ABSTRACT
CD56dim cells, potent mediators of natural cytotoxicity, have direct contact with chorionic villi at the intervillous space. The manner the developing fetus evades NK cytotoxicity from these cells may determine the pregnancy outcome. CD69 is one of the earliest cell surface activation markers expressed by NK cells. In vitro models demonstrated that activated CD69+ NK cells are capable of lysing trophoblasts. This study aimed to investigate the relation between the percentage of these NK cells in peripheral blood and infertility. The study included two groups, each of 30 women, one with previous implantation failure and a fertile matching control group. CD3-CD56+dim and CD3-CD56+dimCD69+ NK were analyzed by flow cytometry. A higher percentage of CD3-CD56+dim and CD3-CD56+dimCD69+ in the study group than the control group was observed (P=0.0001 and P=0.003, respectively). Fair predictive values were evidenced by ROC curve analysis. We conclude that increase in CD56+dim NK and CD56+dim CD69+ NK cell percentages may be related to infertility problems.