CD4+CD25-Foxp3+ T cells play a role in tuberculous hydrothorax rather than malignant hydrothorax

Background: Foxp3(+) T cells regulate inflammation and tumorigenesis. However, little is known about the role of different subsets of Foxp3(+) T cells in malignant or tuberculous hydrothorax. Methods: The numbers of CD4(+)CD25(+)Foxp3(+), CD4(+)CD25(-)Foxp3(+) T cells and the levels of some inflammatory cytokines in patients with tuberculous hydrothorax, malignant hydrothorax, and healthy controls (HCs) were examined by flow cytometry and ELISA. The potential association between the numbers of different subsets of Foxp3 + T cells and the values of clinical measures were analyzed. Results: The numbers of peripheral blood CD4(+)CD25(+)Foxp3(+) T cells were greater in malignant hydrothorax patients than in HCs, but fewer than those of hydrothorax in patients. The percentages of circulating IL-10(+) or LAP(+) CD4(+)CD25(+)Foxp3(+) T cells were higher than in the hydrothorax in patients with malignant hydrothorax. The numbers of circulating CD4(+)CD25(-)Foxp3(+) T cells were significantly fewer in patients with tuberculous hydrothorax than in HCs, and both the numbers of circulating CD4(+)CD25(+)Foxp3(+) and CD4(+)CD25(-)Foxp3(+) T cells were significantly fewer than in the hydrothorax in patients. Significantly higher percentages of circulating IL-10(+) or LAP(+) CD4(+)CD25(+)Foxp3(+) and CD4(+)CD25(-)Foxp3(+) T cells were detected in tuberculous hydrothorax patients. The numbers of CD4(+)CD25(+)Foxp3(+) and CD4(+)CD25(-)Foxp3(+) T cells were associated with hydrothorax adenosine deaminase (ADA) levels in tuberculous hydrothorax patients, while CD4(+)CD25(+)Foxp3(+) T cells were associated with carcino-embryonic antigen (CEA) in malignant hydrothorax patients. The concentrations of serum IL-6 and TGF-beta in the patients were significantly higher than that in the HCs, but lower than that in the corresponding hydrothorax. A similar pattern of IL-10 was observed in different groups, except that there was no significant difference in the levels of serum IL-10 between the tuberculous hydrothorax patients and HCs. Conclusions: CD4(+)CD25(-)Foxp3(+) T cells, which have lower inhibitory function than CD4(+)CD25(+)Foxp3(+)Foxp3(+) T cells, may play a role in tuberculous hydrothorax.