Diagnostic value of preactivated neutrophils in preeclampsia

Objective. To investigate the relationship of the levels of preactivated (primed) neutrophils in the peripheral blood of pregnant women with preeclampsia. Subjects and methods. The investigation enrolled 14 women with preeclampsia (a study group, Group 1), 15 women with physiological pregnancy (a control group, Group 2), and 11 non-pregnant women (to obtain normative values). Formyl peptide, Ficoll-Hypaque (1.077 and 1.119 g/ml) gradients, lucigenin, Roswell Park Memorial Institute (RPMI) 1640medium, Hanks medium, and fetal calf serum (Sigma-Aldrich) were determined in the peripheral blood. Neutrophils were isolated from the blood samples obtained from the ulnar vein (the anticoagulant heparin 35 IU/ml) using a two-step Ficoll-Hypaque gradient. Red blood cells were destroyed by hypotonic lysis. Neutrophils in the suspensions were at least 96%. The live cells tested with trypan blue were 94%. Suspensions containing 1^106 cells/ml were prepared. Formyl-methionyl-leucyl-phenylalanine (fMLP, 2 pM) was used as a stimulant. The formation of oxygen radicals was recorded in imp/sec, by using the luminophor lucigenin (30 pM) on a Biotox-7 chemiluminometer (Russia). The maximum radical formation amplitude, the time of its achievement, and the light sum were determined for a fixed time period. Results. The cell suspensions from non-pregnant women showed a monotonic spontaneous increase in oxygen radical formation at a very low rate. The rate increased by 1.3 times in healthy pregnant women (p > 0.05). The rate of spontaneous oxygen radical generation rose sharply in pregnant women with preeclampsia. In this group, the formation of oxygen radicals reached maximum values and plateaued at 24±7 min. The spontaneous radical formation might be due to the stimulation of initially primed neutrophils as a result of their adhesion on the cell walls. To test this assumption, the standard stimulant fMLP that strongly stimulates the neutrophil generation of oxygen radicals were added to the suspensions from the women with preeclampsia. It should be noted that in both non-pregnant women and healthy pregnant women, fMLP significantly increased the level of radicals compared to the responses of neutrophils in women with preeclampsia. Conclusion. The potentiated response to formyl peptide due to spontaneous neutrophil stimulation in pregnant women with preeclampsia suggests that their peripheral blood contain primed cells. This total response may suggest that the mechanism of stimulation of neutrophils due to their adhesion on the cell wall and to fMLP stimulation is different, additive in nature, and is carried out by different processes

preeclampsia, oxidative stress, preactivated neutrophils, priming