751 0007-4888/14/1576-0751 © 2014 Springer Science+Business Media New York Detection of Microparticles of Leukocytic Origin in the Peripheral Blood in Normal Pregnancy and Preeclampsia V. A. Mikhailova, O. M. Ovchinnikova, M. S. Zainulina, D. I. Sokolov, and S. A. Sel’kov Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 157, No. 6, pp. 721-727, June, 2014 Original article submitted February 10, 2012 Microparticles are microvesicles forming during cell activation and as a result of apoptotic cell death. Normal pregnancy is associated with apoptosis induction in active immune sys- tem cells, present in the decidual tissue. Preeclampsia is associated with activation of the peripheral blood leukocytes and more intense apoptosis of the trophoblast cells. As a result, the number of microparticles in the peripheral blood is changing in normal gestation and in preeclampsia. The content of the leukocytic microparticles in the peripheral blood is evaluated in normal pregnancy and preeclampsia. The content of neutrophilic and monocytic micropar- ticles is higher than normally in preeclampsia, this indicating activation of these cells. The number of microparticles formed by NK cells is low in preeclampsia, which can reflect the incompetence of immunological tolerance mechanisms under these conditions. Key Words: leukocytes; microparticles; pregnancy; preeclampsia Laboratory of Immunology, D. O. Ott Research Institute of Obstetrics and Gynecology, North-Western Division of the Russian Academy of Medical Sciences, St. Petersburg, Russia. Address for correspon- dence: corbie@hotmail.ru. D. I. Sokolov All eukaryotic cells form small vesicles of 0.1-1 μ in size as a result of apoptosis; these vesicles are of- ten called microparticles. Microparticles form also during cell activation and cell–cell interactions [10]. The microparticles form also in health, as a result of cell–cell communications [10]. Normal pregnancy is associated with induction of apoptosis in active T cells and cytotoxic NK cells in the decidual and placental tissue. Preeclampsia is associated with the peripheral blood leukocyte activation in the uteroplacental circu- lation [11] and migration of various leukocyte types to the decidual tissue [6]. In addition, preeclampsia is characterized by induction of the trophoblast cell death by the decidual tissue NK cells and cytotoxic T cells [1], activation of placental and decidual macro- phages and their secretion of proinflammatory cyto- kines. These processes in the uteroplacental contact zone may result in the formation of microparticles. Microparticles are present in the peripheral blood in normal pregnancy and in preeclampsia [2]. The func- tional characteristics of the microparticles circulat- ing in the peripheral blood in normal gestation and preeclampsia presumably differ. In normal pregnancy, the microparticles are potentially capable of induc- ing complement cascade reactions. In preeclampsia, the peripheral blood contains higher levels of mic- roparticles forming complexes with C-reactive protein [2]. At present, attempts are made at distinguishing the microparticles by their origin by phenotyping. In normal pregnancy, the syncytiotrophoblast micropar- ticles are present in the peripheral blood, their content increasing in preeclampsia. The functional characte- ristics of microparticles with different phenotypical characteristics differ. For example, microparticles of T-lymphocytic origin inhibit endothelial NO synthase expression by endothelial cells in vitro. Published data on the content of microparticles in the peripheral blood Bulletin of Experimental Biology and Medicine, Vol. 157, No. 6, October, 2014 MICROBIOLOGY AND IMMUNOLOGY DOI 10.1007/s10517-014-2659-x