Study on the Relationship Between Th17 Cells and Unexplained Recurrent Spontaneous Abortion

Problem What is the relationship between Th17 cells and unexplained recurrent spontaneous abortion (URSA)? Method of study CD4+ interleukin (IL)-17A+ T (Th17) cells and CD4+ CD25brightFoxp3+ regulatory T (Treg) cells in peripheral blood were analyzed by flow cytometry; IL-17 concentrations in cell culture supernatants were quantitatively determined by enzyme-linked immunosorbent assay; and IL-17A positive cells in decidua tissues were measured by immunohistochemistry. Results The proportion of Th17 cells and IL-17A concentrations was both significantly higher in patients with URSA than in normal early pregnant (NEP) and non-pregnant (NP) patients, Treg frequencies were significantly lower in patients with URSA than in NEP patients, and the ratio of Th17 to Treg was significantly higher in the URSA group than in the other two. Additionally, the percentage of IL-17A cells in deciduas was significantly higher in patients with URSA than in NEP patients. Conclusions Human Th17 cells may play a major role in rejecting conceptus antigens and therefore may be harmful to the maintenance of pregnancy. The data also suggest that Treg cells are beneficial to pregnancy. There may exist a balance of Th17/Treg in normal pregnancy.