Circulating and decidual Th17 cell levels in healthy pregnancy

Problem: The Th1/Th2 paradigm has recently been reconstituted to include a third population, Th17 cells. It has been reported that Th2 type immunity is predominantly present in normal pregnancy. However, the level of Th17 cells during pregnancy is still unclear. We investigated the level of peripheral Th17 cells in healthy pregnancy subjects. Method of study: To evaluate the levels of Th17 cells, we investigated the proportion of peripheral blood mononuclear cells that produced IL-17 in the first, second, and third trimester pregnancy subjects using flow cytometry. We further studied the proportion of decidual lymphocytes that produced IL-17 in early pregnant subjects. Results: Most of the IL-17-producing cells were CD4⁺ T cells. The number of circulating Th17 cells did not change during pregnancy. In a paired t-test of early normal pregnant subjects, the proportion of IL-17⁺ decidual lymphocytes was significantly higher than that of peripheral blood lymphocytes. Conclusion: Th17 levels in peripheral blood lymphocytes do not change during normal pregnancy.