Increased frequencies of CD4+ CD25+ FOXP3+ regulatory T cells in human nasal inverted papilloma.

Background: The purpose of this study was to investigate the presence of CD4(+) CD25(+) FOXP3(+) regulatory T (Treg) cells both in peripheral blood and local tumors in patients with nasal inverted papilloma (NIP).

Methods: By using flow cytometry, the frequencies of CD4(+) CD25(+) FOXP3(+) Treg cells in both peripheral blood and tissues from 18 patients with NIP and 8 control subjects were determined. CCL22 and CCL17 proteins in NIP tumors were analyzed by using enzyme-linked immunosorbent assay. The suppressive capacity of Treg cells was estimated by WST-8 and enzyme-linked immunosorbent assay (ELISA; interferon-gamma [IFN-γ] and interleukin-4 [IL-4]) analysis.

Results: Patients with NIP showed increased CD4(+) CD25(+) FOXP3(+) Treg cell frequencies in tumor tissues and CD4(+) T cell fraction rather than in peripheral blood. CCL22 increased in NIP tumors. Phytohemagglutinin (PHA)-induced proliferation and cytokine production of CD4(+) CD25(-) T cells were suppressed equally well by CD4(+) CD25(high) cells from both patients with NIP and controls.

Conclusion: Our study demonstrated the increased frequencies of CD4(+) CD25(+) FOXP3(+) Treg cells in NIP tumors, which might be influenced by CCL22.