摘要 : Embryo-secreted preimplantation factor (PIF) is necessary for, and its concentration correlates with, embryo development in humans by promoting implantation and trophoblast invasion. Synthetic PIF (sPIF) modulates systemic immunit... 展开 Embryo-secreted preimplantation factor (PIF) is necessary for, and its concentration correlates with, embryo development in humans by promoting implantation and trophoblast invasion. Synthetic PIF (sPIF) modulates systemic immunity and is effective in autoimmune disease models. sPIF binds monocytes and activated T and B cells, leading to immune tolerance without suppression. This study examined the effect of sPIF on natural killer (NK) cell cytotoxicity in 107 consecutive nonselected, nonpregnant patients with recurrent pregnancy loss (RPL) and 26 infertile IVF patients (controls). The effects of sPIF, intravenous gamma immunoglobulin (Ig), Intralipid and scrambled PIF (PIFscr; negative control) on NK cell cytotoxicity to peripheral-blood cells were compared by flow cytometry of labelled-K562 cell cytolysis. The effects of sPIF and PIFscr on whole-blood NKCD69+ expression were also compared. In patients with RPL, sPIF inhibited NK cell cytotoxicity at doses of 2.5 and 25 ng/ml (37% and 42%) compared with PIFscr (18%; P < 0.001), regardless of the proportion of peripheral-blood NKCD56+ cells to lymphocytes. Pre-incubation of blood from infertile patients with sPIF for 24 h decreased NKCD69+ expression versus incubatino with PIFscr (P < 0.05). In conclusion, sPIF inhibits NK cell cytotoxicity by reducing NKCD69 expression, suggesting a significant role in RPL patients. 收起