Association of recurrent implantation failure and recurrent pregnancy loss with peripheral blood natural killer cells and interferon-gamma level

Objective Fetal uterine survival depends on maintaining an immune balance between the mother and fetus. This study aimed to investigate the correlation of blood peripheral natural killer (NK) cells and interferon-gamma (IFN-gamma) with recurrent recurrent implantation failure (RIF) and recurrent pregnancy loss (RPL). Methods In this case-control study, peripheral blood samples were obtained from three groups of RPL, RIF, and parous women without a history of abortion or infertility problems and analyzed by lymphocyte-based flow cytometry. Afterward, the levels of NK cells and IFN-gamma were determined. All data were analyzed using one-way analysis of variance and non parametric Kruskal-Wallis tests. Results The level of IFN-gamma in the RPL group was significantly higher than that in parous women and the RIF group (P<0.05), whereas its level in the RIF group was not significantly different from the control group (P>0.05). A significant correlation was found between the levels of IFN-gamma and NK cells in the RPL group (r=0.481; P=0.02). However, no significant correlation was found between the levels of IFN-gamma and the active NK cells in the RPL group (P=0.08). Moreover, no significant correlation was found between the levels of NK cells (whether activated or not) and IFN-gamma in the RIF patients (P>0.05). Conclusion Immune dysfunction may not be involved in implantation failure during IVF but may be involved in recurrent miscarriage, probably by increasing IFN-gamma levels.