Cytokine secretion by NK cells is abnormal in some women with recurrent pregnancy loss (RPL). Cytokine production is usually evaluated after stimulation with PMA and ionomycin. However, stimulation of uterine NK cells with semen corresponds more closely to physiological conditions at the time of conception. As seminal plasma has immunomodulatory properties, we aimed to elucidate compatibility between uterine NK cells and semen. Endometrial samples were stimulated with PMA/ionomycin, semen, seminal plasma, or spermatozoa. Thereafter, cytokine production by NK (CD56^bright) cells was evaluated using flow cytometry and compared between women with and without a history of RPL associated with abnormal NK cell distribution in the endometrium or unexplained RPL. The ratios (%) of NK cells producing IFN-γ and TNF-α (NK1 phenotype), IL-4 (NK1/NK2 phenotype), and IL-10 (NK1/NKr1 phenotype) were significantly lower after stimulation with semen than with PMA/ionomycin (P < 0.01). After exposure to semen, ratios (%) of NK cells producing IL-4 and IL-10 in patients with unexplained RPL were significantly lower (P < 0.05), whereas those of NK1/NK2 and NK1/NKr1 were significantly higher (P < 0.01) than those in controls. The shift of endometrial NK cells to the NK2 phenotype was more pronounced when stimulated by semen than by PMA/ionomycin. However, a semen-induced shift to NK1 in women with unexplained RPL could induce miscarriage. Couple-specific immunological compatibility tests through semen stimulation in vitro might provide important information to avoid RPL.

在一些复发性流产 (RPL) 的女性中，NK 细胞的细胞因子分泌异常。通常在用 PMA 和离子霉素刺激后评估细胞因子的产生。然而，用精液刺激子宫 NK 细胞更符合受孕时的生理条件。由于精浆具有免疫调节特性，我们旨在阐明子宫 NK 细胞和精液之间的相容性。用 PMA/离子霉素、精液、精浆或精子刺激子宫内膜样品。此后，NK 产生细胞因子（CD56^亮) 细胞使用流式细胞术进行评估，并在有和没有与子宫内膜中异常 NK 细胞分布或原因不明的 RPL 相关的 RPL 病史的女性之间进行比较。用精液刺激后产生 IFN-γ 和 TNF-α（NK1 表型）、IL-4（NK1/NK2 表型）和 IL-10（NK1/NKr1 表型）的 NK 细胞的比率（%）显着低于PMA/离子霉素 ( P < 0.01)。暴露于精液后，不明原因 RPL 患者 NK 细胞产生 IL-4 和 IL-10 的比例（%）显着降低（P < 0.05），而 NK1/NK2 和 NK1/NKr1 的比例（%）显着升高（P< 0.01) 比对照。与 PMA/离子霉素相比，在精液刺激下，子宫内膜 NK 细胞向 NK2 表型的转变更为明显。然而，在不明原因的 RPL 女性中，精液诱导的 NK1 转移可能会导致流产。通过体外精液刺激进行的夫妻特异性免疫相容性测试可能会提供避免 RPL 的重要信息。