Background & Aim: Preeclampsia (PE) is the most common hypertensive disorder after 20 weeks of gestation, and its complications are the leading cause of maternal and fetal mortalities. Changes in the innate and adaptive immune systems play a crucial role in the pathogenesis of PE. Natural Killer Cells (NKTs) are the most abundant leukocytes during pregnancy, recruited and activated by ovarian hormones in the decidua. Recent evidence supports the idea that NKT cells exist in various environmental tissues and the decidua with their unique transcriptional profiles and cytokines, and bridge between innate and adaptive immune systems. Therefore, this study aimed to review the number, phenotype, changes, and functional function of NKT cells in normal pregnancy and preeclampsia. Materials & Methods: This study was a narrative review that utilized the PubMed-Medline and Embase databases to search for the role of NKT cells in pregnancy and preeclampsia. Data were obtained from searching and extracting relevant articles. Findings: The results of various studies showed that the number of NKT cells increases in preeclampsia compared to normal pregnancy. However, there isn't any significant difference in the quantity and characteristics of iNKT cells between normal pregnancy and preeclampsia. Nonetheless, normal pregnant women exhibit a slight but meaningful reduction in the secretion of IFN-γ from iNKT cells compared to women with preeclampsia. Discussion and Conclusion: NKT cells regulate the balance of Th1 and Th2 responses by secreting interleukin-4 and interferon-γ. During pregnancy, maternal immunity is biased towards the production of type 2 cytokines to inhibit the function of type 1 cytokines, which can be harmful to the developing fetus. This shift to type 2 cytokines occurs in normal pregnancy.

Background & Aims: Recent evidences indicate that parts of the immunoregulation system such as CD4+CD25+Tcells (Treg) and Th2 cells and Th1 cells, play very important roles in the maintenance of pregnancy. The deficiency in proper recognition of fetal alloantigen by the maternal immune system is associated with recurrent pregnancy failure. Here, we investigate the proportional changes of CD4+CD25+Tcells in peripheral blood of women with unexplained recurrent spontaneous abortion in comparison to women with normal pregnancy by using flowcytometry.Methods: The case group was comprised of 24 women who had at least three successive miscarriages with unexplained etiology. They had normal karyotypes, anticardiolipin and prolactin and their husbands had normal spermograms. The percentages of TCD4+CD25+cells in peripheral blood of these patients were compared with those of 21 women who had normal pregnancy with no history of pregnancy loss. Anti-CD4, anti-CD25 and anti-CD3 antibodies were added to lymphocytes isolated from peripheral blood. Then samples were incubated, centrifuged and washed. Finally cells were analyzed using FACS Caliber system and data of the two groups were compared.  Results: Mean percentage of CD4+CD25+bright T cells in peripheral blood in case group was significantly lower compared to the control group (P=0.000). Mean percentage of CD4-CD25 bright cells in the CD4+Tcell peripheral blood was significantly higher in case group campared to the control group (P=0.021). Conclusion: Decrease of CD4+CD25 bright T cells plays a major role in tolerating conceptus antigens and cytokine and might contribute to the maintenance of pregnancy. Inadequate CD4+CD25+Tcells or their functional deficiency may link with miscarriage. Therefore, alteration of CD4+CD25+T cells can be used as an immunologic marker for monitoring of patients with unexplained recurrent spontaneous abortion.

Background: Rheumatoid arthritis (RA) is defines as a Th1 dominant disease. Tregs cell are a rather new group of T cells that regulates other immune cells including Th1 and Th2. Foxp3 is a lineagedetermining factor for Treg cells. Several subsets of Foxp3+regulatory T cells are ever identified. In this study we investigated the frequency of CD4+Foxp3+Treg and CD8+Foxp3+Treg cells in patients with rheumatoid arthritis.Methods: Peripheral blood samples were obtained from 31 patients with rheumatoid arthritis and 21 healthy controls. Monoclonal antibodies including anti-CD4 and anti-CD8 and anti-Foxp3 were used and the staining process was performed. Flow cytometry were applied to evaluate the markers.Findings: The percentage of CD4+Foxp3+Treg cells was 1.03% ± 0.28 % in rheumatoid arthritis and 1.25% ± 0.3% in control group (P=0.010). The percentage of CD8+Foxp3+Treg cells was 0.79 ± 0.18, and 0.63 ± 0.16 in rheumatoid arthritis and control groups respectively (P=0.002). The WBC and Lymphocytes population in rheumatoid arthritis group were higher than control group (P=0.001).Conclusion: These data demonstrate that frequency of Treg cells might be involved in the pathogenesis of rheumatoid arthritis. This may be a contributory factor in the susceptibility to rheumatoid arthritis (Th1 dominant), or it may achieved during the progression of the disease.

Background: Polycystic ovary syndrome (PCOS) is considered as the most common cause of female infertility that affects 4-10% of women in the reproductive age. Previous studies have shown the role of a balanced immune response in a successful pregnancy and fertility. Objective: To investigate the T helper cells type 1 (Th1) /Th2/Th17/Treg paradigms in peripheral blood of infertile PCOS compared with normal fertile women. Methods: Peripheral blood mononuclear cells (PBMCs) were isolated at the late follicular phase from 10 PCOS and 10 fertile women. PBMCs were stimulated with PMA and ionomycin in the presence of Berefeldin A as Golgi stop agent to detect intracellular cytokine production (IFN-γ , IL-17, and IL-4) from CD3+CD4+T cells population indicating T helper (Th) cells subsets by flowcytometry. Moreover, regulatory T cells were enumerated using CD25 and Foxp3 markers. Results: In this study, we report that the frequency of Th1 cells was increased compared to Th2 cells in infertile PCOS when considering Th1/Th2 ratio (P=0. 05). Analysis of Th17/Th2 ratio showed a significant difference with a bias toward Th17 dominancy in PCOS (P=0. 02). The proportion of CD4+CD25+Foxp3+ regulatory T cells was significantly lower in PCOS patients than that of healthy fertile women (P=0. 02). Conclusion: In summary, Th1 and Th17 bias and reduction of Treg and Th2 cells as regulators of immune responses might be involved in the pathogenesis of PCOS. These results are suggestive of an altered immune response to inflammatory status in PCOS patients, likely causing some complications such as infertility in these patients.