Comparative analysis of NK cell subsets in menstrual and peripheral blood of patients with unexplained recurrent spontaneous abortion and fertile subjects

Natural killer (NK) cells play a fundamental role in maintaining pregnancy. Based on the availability and non-invasive method of collection of menstrual blood (MB), here we investigated for the first time a comparative analysis of NK cell subsets in MB and peripheral blood (PB) of women with recurrent spontaneous abortion (RSA) and fertile women. PB and MB of healthy fertile (n = 15) and RSA women (n = 15) were sampled simultaneously on the second day of the menstrual cycle. Proportions of CD56+CD3−CD16+/−, CD56+CD3−CCR7+/−, and CD56+CD3−CD45RO+/− cells were analyzed using flow cytometry. In the MB of both groups, proportions of CD16+ and CD45RO− NK cells were significantly lower than in the PB. In parallel, CD56+CD16+CCR7− and CCR7+ cells were present in significantly smaller amounts in MB than in PB. However, the amounts of CD56+CD16−CCR7− and CCR7+ cells were greater in MB. In comparison to the fertile group, the percentage of MB CD45RO+ NK cells was significantly lower and frequencies of PB CD16−, CD45RO− and CD56+CD16+CCR7+ subsets were significantly higher in RSA patients. Different subsets of NK cells are differentially distributed in MB in comparison with PB in women with RSA and fertile subjects. Population differences of NK cell subsets in RSA patients and normal controls were more clearly reflected at the systemic level.