Maternal anti-placental cell-mediated reactivity and spontaneous abortions

Increasing number of implantation failures and pregnancy losses associated with elevated Th1/Th2 cell ratio

PROBLEM

We aimed to assess whether an imbalance of T-helper (Th) 1 and Th2 cells contributes to implantation failure and pregnancy loss.

METHOD OF STUDY

In this cross-sectional study, 197 consecutive patients with a history of repeated implantation failure (RIF) after three or more embryo transfer (ET) cycles and/or recurrent pregnancy loss (RPL) after two or more clinical pregnancy losses underwent Th cell testing. After excluding 42 women aged ≥44 and 9 with vitamin D supplementation, we recruited 146 women including 79 with RIF and 81 with RPL. Fourteen women had a history of both RIF and RPL. We also recruited 45 fertile women and 40 general infertile women without a history of in vitro fertilization treatment. This study was approved by the local ethics committee.

RESULTS

There was no significant difference in IFN-γ-producing Th1 and IL-4-producing Th2 cell levels between the fertile and general infertile women, but Th1 cell levels and the Th1/Th2 cell ratio were significantly higher in the women with ≥4 ET cycles and ≥2 pregnancy losses than in the fertile and general infertile women. In the general infertile women, the total livebirth rates including natural conception after two ET cycles in the normal and high Th1/Th2 groups (Th1/Th2 <11.8 and ≥11.8, respectively) were 66.7% and 87.5%, respectively (p = .395).

CONCLUSIONS

A high Th1/Th2 cell ratio was linked to ≥4 implantation failure cycles and ≥2 pregnancy losses but not to general infertility.

Myeloid-derived suppressor cells are bound and inhibited by anti-thymocyte globulin

Myeloid-derived suppressor cells (MDSCs) inhibit T cell responses and are relevant to cancer, autoimmunity and transplant biology. Anti-thymocyte globulin (ATG) is a commonly used T cell depletion agent, yet the effect of ATG on MDSCs has not been investigated. MDSCs were generated in Lewis Lung Carcinoma 1 tumor-bearing mice. MDSC development and function were assessed in vivo and in vitro with and without ATG administration. T cell suppression assays, RT-PCR, flow cytometry and arginase activity assays were used to assess MDSC phenotype and function. MDSCs increased dramatically in tumor-bearing mice and the majority of splenic MDSCs were of the polymorphonuclear subset. MDSCs potently suppressed T cell proliferation. ATG-treated mice developed 50% fewer MDSCs and these MDSCs were significantly less suppressive of T cell proliferation. In vitro, ATG directly bound 99.6% of MDSCs. CCR7, L-selectin and LFA-1 were expressed by both T cells and MDSCs, and binding of LFA-1 was inhibited by ATG pre-treatment. Arg-1 and PD-L1 transcript expression were reduced 30–40% and arginase activity decreased in ATG-pretreated MDSCs. MDSCs were bound and functionally inhibited by ATG. T cells and MDSCs expressed common Ags which were also targets of ATG. ATG may be helpful in tumor models seeking to suppress MDSCs. Alternatively, ATG may inadvertently inhibit important T cell regulatory events in autoimmunity and transplantation.

Myeloid-Derived Suppressor Cells and Their Potential Application in Transplantation

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immunosuppressive cells of the myeloid lineage upregulated by mediators of inflammation, such as IL-2, granulocyte colony-stimulating factor, and S100A8/A9. These cells have been studied extensively by tumor biologists. Because of their robust immunosuppressive potential, MDSCs have stirred recent interest among transplant immunologists as well. MDSCs inhibit T-cell responses through, among other mechanisms, the activity of arginase-1 and inducible nitric oxide synthase, and the expansion of T regulatory cells. In the context of transplantation, MDSCs have been studied in several animal models, and to a lesser degree in humans. Here, we will review the immunosuppressive qualities of this important cell type and discuss the relevant studies of MDSCs in transplantation. It may be possible to exploit the immunosuppressive capacity of MDSCs for the benefit of transplant patients.

Sildenafil (Viagra®) blocks inflammatory injury in LPS-induced mouse abortion: A potential prophylactic treatment against acute pregnancy loss?

INTRODUCTION

Recurrent pregnancy losses (RPL) are common women's health issues. Inflammatory and thrombotic events have been associated with RPL including excessive production of cytokines, in particular TNF-α. However, mechanisms behind gestational losses are not yet fully understood. Sildenafil inhibits phosphodiesterase Type-5 (PDE5). This drug increases intracellular cyclic guanosine monophosphate, having vasodilatory and, more recently described, anti-inflammatory properties. PDE5 is present in murine and human uterus and placenta. Sildenafil is already used clinically for treatment of human fetal growth restriction (FGR). Our objective was to determine if Sildenafil alone or in combination with Heparin had protective effects in pregnant Swiss albino challenged to abort by lipopolysaccharide (LPS).

METHODS

Treatments (Sildenafil (50 mg/kg/day), Heparin (500 IU/Kg/day) or Sildenafil + Heparin at the same doses) were initiated the morning of copulation plug detection (gestational day (gd0)). On the 15th day of pregnancy, an intra-peritoneal injection of LPS (100 μg/kg) was administered. Untreated, pregnant mice challenged by LPS served as controls.

RESULTS

Assessments at 48 h after LPS revealed that Sildenafil + Heparin prevented fetal loss. Early assessments at 2 h after LPS indicated that the pretreatments prevented induction of inflammatory cytokine production (TNF-α, IL-1β/NF-κβ) and preserved placental histopathology.

DISCUSSION

Combined Sildenafil + Heparin therapy was superior to either treatment alone in most analyses. The known safety of Sildenafil and Heparin in human pregnancy suggests that usage of these combined agents may be of value for treatment of patients with impending pregnancy loss or prophylactically in women with a history of recurrent miscarriages.

Effects ofRadix scutellariaeandRhizoma atractylodison LPS-Induced Abortion and the Uterine IL-10 Contents in Mice

In the present study, lipopolysaccharide (LPS) was injected i.v. via the tail vein (0.1 μg per mouse) to induce abortion (embryo resorption) in Kunming mice. The interleukin 10 (IL-10) contents in the uterus were assayed by ELISA. The results revealed that the IL-10 level was significantly decreased in the LPS-induced abortion group of mice compared to the controls. Use of Pentoxifylline (PXF), or a combination of Radix scutellariae and Rhizoma atractylodis reversed the LPS effects: bringing down the fetal resorption rate, and increasing the IL-10 level significantly. The study indicates that the anti-abortive effects of PXF and the combination of Radix scutellariae and Rhizoma atractylodis are closely related to up-regulation of the Th 2 cytokine IL-10 at the maternal fetal interface.

Dydrogesterone supplementation in women with threatened preterm delivery--the impact on cytokine profile, hormone profile, and progesterone-induced blocking factor

Progesterone is indispensable in creating a suitable endometrial environment for implantation, and also for the maintenance of pregnancy. Successful pregnancy depends on an appropriate maternal immune response to the fetus. A protein called progesterone-induced blocking factor (PIBF) acts by inducing Th2-dominant cytokine production to mediate the immunological effects of progesterone. The aim of this prospective study was to compare serum concentrations of progesterone (P), estradiol (E2), anti-inflammatory (IL-10) and pro-inflammatory (IL-6, TNFα, IFNγ) cytokines, and serum PIBF concentrations in women with threatened preterm delivery who were given progesterone supplementation (study group) with those of women with threatened preterm delivery who were not given progesterone supplementation (control group). After dydrogesterone treatment of patients in the study group, serum PIBF as well as progesterone concentrations significantly increased. Women in this group had significantly higher serum levels of IL-10 than controls. The length of gestation was significantly higher in the group of women who were given progesterone supplementation. Our data suggest that dydrogesterone treatment of women at risk of preterm delivery results in increased PIBF production and IL-10 concentrations, and lower concentrations of IFNγ.

Toll-like receptor-2 and toll-like receptor-4 expression on maternal neutrophils during pregnancy

PROBLEM

Toll-like receptors (TLR) are an important part of the innate immune system and are present in a variety of human tissues. Work investigating the role of the TLR in pregnancy has thus far focused on placental tissue; however, minimal data is currently available concerning TLR expression in other tissues. Unlike placental tissue, neutrophils are easily retrievable during pregnancy and thus allow assessment of TLR’s prior to delivery.

METHOD OF STUDY

Using real time quantitative PCR this study investigated whether TLR-2 and TLR-4 expression on maternal neutrophils is altered throughout gestation or at the time of labor. A group of 12 non-pregnant women and two groups of ten pregnant patients were enrolled and followed longitudinally, one group throughout gestation and one group throughout the third trimester.

RESULTS

Although increased in the placenta, TLR2 and TLR4 expression on maternal neutrophils changes minimally throughout gestation.

CONCLUSION

There appears to be very little regulation of TLR2 and TLR4 at the mRNA level during normal pregnancy and labor. However, now that the normal values of TLR expression on maternal neutrophils have been determined it will be possible to compare them to those from pregnancies complicated by such conditions as preeclampsia, preterm labor, or preterm premature rupture of membranes.

Inhibition of MHC class II gene expression in uveal melanoma cells is due to methylation of the CIITA gene or an upstream activator

Most cells with an intact interferon-gamma receptor and signaling pathway are able to express MHC class II molecules when treated with cytokines such as interferon-gamma and tumor necrosis factor-a. Interestingly, primary uveal melanocytes and most ocular melanoma cells are resistant to interferon-gamma mediated induction of class II MHC genes. This unusual phenotype is hypothesized to be germane to the immune-privileged status to the eye. Via a series of experiments, we have probed the molecular basis of this class II MHC resistant phenotype. We have analyzed the methylation status of the gene encoding the class II transactivator (CIITA), and asked whether treatment of class II MHC resistant ocular melanoma cells with the demethylating agent 5'-azacytidine can restore interferon-gamma inducibility of these class II MHC genes in these cells. The data obtained suggest that the specific blockade in cytokine-induced class II MHC gene expression is due to a suppression of the gene encoding the class II transactivator (CIITA). Treatment with 5' azacytidine restores the ability of these cells to express class II MHC genes upon interferon-gamma treatment. Whilst this is reminiscent of what occurs in another immune-privileged tissue--the placental trophoblast--we show here that silencing of the CIITA gene in uveal melanocytes either involves methylation of distinct nucleotides from those detected in trophoblasts, or involves an upstream activator of CIITA gene expression.

An update in recurrent spontaneous abortion

Recurrent spontaneous abortion (RSA) is defined as three or more consecutive pregnancy losses prior to the 20th week of gestation. The etiology of recurrent spontaneous abortion is often unclear and may be multifactorial, with much controversy regarding diagnosis and treatment. Reasonably accepted etiologic causes include, genetics, anatomical, endocrine, placental anomalies, hormonal problems, infection, smoking and alcohol consumption, exposure to environmental factors, psychological trauma and stressful life event, certain coagulation and immunoregulatory protein defects. Detection of an abnormality in any of these areas may result into specific therapeutic measures, with varying degrees of success. However, the majority of cases of RSA remains unexplained and is found to be associated with certain autoimmune (APA, ANA, ACA, ATA, AECA) and alloimmune (APCA, Ab2, MLR-Bf) antibodies that may play major role in the immunologic failure of pregnancy and may lead to abortion. Alteration in the expression of HLA-G molecules, T-helper-1 (Th-1) pattern of cytokines and natural killer (NK) cells activity may also induce abortion. Various forms of treatment like antithrombotic therapies such as aspirin and heparin, intravenous immunoglobulin (IVIg) therapy, immunotherapy with paternal lymphocytes and vitamin D3 therapy are effective mode of treatment for unexplained cause of fetal loss in women with RSA.

Nerve growth factor and its functional receptor TrkA are up-regulated in murine decidual tissue of stress-triggered and substance P-mediated abortion

PROBLEM

Stress, elicited by environmental and social conditions, is known to affect the homeostasis of the nervous, endocrine and immune systems. In pregnancy, perceived stress results in a predomination of inflammatory abortion-associated Th1 cytokines over immunosuppressive, pregnancy-protective-associated Th2 cytokines, putatively via neuropeptide substance P (SP). Nerve growth factor (NGF), an important trophic factor for sympathetic neurons, has been implicated in the responsiveness of immune-competent cells through its functional receptor, tropomyosin receptor kinase (TrkA). Thus, the aim of the present study was to identify a cross-talk between distinct neurotrophic and immune mediators in pregnancy maintenance.

METHOD OF STUDY

Using immune fluorescence, we evaluated decidual and placental expression of NGF and TrkA on gestation day (gd) 13.5 in the abortion-prone mouse model CBA/J x DBA/2J in (1) CBA/J female control mice; (2) CBA/J mice exposed to stress on gd 5.5; and (3) CBA/J mice injected with SP on gd 5.5 to mimick stress perception.

RESULTS

Stress and SP injection significantly increased the abortion rate and up-regulated decidual NGF and TrkA expression compared with the control. Stress, but not SP injection down-regulated placental NGF, whereas no changes in placental TrkA were observed.

CONCLUSION

Our data suggest a functional role for NGF in stress-triggered, SP-mediated abortion.

The cell-mediated immune response to Neospora caninum during pregnancy in the mouse is associated with a bias towards production of interleukin-4

Neospora caninum is an obligate intracellular protozoan parasite which is efficiently transmitted transplacentally in cattle where it may cause abortion. A pregnant mouse model was used to characterise the immune response following N. caninum infection; the response in non-pregnant and pregnant mice was compared. Spleen cells from both infected/non-pregnant and infected/pregnant mice produced interferon-gamma, interleukin-12 and tumour necrosis factor alpha; however, the levels of these Th1 cytokines were lower in infected/pregnant mice. Infected/non-pregnant and infected/pregnant mice also produced the Th2 cytokine interleukin-10; however, there was no trend toward a decrease of this in pregnant mice. Interleukin-4 was exclusively produced at high levels by infected/pregnant mice and thus appears responsible for the observed decline in Th1 cytokine production in pregnant mice. A bias towards Th2 cytokines such as IL-4 and IL-10 is normally associated with the maintenance of a viable pregnancy, and not with the control of protozoal infections. Consequently, the importance and role of cytokines and cell-mediated immunity in the control of transplacental transmission and foetal loss due to N. caninum infection are discussed.

Sex differences in in vitro pro-inflammatory cytokine production from peripheral blood of multiple sclerosis patients

We compared the patterns of the pro-inflammatory cytokines, interferon-gamma (IFN-gamma), interleukin-2 (IL-2) and tumor necrosis factor-alpha (TNF-alpha), and the anti-inflammatory cytokines, interleukin-10 (IL-10) and tumor growth factor-beta (TGF-beta) from peripheral blood of male and female patients with relapsing-remitting (RR) and secondary progressive (SP) forms of multiple sclerosis (MS). The relationships between pro-inflammatory cytokines and disability (expanded disability status scale, EDSS) were also examined. Peripheral blood anti-coagulated with heparin was obtained from 47 MS patients (30 women and 17 men) and activated with phorbol-12-myristate 13 acetate (PMA) and ionomycin in the presence of brefeldin A and stained for flow cytometry with fluorescently labeled antibodies against intracellular IFN-gamma, TNF-alpha, IL-2, IL-4 and IL-10. The T cells were delineated with peridinin chlorophyll protein (Per-CP) labeled anti-CD3 antibody. The stained samples were analyzed on a flow cytometer to assess the intracellular pro-inflammatory cytokine patterns. The levels of interleukin-10 (IL-10) and tumor growth factor-beta (TGF-beta) were measured in plasma using enzyme-linked immunoassay. The percentage of TNF-alpha-producing CD3 positive cells was significantly higher (P=0.045) in men (mean+/-S.D., 39+/-13%) than in women (mean+/-S.D., 29+/-13%) RR-MS patients. The percentage of CD3 positive cells producing IFN-gamma was significantly correlated with EDSS in females but not in males (Spearman rank correlation r(S)=0.49, P=0.018). The secretion of the pro-inflammatory cytokines, IFN-gamma and TNF-alpha, is influenced by gender in MS patients and may contribute to the sexual dimorphism of MS.

HLA-G has a concentration-dependent effect on the generation of an allo-CTL response

Human leucocyte antigen (HLA) -G is expressed on trophoblast cells during pregnancy, suggesting a role in protection of the semiallogeneic fetus. Published data suggest that HLA-G protects a cell against natural killer cell lysis. It has been hypothesized that HLA-G may also protect the fetus by preventing allo-cytotoxic T lymphocyte (CTL) responses. To test this hypothesis, we assayed the effects of various concentrations of purified HLA-G on CTL response in a mixed lymphocyte culture (MLC) system. We found that concentrations > or =0.1 microg/ml of HLA-G suppressed the allo-CTL response by 30-100% over the control, but, paradoxically, concentrations of 0.01-0.05 microg/ml of HLA-G augmented the allo-CTL response by 25-50% over the control. Concentrations < or = 0.001 microg/ml HLA-G had no effect. Addition of HLA-G to preprimed allo-CTL effector cells did not affect their killing ability. Allo-CTL suppressive doses of HLA-G induced a T helper type 2 (Th2) cytokine response, whereas allo-CTL-enhancing doses of HLA-G induced a Th1-type cytokine response. HLA-G purified from first-trimester placenta does not affect allo-proliferative responses nor does it alter the percentage of CD4+ or CD8+ T cells in MLCs. These findings support a potential role for HLA-G-mediated suppression of allo-CTL formation in normal pregnancies. In addition, the effects observed at lower concentrations of HLA-G may have interesting implications for the condition of pre-eclampsia in which concentrations of this HLA class I molecule are reduced.

Cytokines and placental macrophages in regulation of birth activity

The article reviews present notions on functional activity of cytokines of the fetoplacental complex. Particular emphasis is placed on the role of these molecules in the regulation of gestation processes and in pregnancy incompetence. The mechanism of the involvement of placental macrophages and their products in gestation and delivery is discussed.

Maternal Th1- and Th2-type reactivity to placental antigens in normal human pregnancy and unexplained recurrent spontaneous abortions

Spontaneous abortion is the most common complication of pregnancy, but the etiology of a significant proportion of abortions is still unknown. We have examined the production of Th1- and Th2-type cytokines by women with unexplained recurrent spontaneous abortion (RSA) since it appears that successful murine pregnancy occurs in a Th2-dominant situation and that Th1-type immunity is associated with pregnancy failure. We have compared maternal reactivity toward placental antigens in women with a history of successful pregnancy with that in women with a history of RSA. This was done by coculturing maternal peripheral blood mononuclear cells (PBMC) with autologous placental cells and also by stimulating maternal PBMC with antigens from a choriocarcinoma cell line of trophoblastic origin. We detected significantly greater levels of the Th2 cytokines IL-6 and IL-10 in normal pregnancy compared to unexplained RSA and significantly higher levels of the Th1 cytokine IFN-gamma in RSA compared to normal pregnancy. These results suggest that women with normal pregnancy have a higher Th2 bias, while women with a history of RSA evince a bias toward Th1-type reactivity.

Th1 and Th2 T helper cell subsets affect patterns of injury and outcomes in glomerulonephritis

The recognition that human immune responses can be directed by two different subsets of T helper cells (Th1 and Th2) has been an important development in modern immunology. Immune responses polarized by either the Th1 or Th2 subset predominance result in different inflammatory effector pathways and disease outcomes. Many autoimmune diseases are associated with either Th1- or Th2- polarized immune responses. Although these different immune response patterns are relevant to glomerulonephritis (GN), little attention has been paid to the consequences of Th1 or Th2 predominance of nephritogenic immune responses for the pattern and outcome of GN. Unlike other autoimmune conditions, GN results from a variety of different immune responses and has a range of histologic features and immune effectors in glomeruli. This review assesses the data available from studies of experimental and human GN that address the Th1 or Th2 predominance of nephritogenic immune responses and their relevance to the different histopathological patterns and outcomes of GN. In particular, the evidence that Th1-predominant nephritogenic immune responses are associated with severe proliferative and crescentic GN is presented.

Pregnancy Ameliorates Induction and Expression of Experimental Autoimmune Uveitis

Female patients suffering from autoimmune uveitis are reported to experience a temporary remission during pregnancy. Experimental autoimmune uveitis (EAU) is a model for human uveitis. Here we examine the effect of pregnancy on the development of EAU and its associated immunological responses. Susceptible C57BL/6 mice were immunized with interphotoreceptor retinoid-binding protein (IRBP). EAU scores and Ag-specific responses were evaluated 21 days later. Mice immunized during pregnancy developed significantly less EAU than nonpregnant controls. Their lymph node cells and splenocytes produced a distinct pattern of cytokines in response to IRBP: reduced IFN-γ and IL-12 p40, but unchanged levels of TNF-α, IL-4, IL-5, and IL-10. Anti-IRBP Ab isotypes revealed an up-regulation of IgG1, indicating a possible Th2 bias at the humoral level. Ag-specific proliferation and delayed hypersensitivity, as well as mitogen-induced IFN-γ production, remained undiminished, arguing against an overall immune deficit. Interestingly, pregnant mice that received an infusion of IRBP-primed lymphoid cells from nonpregnant donors also developed reduced EAU, suggesting that pregnancy suppresses not only the generation, but also the function of mature uveitogenic effector T cells. Pregnant mice at the time of immunization exhibited elevated levels of TGF-β, but not of IL-10, in the serum. We suggest that protection from EAU during pregnancy is due primarily to a selective reduction of Ag-specific Th1 responses with only marginal enhancement of Th2 function, and that these effects may in part be secondary to elevated systemic levels of TGF-β.

Analysis of human leukocyte antigen-G polymorphism including intron 4 in Japanese couples with habitual abortion

PROBLEM

The purpose of this study was to clarify whether there is a difference between the allele frequency of human leukocyte antigen (HLA)-G in healthy Japanese people and that of Japanese couples with habitual abortion.

METHOD OF STUDY

Exons 2, 3, 4, and intron 4 of the HLA-G gene were analyzed in 20 couples with habitual abortion, using polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) analysis. Intron 4 of the HLA-G gene was also analyzed in 54 healthy individuals. The nucleotide sequence of the PCR product of intron 4 was further determined by direct sequencing.

RESULTS

Two kinds of nucleotide sequence were identified in intron 4 of the HLA-G gene, one of which was identical to that of HLA-G*01011, and the other was identical to that of HLA-G*01012, G*01013, and G*0104. The frequency of each allele in affected women and their husbands did not significantly differ from that of healthy individuals, and no mutation was found in any affected couple.

CONCLUSION

HLA-G allelic abnormality seemed to have little, if any, implication in the pathogenesis of habitual abortion.

Why did your mother reject you? Immunogenetic determinants of the response to environmental selective pressure expressed at the uterine level

PROBLEM

Maternal "rejection" of the implanted conceptus is considered to account for a significant proportion of miscarriages (abortions) in both humans and animals. Our understanding of mechanisms has been limited, and hence, explanations for nonrejection have remained largely speculative. Losses, when they occur, could represent either random accidental failure of protective mechanisms or a more purposeful discrimination.

METHOD OF STUDY

An analysis of the most recent data.

RESULTS AND CONCLUSIONS

The embryo is most akin to a parasite, and pregnancy is most akin to a host-parasite interaction. If one excludes chromosome abnormalities in the embryo as a cause of death, activation of coagulation mechanisms, leading to vasculitis affecting the maternal blood supply to the implanted embryo, appears to represent a major loss-causing mechanisms--a form of ischemic autoamputation. Proinflammatory T-helper (Th) 1-type cytokines trigger this process via upregulation of a novel prothrombinase, fgl2. Th2/3 cytokines, such as interleukin (IL)-4, IL-10, and transforming growth factor (TGF)-beta 2, may antagonize the processes involved. Cytokine balance is determined by the genetics of the mother, which regulate her response to stress; endotoxin (LPS); and paternal antigens, selectively expressed on the trophoblast of the embryo, via imprinting. Based on studies in abortion-prone mice, where immunity to paternal alloantigens prevents loss, three distinct gene products in the embryo are proposed to determine the cytokine response to maternal lymphomyeloid cells in the uterus.

Peripheral blood mononuclear cells from women with recurrent abortion exhibit an aberrant reaction to release cytokines upon the direct contact of human leukocyte antigen-G-expressing cells

PROBLEM

In search for pathogenesis of recurrent abortion, we examined whether lymphocytes/macrophages from women with recurrent abortion exhibited an aberrant ability to release cytokines upon the direct contact of human leukocyte antigen (HLA)-G.

METHOD OF STUDY

The amounts of cytokines released from peripheral blood mononuclear cells (PBMCs) from women with recurrent abortion were compared with those from normal multiparous women or normal nulligravidous women when cocultured with or without HLA-G-expressing target cells.

RESULTS

When cocultured with HLA-G-expressing target cells, the amount of interleukin-1 beta released from PBMCs was increased in recurrent aborters whereas it decreased in both normal multiparous and nulligravidous women. The amount of interleukin-3 released from PBMCs did not differ with or without HLA-G-expressing cells in recurrent aborters, whereas it increased in the presence of HLA-G-expressing cells in normal controls. The amount of tumor necrosis factor-alpha released from PBMCs was decreased in the presence of HLA-G-expressing cells in both recurrent aborters and normal controls.

CONCLUSION

The aberrant reaction of maternal lymphocytes/macrophages in releasing cytokines upon the contact of HLA-G expressed on trophoblasts may impact negatively on trophoblastic growth, which may be pathogenic in recurrent abortion.