Increased prevalence of regulatory T-cells in the peripheral blood of patients with gastrointestinal cancer.

BACKGROUND Although recent studies have shown that FoxP3 represent the most specific Treg marker only a few studies have reported on the presence of FoxP3(+)Treg in peripheral blood. PATIENTS AND METHODS Peripheral blood mononuclear cells (PBMC) were harvested from 37 healthy volunteers and 94 patients with gastrointestinal cancer. The prevalence of Treg co-expressing CD4(+)FoxP3(+) was analyzed using flow cytometry. RESULTS The prevalence of Treg in the peripheral blood of gastrointestinal cancer patients was significantly higher than that in healthy volunteers (p=0.012). In early stage I cancer, Treg levels tended to be higher than those in healthy volunteers (p=0.069); these levels were significantly reduced after tumor resection (p=0.0027). CONCLUSION The prevalence of Treg was increased in patients with gastrointestinal cancer, even in the early stages of the disease. Since Treg levels decreased after curative resection, it is possible that tumor cells may have induced and expanded the Treg pool.