Distribution of Th1 and Th2 cell populations in human peripheral and decidual T cells from normal and anembryonic pregnancies

Objective: To examine whether maternal immune responses during normal pregnancy are Th2 biased and whether there are specific changes when anembryonic pregnancy occurs. Design: Prospective study. Setting: Department of Obstetrics and Gynecology at a university hospital. Patient(s): We studied 32 pregnant women receiving elective abortions of normal pregnancies and 35 women with anembryonic pregnancies between 6 weeks and 10 weeks of gestational age. Intervention(s): Using the multilabeling capability of three-color flow cytometry, it is possible to measure intracellular cytokines and cell surface markers simultaneously to determine which cells are the cytokine-producing cells. Main Outcome Measure(s): We examined the extent and proportion of mononuclear cells expressing specific T-cell surface markers and cytokines, interferon γ, and interleukin 4 in the peripheral blood and deciduae. Secreted cytokines in the supernatants after 24-hour culture were also compared. Result(s): During the unstimulated status, the proportion of IL-4-secreting cells significantly exceeded that of IFN-γ-secreting cells in the peripheral blood and decidua in normal pregnancies and was significantly decreased when anembryonic pregnancies occurred. Consequently, the Th1/Th2 ratios were increased during anembryonic pregnancies. However, after 24-hour culture, only another Th2-type cytokine, IL-10, was markedly increased and exceeded IFN-γ secretion in cultures from both the peripheral blood and decidua in normal pregnancies. Conclusion(s): The decidual T lymphocytes are Th2 predominant. When anembryonic pregnancy occurs, this Th2 predominance disappears.