Phenotypic features of low-density granulocytes in physiological pregnancy

During physiological pregnancy, the number of low-density neutrophils in the peripheral blood increases, but their phenotypic and functional features have not been practically studied. Therefore, the aim of this work is to study the expression of molecules characterizing cytotoxicity (CD16, CD107a), glucose transport (GLUT-l) and the state of mitochondria (by the inclusion of the MitoSpyGreen FM dye) by low-density granulocytes and in the general pool of granulocytes during physiologically proceeding pregnancy. The object of the study was the peripheral blood of conditionally healthy women in the first and third trimesters of physiological pregnancy. The comparison group consisted of conditionally healthy non-pregnant women in the follicular phase of the menstrual cycle. Low-density granulocytes were analyzed as a percentage of CD3-CD16+ cells in mononuclear leukocytes isolated on a ficolla-urographin density gradient (1.077 g/ml). The total granulocyte pool was studied as the percentage of CD3-CD16+ cells in the gate of peripheral blood granulocytes after removal of erythrocytes. Among granulocytes, subpopulations with high CD16 (CD16hl) and reduced CD16mt expression were isolated. It was found that in non-pregnant women CD16hi granulocytes dominate both in the general pool and among low-density granulocytes. During pregnancy, the number of low-density granulocytes increases and CD16int granulocytes become the dominant subpopulation both in the general pool of granulocytes and among low-density granulocytes. In non-pregnant and pregnant women in the first trimester, CD16hi- and CD16mt-granulocytes of low density and total pool are comparable in expression of GLUT-1, CD 107a, mass and volume of mitochondria. In the third trimester, CD107a expression on low-density CD16int granulocytes and in the general pool decreases compared to non-pregnant ones, and the mass and volume of mitochondria increase in both CD16hi and CD16mt granulocytes of the general pool only compared to the first trimester. The results obtained expand our understanding of the mechanisms regulating granulocyte functions during physiological pregnancy.