorporation of [3H] thymidine. The percentage of CD4+CD25+CD127Tregs within the CD4+ T cell population in the peripheral blood of EOC patients was 5.34 ± 1.77%, significantly higher than that in healthy women. No correlation of Tregs frequency with tumor stage, differentiation grade and histological subtype was found. CD4+CD25+CD127Tregs derived from peripheral blood did not produce IFN-γ, but large amounts of IL-10. The isolated CD4+CD25+CD127Tregs notably decreased the proliferation of CD4+CD25T cells. We provide evidence of increased frequency of Tregs with potent immunosuppressive features in the peripheral blood of patients with EOC, which may be responsible for immune tolerance in EOC.