Altered distribution of NK and NKT cells in follicular fluid is associated with IVF outcome

The aim of this study was to investigate differences in the relative distributions of subsets of natural killer (NK) cells, including immunoregulatory NK cells (CD56+CD16−), cytotoxic NK cells (CD56+CD16+), as well as total NK cells (CD56+CD3−), and NKT cells (CD56+CD3+) in peripheral blood and follicular fluid in subjects with successful or unsuccessful IVF treatment. The immunoregulatory NK cell population in follicular fluid of women who failed to achieve pregnancy after IVF treatment was significantly decreased compared to women who became pregnant after IVF. Conversely, the NKT cell population in the follicular fluid of women with unsuccessful treatment was significantly elevated compared with those with successful IVF. Understanding the changes in the distribution of NK and NKT cell populations in follicular fluid might serve as the basis for a more detailed study to determine whether NK cell parameters have prognostic value in guiding the selection of individual ova for use in IVF procedures.