POSTER CESSION 2: PREECLAMPSIA AND INFECTION- IMPACT OF ENVIRONMENT ON PREGNANCY- MALE INFERTILITY (Day-2)31th of MARCH 15:15-16-15POSTER CESSION 1: MATERNOFETAL TOLERANCE - RECURRENT MISCARRIAGES AND ENVIRONMENT- PERSONALIZED REPRODUCTIVE MEDICINE (DAY-1)30th of MARCH-15:00-16:00Day-1 Materno-fetal Tolerance and maternofetal dialoguePOSTER 1Studies of shifts in natural killer cell subpopulations under influence of trophoblast-derived choriocarcinoma JEG-3 cells and interleukin-15

The immune regulation at the fetal-maternal interface is crucial for establishing a healthy pregnancy as the mother must tolerate the semi-allogeneic fetus, while simultaneously being alert to protect both the mother and the fetus from pathogens. An imbalance in the immune regulation might have an important role in unexplained early pregnancy disorders. The decidual natural killer (dNK) cells comprise about 50-90 % of the decidual lymphocytes in the first trimester. Decidual NK cells secrete cytokines, angiogenic factors and growth factors, and they may play a key role for the development of the placenta. The majority of the circulating peripheral NK cells are cytotoxic with a CD56dimCD16+ phenotype. In contrast, the majority of the dNK cells are CD56brightCD16-, and are less cytotoxic and upon balanced activation seem to secrete factors important for placentation. The cytokine interleukin-15 (IL-15) is also present in the decidualized endometrium of the uterus. In the present study, we investigated a possible shift from a peripheral CD56dimCD16+ NK cell phenotype towards the CD56brightCD16- decidual NK cell phenotype induced by trophoblast cells with the choriocarcinoma cell line JEG-3 as a model, or by IL-15, or by both. Peripheral blood mononuclear cells (PBMCs) were isolated from buffy coats from 15 healthy, non-pregnant women n (<40 years). The PBMCs were incubated in co-cultures together with a monolayer of the human trophoblast-derived choriocarcinoma cell line JEG-3 with or without IL-15 for six days. Natural killer cell subpopulations in the PBMCs were analyzed by flow cytometry for the markers CD3, CD14, CD20, CD56, CD16 at day 0 and day 6. Natural killer cells were sub-grouped according to the expression of CD56 and CD16,and analyzed for surface expression of various receptors at day 0 and day 6. JEG-3 cells were analyzed by flow cytometry for the expression of human leukocyte antigens (HLA) (HLA-C, HLA-E, HLA-F and HLA-G). PBMCs co-cultured with IL-15 with or without JEG-3 for six days resulted in an increase in the CD56brightCD16- NK cell subpopulation and a reduction in the CD56dimCD16+ NK cell subpopulation. Interleukin-15 and the JEG-3 cells seemed to some degree to have an additive effect. Additionally, we observed an increase in the KIR2DL4 and ILT2 receptors on the CD56brightCD16- NK cell subpopulation after co-culture with IL-15 and JEG-3 cells. Our main findings were an increase in the CD56brightCD16- NK cell subpopulation after co-cultures with PBMCs and the trophoblast-derived choriocarcinoma cell line JEG-3 and addition of IL-15. The effect was primarily driven by IL-15. The results may indicate that the cytokine IL-15 and trophoblast cells at the fetalmaternal interface induce an increase in the CD56brightCD16- NK cell subpopulation of importance for fetalmaternal immune interactions and placentation