Determination of a CD4+CD25-FoxP3+ T cells subset in tumor-draining lymph nodes of colorectal cancer secreting IL-2 and IFN-γ

CD4(+)CD25(-)FoxP3(+) cells are a newly recognized subset of T cells which was first reported in autoimmune diseases. In our previous study, this subset was detected in tumor-draining lymph nodes (TDLNs) of patients with breast cancer. As little is known about their function in TDLNs of cancer patients, in this study, their frequency as well as their ability to produce interleukin (IL)-2, IL-10, or interferon (IFN)-gamma were investigated in TDLNs of colorectal cancer (CRC) patients. Mononuclear cells were isolated from lymph nodes of 13 patients with CRC using Ficoll-Hypaque gradient centrifugation. Cells were stimulated in vitro and stained with CD25, CD4, FoxP3, IFN-gamma, IL-10, and IL-2 or isotype matched antibodies and subjected to flow cytometry. The frequency of CD4(+)CD25(-)FoxP3(+)CD127(dim/-) cells was significantly lower than CD4(+)CD25(+)FoxP3(+)CD127(dim/-) population in TDLNs of CRC patients. The percentage of CD127(dim/-) cells and also the MFI of FoxP3 expression was significantly lower in CD4(+)CD25(-)FoxP3(+) in comparison with CD4(+)CD25(+)FoxP3(+) population. Moreover, CD4(+)CD25(-)FoxP3(+) cells contained higher percentages of IL-2- and IFN-gamma-producing cells than CD4(+)CD25(+)FoxP3(+) subpopulation. But, no difference was seen between two subsets in terms of IL-10 production. CD4(+)CD25(-)FoxP3(+) cells in TDLNs of CRC patients had lower suppressive and higher effector properties in comparison with CD4(+)CD25(+)FoxP3(+) conventional regulatory T cells.