Neonatal platelet activation in preeclampsia.

Preeclampsia is associated with an increased platelet activation; however, there are few studies concerning platelet activation of the newborn. The aim of our study was to compare platelet activation in newborns of preeclamptic mothers to newborns of healthy mothers by using whole blood flow cytometry. Blood samples were obtained from 20 newborns (10 healthy controls, 10 cases of preeclampsia/HELLP [hemolysis, elevated liver enzymes, and low platelet count] syndrome) during cesarean section. Antibodies against the following antigens were used as markers for platelet activation: CD 41, CD62P, CD 63, and platelet-bound fibrinogen. In addition to the basal platelet activation, the ability of platelets to undergo activation as a result of in vitro incubation with a weak agonist (adenosine diphosphate) was evaluated. A significant difference between the groups concerning basal platelet activation could only be seen for platelet-bound fibrinogen; the control group showed a higher extent of platelet activation (16.6 +/- 11.3 vs. 6.1 +/- 4.9; p = 0.03). Incubation with adenosine diphosphate in the control group resulted in minor increases of platelet activation, which was significant only for platelet-bound fibrinogen (16.6 +/- 11.3 vs. 42.5 +/- 22.1; p = 0.02). However, the preeclamptic group showed significantly increased levels of platelet activation for all used markers after in vitro activation (CD 41: 115.6 +/- 18.2 vs. 163.2 +/- 29.6; p = 0.002; CD62P: 2.4 +/- 0.4 vs. 3.9 +/- 0.3; p < 0.001; CD 63: 2.7 +/- 0.5 vs. 3.7 +/- 0.6; p = 0.002; platelet-bound fibrinogen: 6.1 +/- 4.9 vs. 55.1 +/- 9.1; p < 0.001). Preeclampsia or HELLP syndrome is therefore associated with an increased susceptibility to neonatal platelets, even against weak activators such as adenosine diphosphate. Whether this results from peculiarities in the fetal vascular environment or maternal influences is yet uncertain.