Decidual CD56+ Natural Killer Cells in Spontaneous Early Pregnancy Loss- An Immunohistochemical Study

Changes in expression of Ki-67, CD16 and CD56 by natural killer cells from peripheral blood mononuclear cells in the setting of recurrent miscarriage after in vitro culturing in the presence of trophoblast cells and IL-2

The aim of this research was to assess the proliferative activity of Natural Killer Cells (NK cells) from Peripheral Blood Mononuclear Cells (PBMCs) in the presence of trophoblast cells in women with a history of recurrent miscarriages. We examined the peripheral blood of women with recurrent miscarriage in the proliferative (n = 12) or secretory (n = 13) phase of their menstrual cycle, and pregnant women with a history of recurrent miscarriage at 6-7 weeks of their current pregnancy (n = 14). Controls were fertile non-pregnant women in the proliferative (n = 11) or secretory (n = 13) phase of their menstrual cycle, and pregnant women at 6-7 weeks of a physiologically normal pregnancy (n = 20). We used IL-2 as a factor maintaining PBMCs viability during long-term culturing. We established that culturing in the presence of IL-2 contributed to an increase in the number of CD56+CD16- NK cells and to a decrease in the number of CD56+CD16+ NK cells from PBMCs compared with these numbers before culturing in both healthy women and in women with recurrent miscarriage. After culturing of PBMCs in the presence of trophoblast cells and IL-2 (compared with culturing without trophoblast cells), the intensity of Ki-67 expression by NK cells was reduced in the whole NK cell population (CD3-CD56+), and in the CD56+CD16- and CD56+CD16+ populations of NK cells in women with recurrent miscarriage and in healthy controls. The intensity of CD56 expression was reduced in the presence of trophoblast cells and IL-2 in non-pregnant women with recurrent miscarriage in the secretory versus the proliferative phase of the menstrual cycle.