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Objectives: Thyroid autoimmunity is considered as the most prevalent autoimmune condition in women in fertility age. There are different clinical evidences indicating the association between thyroid autoimmunity and increased risk of RPL. This study aimed to analyze the association of Tregs and Th17 cells development factors and anti–thyroid peroxidase (anti-TPO) antibodies in RPL patients. Healthy controls (n = 36), TPO + controls (n = 25) and TPO + RPL (n = 32) participated in this study. After blood sampling, the frequency of Th17 and Tregs was evaluated using flow cytometry. Real-time PCR and ELISA was used to assess the status of Tregs and Th17 related transcription factors and cytokines in mRNA and protein level, respectively. Results: TPO + RPL group showed a higher Th17 frequency compared to healthy controls and TPO + controls groups (p = 0.0002 and p = 0.04, respectively). Additionally, mRNA expression levels of RORγT and IL-17 were significantly higher in TPO + RPL compared to healthy controls and TPO + controls groups. In contrast, Foxp3 and TGFβ expression was lower in TPO + RPL. ELISA findings also indicated a significantly higher IL-17 and lower TGFβ secretion in TPO + RPL compared to healthy controls and TPO + controls. Thyroid autoimmunity should intensely be controlled specially in patients with RPL history. [ABSTRACT FROM AUTHOR]

Pregnancy problems including recurrent pregnancy loss, repeated implantation failure and pre‐eclampsia are common problems in the reproductive ages. Different reasons such as genetic, immunological, and environmental agents and also infections could develop these complications. In those cases in which the cause of the abortion is diagnosed, the chance of a successful pregnancy is increased by eliminating defective factors. However, in patients with unknown causes, there may be an imbalance in immune cells pattern. As a matter of fact, an inappropriate immune response is often associated with a failed pregnancy. Hence, the focus of treatment is to increase tolerance, not to suppress maternal immune system. These findings are linked to an elevated number of Treg cells and immune checkpoints through normal pregnancy. The present review discusses the balance of myeloid‐derived suppressor cells, natural killer cells, T cells, and immune checkpoints, and also targeting them to maintain pregnancy and prevent associated complications. [ABSTRACT FROM AUTHOR]

Purpose: The authors developed nanostructured lipid carriers (NLCs) loaded with sirolimus (SRL) and cyclosporine (CsA) to improve their therapeutic efficacy in recurrent pregnancy loss (RPL) patients. Methods: Mono‐delivery and co‐delivery of SRL and CsA by NLCs (S‐NLCs, C‐NLCs, and S‐C‐NLCs) were developed. The MTT assay was used to study the optimum dose of formulations. PCR, Western blotting, and ELISA were also conducted. Results: Well‐designed nanodrugs with a suitable size, zeta potential, desirable encapsulation efficiency drug loading, and cellular uptake confirmed optimum formulations. Based on cell viability, the amounts of SRL and CsA could be reduced greatly due to the co‐delivery by NLCs. Following S‐NLCs and C‐NLCs interventions in T cells of patients with RPL and immune abnormality, a significant difference was observed in transcription factors and cytokine levels of Th1, Th17, and Tregs compared with healthy samples. Thus, a higher level of pro‐inflammatory cytokines (IFN‐γ, TNF‐α, IL‐17, and IL‐21) and their regulators (T‐bet and RORγt), as well as a lower level of an anti‐inflammatory cytokine (IL‐10) and its regulatory (Foxp3), were observed. However, no significant difference was found following the S‐C‐NLCs intervention. Conclusions: S‐C‐NLCs effectively balance the immune responses in peripheral T cells in RPL patients to induce maternal immune tolerance. [ABSTRACT FROM AUTHOR]

Recurrent pregnancy loss (RPL) is a one of the most common obstetrical complications. Since, the successful pregnancy occurs in T helper 2 (Th2)‐dominant situation and since, Th1 type immunity is related to pregnancy failure, we investigated the effects of cyclosporine on Th1 and Th2 cells in RPL women. Totally, 76 RPL patients (38 women as treated group and 38 as control group) were included in this study. Flow cytometry was utilized to analyze the frequency of Th1 and Th2 in blood samples. Also, real‐time polymerase chain reaction was carried out to assess the messenger RNA (mRNA) expression of transcription factors and enzyme‐linked immunosorbent assay was used to evaluate Th1 and Th2 related cytokines. Significant decrease in Th1 frequency (p = 0.0004), Th1/Th2 ratio (p < 0.0001), T‐bet mRNA expression (p < 0.0001), interferon‐γ (p = 0.0007), and tumor necrosis factor α (p = 0.0002) secretion level were observed in cyclosporine group. Moreover, significant increase in Th2 frequency (p < 0.0001), mRNA expression of GATA binding protein 3 (p = 0.0001), and interleukin 10 secretion level (p = 0.0027) was also evident in treated group. At the end of the investigation, 31 (81.5%) patients in cyclosporine‐treated group had successful childbirth when compared with 16 (42.1%) women in control group (p = 0.0001). Given this, cyclosporine treatment for RPL patients with elevated Th1/Th2 ratio can result in improved pregnancy outcome. [ABSTRACT FROM AUTHOR]

Background: Recurrent miscarriage (RM) has a multifactorial etiology mainly due to chromosomal abnormalities and immunological factors. Treating RM has remained to be a challenging issue and the role of intravenous immunoglobulin (IVIG) in treating RM is still controversial. Materials and Methods: This study aimed to evaluate the changes in natural killer (NK) cells' frequency and cytotoxicity in patients with RM who received the IVIG therapy. A total of 78 women with a history of three or more recurrent miscarriages were included and their peripheral blood was drawn in case of positive pregnancy test. On the same date, 400 mg/kg of IVIG was administrated intravenously in 38 women and it continued every four weeks through weeks 30–32 of gestation. The remaining 40 patients with RM were included to be the untreated control group. Then, the effects of IVIG on NK cell frequency, cytotoxic activity, and the expression of inhibitory and activating receptors in the patients with RM, pre and posttreatment were assessed. Results: NK cells percentage and cytotoxicity were significantly reduced in the IVIG‐treated patients after 32 weeks of gestation (p < 0.0001). Expression levels of inhibitory receptors was increased, however, the expression levels of activating receptors were significantly decreased after the IVIG therapy. Pregnancy outcome after the treatment was significantly higher (86.8%) in the IVIG‐treated patients than controls (45%; p = 0.0006). Conclusion: Our results suggested that women with RM may benefit from IVIG as a therapeutic approach and the frequency and functional status of peripheral NK cells may serve as a valuable predictive factor of therapy response. [ABSTRACT FROM AUTHOR]

Regulatory T (Treg) cells have been identified as key immune regulators and are important to fetal survival within the maternal uterus. T helper 17 (Th17) cells have also emerged as a new subset of effector helper T cells and play significant roles in host defense against extracellular pathogens, autoimmune conditions, and inflammatory chronic diseases. Recent findings have provided strong support for the contribution of Th17 and Treg cells to successful pregnancy. Disorders of pregnancy such as preeclampsia (PE) and recurrent spontaneous abortion (RSA) are associated with low frequencies of Treg cells and high levels of Th17 cells. Here, we review current knowledge on Tregs and Th17 cells and shed light on their roles in both normal pregnancy and PE. We also discuss the imbalance between Th17 cells and Treg cells which is known as a major contributory factor in the pathophysiology of PE. [ABSTRACT FROM AUTHOR]

• In order to establish an optimal immune environment, for the semi-allogenic foetus, the maternal immune system undergoes functional changes. • Immune checkpoints and microRNAs play a role in establishing the appropriate local immune environment for successful pregnancy. • Further studies of the expression and function of ICPs in RPL women migwill potentially provide new opportunities in therapy and diagnosis. Recurrent pregnancy loss (RPL) is a multifactorial disorder, associated with immunologic abnormalities. During pregnancy, the maternal immune system uses different tolerance mechanisms to deal with a semi-allogenic fetus. The expression of immune checkpoints and their related miRNAs in immune cells can ensure pregnancy at the feto-maternal interface by modulating immune responses. This study aims to evaluate the expression of the immune checkpoint molecules PD-1 and Tim-3 on circulating T cells by flow cytometry, that of mir-138 and mir-155 in PBMCs by Real-time PCR, and the concentrations of TGF-β and IP-10 in the sera of women suffering from RPL as well as of gestational age-matched healthy pregnant women by ELISA. The percentage of PD-1 or Tim-3 expressing CD8+ T cells was significantly lower in RPL patients compared to the controls, while there was no significant difference in Tim-3 expression of CD4+ T cells between the two groups. The mRNA of both the PD-1 and Tim-3 genes were downregulated in PBMCs of RPL patients compared to controls, however, the difference was not statistically significant for Tim-3. The concentration of TGF-β was significantly lower and that of IP-10 was significantly higher in the sera of RPL patients than in those of the controls. The relative expression of mir-138 and miR-155 were significantly lower, in PBMCs of RPL patients than in those of healthy pregnant women. These data confirm that by affecting cytokine production, immune checkpoints, and microRNAs play a role in establishing the appropriate local immune environment for successful pregnancy. The wider analysis of immune checkpoints may also yield new biomarkers for the diagnosis and prevention of RPL. [ABSTRACT FROM AUTHOR]

• Maternal-fetal immune dysregulation is one of the risk factors that increases the probability of reproductive failure. • Maternal tolerance toward fetal alloantigens is required to prevent this semi-allograft rejection. • Immunotherapy and cell therapy methods possess the ability to manage reproductive failures by controlling immune cells. Maternal-fetal immune dysregulation is one of the risk factors that increases the probability of embryo rejection and reproductive failure. The stimulation of immunological tolerance and suppression of immunological rejection are prerequisites for protecting embryos and preventing immunological attacks. Hence, it appears that immunomodulatory and immunosuppressive therapies can manage reproductive failures by controlling immune cells. The current medical literature has shown that immunotherapy approaches and cell therapy have promising results in improving pregnancy outcomes and live birth rates. These outcomes are obtained by regulating maternal immune responses, and exerting positive effects on human reproductive processes. [ABSTRACT FROM AUTHOR]

About 17% of couples suffer from infertility conditions, worldwide. The most common reasons for female infertility are ovulation disorders, fallopian-related disorders, RM, RIF, endometriosis, and unexplained infertility. Despite advances in Assisted Reproductive Technologies, infertility has remained a serious problem. In recent years, a considerable progress in cell therapy as an emerging approach for the treatment infertility has been made. Cell therapy involves utilizing lymphocytes, platelet -rich plasma, PBMCs and different types of stem cells as therapeutic agents. Stem cells are usually multipotent cells existed in embryos, fetuses, and adults that proliferate and differentiate into different cell types under certain circumstances. The main types of stem cells are embryonic stem cells, decidual stromal cells, MSCs, human amniotic epithelial cells, and induced pluripotent-stem cells each functioning in a different way. The advantages of using stem cells as therapeutic agents are convenient sampling, abundant sources, and avoidable ethical issues. Lymphocyte immunotherapy, a simple and cost effective method, can be safe and useful approach if performed with proper dose of fresh lymphocytes intradermally before and during pregnancy. Overall, cell therapy mechanism of actions are inducing the production of cytokines, blocking antibodies and growth factors, proliferation of B10 cells, reducing the activity of NK cells, increasingTh2 and Treg cells and decreasing Th1 and Th17 cells. Cell therapy can be an effective strategy as it provides an interactive, dynamic, specific and individualized treatment. Although cell therapy is a promising approach, it still needs more investigation in order to improve and make it safer. Unlabelled Image [ABSTRACT FROM AUTHOR]

• Recurrent pregnancy loss, also known as RPL, happens to 2–5% of women of reproductive age. • Immune system between the mother and the fetus plays an important role in the acceptance of the fetus and maintaining the pregnancy. • Modulation of the immune system by lymphocyte immunotherapy (LIT) is a reasonable way to prevent embryo rejection. • Pro-Inflammatory cytokines decline following subcutaneous LIT of women with RPL. In order to prevent miscarriage in RPL patients, the goal of this study was to determine how well lymphocyte immunotherapy (LIT) works in modifying immunological responses produced by cells, cytokines, transcription factors, and microRNAs. 200 RPL patients and 200 healthy controls were included in the study. Using flow cytometry, it was possible to compare the frequency of cells before and after lymphocyte treatment. Real-time PCR was used to assess the gene expression levels of transcription factors, cytokines, and microRNAs. ELISA method was used to evaluate the level of secretion of cytokines in the serum. Primary evaluation of the immune profile between healthy controls and RPL cases showed a higher frequency of Th17, NK, B cells and a lower frequency of Treg cells in RPL cases. Also, pro-inflammatory cytokines showed increased expression at mRNA and protein levels in the RPL group in comparison with the control group. Whereas, anti-inflammatory cytokines showed decreased expression in RPL patients. Decreased and increased frequency of Th17 and Treg lymphocytes observed in RPL cases following LIT, respectively. The same results obtained for RORγt and FoxP3 mRNA expression as transcription factor of Th17 and Treg cells, respectively. NK cell cytotoxicity decreased after LIT in RPL patients. miR-326a and miR-155 expression after LIT reduced, but miR-146a and miR-10a expression increased in RPL instances. LIT in RPL cases causes to elevation and modulation of anti-inflammatory and pro-inflammatory cytokines. Our data showed that lymphocyte therapy can be proposed as an effective therapeutic agent in RPL patients with immunological background by a modulating inflammatory condition. [ABSTRACT FROM AUTHOR]

• Recurrent pregnancy loss (RPL) is a one of the most complications of pregnancy. • Metabolic syndrome induces reactive oxygen species production in inflammatory conditions. • Oxidative stress is one of the substantial factors affecting the pathophysiology of pregnancies and considered as one of the potential causes of idiopathic RPL. • We hypothesized that oxidative stress is a key factor behind the link between metabolic syndrome and the risk of RPL. Recurrent pregnancy loss (RPL) is defined as three or more consecutive pregnancy losses prior to the 20th week of gestation. Exaggerated maternal immune response and oxidative stress status have been proposed as one of the main underlying mechanisms for RPL. The aim of this study was to evaluate the role of inflammatory pathway and oxidative stress imbalance in RPL patients with or without metabolic syndrome (MetS). 21 and 28 RPL patients with (RPL-MS) and without (RPL-NMS) metabolic syndrome were enrolled in this clinical study. 42 healthy women also were considered as the control group. The levels of IL1β, IL6, IL17, TNFα, CCL2, CXCL8 were evaluated by ELISA method. Additionally, the oxidative stress biomarkers including TAS, TOS, NO, CAT, SOD, AOPP, MPO were analyzed by spectrophotometry. The expression levels of IL1β, IL6, IL17, TNFα, CCL2, CXCL8, NFĸB, AP1, miR-21, miR-146-a, miR-223 were also assessed by real time PCR. The frequency of Th17 and T-reg cells was also measured by flow cytometry. Significant increase in the expression levels of IL1β, IL6, IL17, TNFα, CCL2, CXCL8, NFĸB, AP1 and miR-21 was observed in RPL-MS patients. Furthermore, significant decreased expression levels of FoxP3, miR-146-a and miR-223 was also observed in RPL-MS group. The levels of IL1β, IL6, IL17, TNFα, CCL2, CXCL8, NO, MPO and TOS were found to be higher in RPL-MS group compared to the RPL-NMS and healthy controls. In contrast, the level of CAT and SOD in RPL-MS patients was decreased. The frequency of Th17 and Treg cells was also higher and lower in RPL-MS patients compared to the other groups, respectively. Our results support the concept that subclinical inflammatory state, oxidative stress and metabolic syndrome play a crucial role in the etiopathogenesis of RPL assisting clinicians for pregnancy consequences prediction. [ABSTRACT FROM AUTHOR]

Background Th17 cells and Treg cells have been proposed as new risk factors for recurrent miscarriage (RM). In this study, we investigated the effect of Intravenous immunoglobulin G (IVIG) on the levels and function of Th17 and Treg cells and pregnancy outcome in women with RM. Materials and methods 94 pregnant women with RM were enrolled in this study. Blood was drawn at the time of positive pregnancy. On the same day, IVIG 400 mg/kg was administered intravenously for 44 patients. 50 other RM patients were included as no IVIG interfering control group. Following the first administration, IVIG was given every 4 weeks through 32 weeks of gestation. Peripheral blood was drawn after the last administration (32 weeks after pregnancy). Results IVIG down-regulated Th17 cells population and function and up-regulated Treg cells population and function were significant in the treated group. Pregnancy outcome in IVIG treated subjects was successful in 38 out of 44 RM women (86.3%). However, pregnancy outcome was successful in 21 out of 50 untreated RM women (42%). Conclusion Administration of IVIG in RM women with cellular immune cells abnormalities during pregnancy influences Th17/Treg ratio in peripheral blood and enhances Treg and decreases Th17 responses. [ABSTRACT FROM AUTHOR]

Background Women with elevated natural killer (NK) cell frequency and function during pregnancy, suffer from recurrent pregnancy loss (RPL). In the present study, the possible effect of intravenous immunoglobulin (IVIG) administration on Th1 and Th2 cell frequency, cytokine secretion, and expression of transcription factors is compared between RPL patients and control group. Materials and methods Totally, 44 women with a history of RPL (32 women as treated group and 12 as control group) were enrolled in the study. The frequency of Th1 and Th2 lymphocytes, the expression of transcription factors related to these cells and the serum levels of associated cytokines were assessed by flowcytometry, real-time PCR and ELISA, respectively. All, assessments were performed both before and after treatment with IVIG. Results A significant reduction in Th1 lymphocyte frequency, transcription factor expression and cytokine levels were observed in IVIG-treated group, while all the above parameters indicated a significant increase for Th2 lymphocytes. Th1/Th2 ratio decreased significantly (p value < 0.0001) at the end of treatment and 28 out of 32 (87.5%) women in IVIG-treated group had live birth in comparison with 5 out of 12 (41.6%) in untreated group. Conclusion IVIG administration proves to be an efficient therapeutic strategy which is able to enhance the success rate of pregnancy through a shift in Th2 responses. Furthermore, IVIG presents efficacy for the treatment of reproduction failures especially in subjects with immune cell abnormalities and increased NK cell level and function. [ABSTRACT FROM AUTHOR]

The molecular mechanisms involved in the pathogenesis of recurrent pregnancy loss (RPL) are not completely recognized. The present study aimed to assess the molecules associated with ATP catabolism and hypoxia besides their related miRNAs in patients with RPL. The frequency of Th17 and Treg cells in PBMCs of RPL women and healthy pregnant women were evaluated with Flow cytometry. The expression levels of CD39, CD73, and Hypoxia-inducible factor-alpha (HIF-1α), miR-18a, miR-30a, and miR-206 in PBMCs of two groups were measured with real-time PCR and western blotting. Then, serum levels of IGF-1, TGF-β, and HIF-1α were measured by ELISA. Our results indicated a higher (p = 0.0002) and lower (p < 0.0001) frequency of Th17 and Treg lymphocytes in RPL women, respectively. The expression level of CD39 decreased in PBMCs of RPL women whereas the level of CD73 and HIF-α increased (p = 0.0010, 0.0023, 0.0006 respectively). The results of CD39 and CD37 were also confirmed by protein analysis (p = 0.0047, 0.0364 respectively). Almost, the same results for CD39 and CD73 expression at mRNA and protein levels were observed in isolated Treg cells. Moreover, we found the higher expression of miR-206 and miRNA-30a (p = 0.0038, 0.0123), but the lower expression of miRNA-18a (p = 0.0101) in RPL. The concentration level of IGF-1, and TGF-β reduced (p = 0.0017, 0.0065 respectively) while the level of HIF-α elevated (p = 0.0235) in serum samples of RPL. In conclusion, we observed the dysregulation of molecules that are involved in ATP catabolism and hypoxia, including CD39, CD73, and HIF-1a which is related to miR-18a, miR-30a, and miR-206 change in RPL women. It may be potentially used for RPL prognosis by more comprehensive future studies. • The molecular mechanisms are involved in the pathogenesis of RPL are not completely recognized. • Dysregulation of molecules that are involved in ATP catabolism and hypoxia is observed in RPL. • miR-18a, miR-30a, and miR-206 expression changes are altered hypoxia and ATP catabolism condition in RPL patients. [ABSTRACT FROM AUTHOR]

There has been limited study on the impact of PBMC therapy in RSA patients with immunological disorders such as Th17 and Treg cell dysregulation, as well as their associated factors. This study aimed to assess the efficacy of PBMC therapy in modulating immune cell frequency, cytokine production, transcription factors, and miRNAs implicated in the regulation of their function, as well as their potential superiority to routine treatments. Fifty RSA women who had received PBMCs and 50 matched-paired control RSA women who had received the routine treatments were recruited and followed for three months. The frequencies of Th17, Treg, NK, and B cells were assessed using flow cytometry. Thereafter, the gene expression level of the transcription factors and related miRNAs of Treg cell and Th17 cell was quantified using RT-PCR. Then ELISA was employed to assess the cytokine production of Th17 and Treg cells. Finally, the live birth rate and miscarriage rate were evaluated as clinical outcomes in this study. Flow cytometry analysis revealed that PBMC therapy significantly reduces the frequencies of Th17 and NK cells while enhancing the frequency of Treg cells. RT-PCR analysis confirmed that PBMC therapy significantly downregulates RORγt and upregulates FoxP3. Likewise, RT-PCR analysis showed that PBMC therapy reduces the expression of miR-25, miR-155, and miR-326 while increasing the expression of miR-10a. ELISA results demonstrated that PBMC therapy considerably decreases the concentration of inflammatory cytokines IL-1β, IL-17, and TNF-α and enhances the concentration of anti-inflammatory cytokines IL-10 and TGF-β. Following PBMC therapy live birth rate raised while miscarriage rate reduced. Our findings suggested that, in contrast to routine treatments, PBMC therapy can significantly modulate the maternal immune system by enhancing the Treg/Th17 paradigm and regulating the expression of Treg and Th17 cell-associated cytokines, transcription factors, and miRNAs. This treatment also can increase the live birth rate in RSA patients. • LIT had superior immunomodulatory effects in RSA patients as compared to routine treatments. • LIT can effectively target the Treg/Th17 paradigm by directing the expression of cytokines, transcription factors, and miRNAs toward Treg cell immunodominance. • Many studies are still warranted to corroborate our findings and establish LIT as a viable therapeutic approach for RSA women. [ABSTRACT FROM AUTHOR]

• Decrease in IL-10-producing B cells and their related IL-10 in woman with RPL. • Negative association between the percentage of IL-10-producing B cells and level of serum autoantibodies in RPL patients. • Lower levels of IL-1-producing B cells were found in patients with larger number of miscarriages. Interleukin (IL)-10-producing B cells are recently known for their regulatory function in several disorders. However, the possible role of these cells remains unclear in recurrent pregnancy loss (RPL) pathogenesis. Total B cells from 24 RPL patients with cellular immune abnormalities, as well as that of 25 normal pregnant women were cultured and stimulated by Toll Like Receptor (TLR) agonists (CpG oligodeoxynucleotides (ODN) and imiquimod). Then, the frequency of IL-10+ CD19+ B cells was found out using flow cytometry. Enzyme-linked immunosorbent assay (ELISA) was used to assess the levels of IL-10 in supernatant medium and serum of stimulated B cells, as well as those of several serum autoantibodies. Real-Time PCR method was carried out for determining the IL-10 expression level and specific genes transcripts. RPL patients indicated a lower proportion of IL-10+ CD19+ B cells, and reduced levels of IL-10 in both serum and supernatant of the culture medium of the stimulated B cells. According to the results, total IgG levels was greater in serum of RPL patients in comparison with healthy pregnant women. Similarly, the percentage of these cells was negatively correlated with serum total IgG levels and the number of miscarriages. The expression levels of the mRNA of programmed death-ligand 1 (PD-L1) and IL-10 were lower in RPL patients, while those of x binding protein 1 (XBP-1), interferon regulatory factor 4 (IRF4), and B lymphocyte-induced maturation protein 1 (BLIMP1) were significantly increased. These observations indicated that the reduction in the population of peripheral blood IL-10-synthesizing B cells may prompt RPL pathogenesis, suggesting suppressive effects of these cells on autoantibody production and successful pregnancy outcomes. [ABSTRACT FROM AUTHOR]

• Implantation failure is one of the factors contributing to pregnancy rate reduction after IVF. • Local immunological cells and factors at implantation site play an important role in pregnancy process. • PBMC-therapy has positive effect, by developing required initial inflammation for implantation. Infertility is one of the most common problems among couples worldwide. Recurrent pregnancy loss, premature ovarian failure, recurrent implantation failure and etc. are common high prevalence disorders in societies. We will review the definition, causes and treatment of recurrent implantation failure disorder in recent studies. Implantation refers to the attachment of the embryo to the endometrial luminal surface and recurrent implantation failure (RIF) is defined as the failure to achieve a pregnancy after transferring high-grade embryos through at least three in vitro fertilization (IVF) cycles to the endometrium. The embryo factors, maternal age, uterine factors, and multifactorial effectors have been considered as the causes of implantation failure. In this review, we aim to focus on immunological factors and cells such as pro-inflammatory cytokines and dendritic cells, macrophages, decidual and uterine NK cells, as well as Th-1 cells. There are different types of treatment according to the cause of RIF including aspirin and low-molecular-weight heparin therapy, immunosuppressive drugs, intravenous immunoglobulins, and hydroxychloroquine. Among immunological recurrent implantation failure therapy, we will discuss the intrauterine PBMC-therapy in detail. [ABSTRACT FROM AUTHOR]