Possible role of natural killer and natural killer T-like cells in implantation failure after IVF.

During implantation, maternal immunoactivation and tolerance are not only limited to the decidua but are also observed in the periphery, predominantly affecting the innate immune system. Since unexplained female infertility, as well as recurrent spontaneous abortion and implantation failure, are thought to be associated with pathological maternal immunotolerance mechanisms, this study focused on immune profile analysis of IVF candidates. Previous studies on peripheral natural killer (NK) cell characteristics of IVF patients have been limited to the comparison of blood samples taken prior to the IVF procedure. This study performed a follow-up study and compared patient's data obtained on the day of oocyte collection with the data 1 week after embryo transfer. The aim was to investigate phenotypic (subpopulations, CD69, T-cell immunoglobulin mucin 3 and NK-activating receptor expression) and functional (perforin and CD107a expression) changes in the peripheral NK and NK T (NKT)-like cell populations. During this short period of time around the IVF procedure, women with failed IVF reflected unfavourable Th1-oriented changes of NK and NKT-like cells. In comparison the follow-up data for women with successful conception remained principally constant. The observed peripheral changes during early pregnancy in the same individual may also have importance in successful embryo implantation.