The predominance of Th17 lymphocytes and decreased number and function of Treg cells in preeclampsia.

The aim of this study was to estimate the prevalence of CD3(+)CD4(+) T lymphocytes producing IL-17, IL-2, IFN-γ, and IL-4, plus CD4(+)CD25(+)FoxP3(+) T regulatory (Treg) cells, in peripheral blood of patients with preeclampsia and healthy women in the third trimester of normal pregnancy. Another purpose was to assess the immunosuppressive activity of Treg cells from patients with preeclampsia compared with controls. Thirty-four preeclampsia patients and 27 healthy pregnant women were included. The percentages of CD4(+)CD25(+)FoxP3(+) Treg cells and CD3(+)CD4(+) T lymphocytes with intracellular expressions of cytokines were estimated using monoclonal antibodies and flow cytometry. In vitro functional assays were performed using a Treg Cell Isolation Kit and (3)H-thymidine incorporation assays. The percentage of CD3(+)CD4(+) T lymphocytes producing IL-17A was significantly higher in preeclampsia than in healthy, normotensive pregnant women in the third trimester (p<0.001). The population of CD4(+)CD25(+)FoxP3(+) Treg cells was significantly lower in the study group compared with controls (p<0.05). There was no change in the stimulation index of CD3(+)CD4(+)CD25(-) T lymphocytes from preeclampsia patients without Treg cells and after addition of autologous Treg cells. In normal pregnancy, the stimulation index of CD3(+)CD4(+)CD25(-) T lymphocytes was significantly higher without Treg cells compared with the response after addition of autologous Treg cells (p<0.05). The results suggest up-regulation of the Th17 immune response in preeclampsia. The decreased number and function of Treg cells may be responsible for activating the inflammatory response characteristic of this disorder. In preeclampsia, the predominance of Th17 immunity could act through modulating the Th1/Th2 immune balance.