Characterization of NKT cells in human peripheral blood and decidual lymphocytes

Problem: To examine whether natural killer (NKT) cells are present in human pregnancy decidua. Method of study: We calculated the percentage of CD3⁺CD161⁺Vα 24⁺-NKT cells in peripheral blood and early pregnancy decidua, and analyzed intracellular cytokines, interleukin (IL)-4 and interferon (IFN)γ in NKT cells using flow cytometry. Results: A distinct subset of CD3⁺CD161⁺ lymphocytes expressing an invariant antigen receptor encoded by the Vα24 and Vβ11 segment was accumulated in the decidua. In pregnant subjects the percentages of NKT cells were significantly increased in the decidua compared with peripheral blood. Both NKT cells in the decidua and the peripheral blood had an ability to rapidly produce cytokine associated with Th1 (IFNγ) and Th2 (IL-4). Interestingly, the percentages of IL-4 and IFNγ producing NKT cells were significantly higher in the decidua compared with the peripheral blood. Conclusions: These findings suggest that NKT cells might control the Th1/Th2 balance by producing IL-4 and IFNγ at the feto-maternal interface.