[ACTIVATION OF PERIPHERAL NATURAL KILLER CELLS IN WOMEN WITH REPEATED EARLY PREGNANCY LOSS]

The increased number of peripheral blood NK (pNK) cells has been discussed as a factor for embryo implantation failure and early pregnancy loss. However, the assessment of activated pNK cells with increased cytotoxic activity could be a distinct marker for immune dysregulation leading to pregnancy complications. CD69 membrane receptor expression has been measured by flow cytometry in different subtypes of pNK cells in 55 women with two or more pregnancy loss between six and twelve week of gestation with absence of any hormonal, anatomical or inherited cause for pregnancy loss and in 43 healthy women with at least one delivery at term and no history for reproductive failure. Increased expression of CD69 in CD56 positive pNK cells was found in the study group compared to controls (12.2% versus 6.5%, p<0.005). In addition, the subpopulation of CD56dim and CD56brightpNK cells in women with recurrent pregnancy loss showed increased percent of CD69 activation marker expression compared to controls (respectively 13.2% versus 7.2 p<0.005; and 4.6% versus 3.1% p=0.04). CD56brightCD16negative pNK cells (identical with those in uterine endometrium) in the investigated group has been found with higher CD69 expression compared to controls (3.3% versus 1.7%, p=0.03). Primary dysregulation in NK cells activity could be supposed in women with repeated early pregnancy loss without another underlined pathology. Investigation of active status of NK cells but not only NK cell count could be evaluation marker of impaired immunology regulation in early pregnancy development.