Background: Regulatory T cells (T(reg)) have been shown to play an important role in the regulation of hematopoietic activity. However, there is no information about the effect of T(reg) cells in the pathogenesis of polycythaemia vera (PV).
Methods: In this study, we investigated the percentage and function of T(reg) cells in the peripheral blood of 21 PV patients and 25 healthy donors. T(reg) cells were identified and characterized as CD4+CD25+ FOXP3+ by flow cytometry. The suppressive activity of CD4+CD25+ T(reg) cells was assessed by the proliferation and cytokine secretion of the co-cultured CD4+CD25- fractions.
Results: The results showed that the percentage of T(reg) cells in the peripheral blood of PV patients significantly increased compared to healthy controls ((10.93 +/- 4.02)% vs (5.86 +/- 1.99)%, P < 0.05). Moreover, the mRNA and protein expression of FOXP3 was higher in CD4+CD25+ T(reg) cells. Coordinately, when co-cultured with the activated CD4+CD25- cells, the CD4+CD25+ T(reg) cells showed enhanced suppressive function in PV. Yet, the underlying mechanism for the increased frequency and function of CD4+CD25+ T(reg) cells is still to be clarified.
Conclusion: T(reg) cells expansion might account for the abnormal T cell immunity in PV patients and thus contribute to the pathogenesis of PV.