Analysis of cytotoxic activity of peripheral blood natural killer cells in women with recurrent miscarriage

Around 50% of recurrent spontaneous abortions (RSA) remain unexplained. Immunological etiology has been proposed, supported by evidence of lower count of natural killer (NK) cells in peripheral blood of RSA women compared to women with normal delivery history. However, studies concerning the cytotoxic activity of NK cells in women with RSA are still controversial. We performed an observational case-control study assaying peripheral blood NK (pNK) cells cytotoxic activity in non-pregnant RSA women compared to non-pregnant women with normal delivery history. Twelve RSA and nine control women were recruited and blood samples were drawn during the luteal phase of ovarian cycle. pNK cells were incubated with target CFSE-labeled K562 cells and cytotoxicity was measured by cytofluorimetry. In non-pregnant RSA women pNK cytotoxic activity was not significantly altered compared to control women. In luteal phase of ovarian cycle the level of cytotoxic activity of pNK cells is not a marker for predicting RSA, and clinicians should not use pNK activity as a systematic recurrent pregnancy loss examination.