Number of decidual natural killer cells & macrophages in pre-eclampsia

Background & objectives: The process of human placentation is complex and still not well understood. This study was aimed to examine the relationship between clinical features of pre-eclampsia and degree of trophoblastic invasion after its immunohistochemical visualization in the context of possible alterations in the number of natural killer (NK) cells and macrophages in the decidua. Methods: This prospective study included a study group comprising 30 pregnant women with preeclampsia delivered by caesarean section and a control group comprising 20 healthy pregnant women also delivered by caesarean section. Samples of placental bed obtained during caesarean section were analyzed after immunohistochemical labelling CD56(+) NK cells, CD68(+) macrophages and cytokeratin 7 trophoblastic cells. Results: In pre-eclampsia, there was a significantly lower number of CD56(+) NK cells in the decidua (P<0.001) and a higher number of CD68(+) macrophages (P<0.001) compared to control group. In the subgroup of pre-eclampsia with intrauterine growth retardation (IUGR), a significantly greater number of NK cells (P<0.05) was recorded, as well as an increased number of macrophages, but not significantly compared to pre-eclampsia without IUGR. There was no significant difference in the distribution of these cells in the decidua in relation to the severity of pre-eclampsia. CD56(+) NK cells were significantly less (P<0.05) and macrophages were more (P<0.05) in the group with poor trophoblastic invasion. Interpretation & conclusions: Alterations in the number of immune cells in relation to the degree of trophoblastic invasion indicated their role in aetiopathogenesis of pre-eclampsia, while the direct association between their number and severity of pre-eclampsia was not confirmed.