Natural killer, natural killer T, helper and cytotoxic T cells in the decidua from sporadic miscarriage

The role of neutrophils in chorioamnionitis

Chorioamnionitis, commonly referred to as intrauterine infection or inflammation, is pathologically defined by neutrophil infiltration and inflammation at the maternal-fetal interface. Chorioamnionitis is the common complication during late pregnancy, which lead to a series of serious consequences, such as preterm labor, preterm premature rupture of the fetal membranes, and fetal inflammatory response syndrome. During infection, a large number of neutrophils migrate to the chorio-decidua in response to chemokines. Although neutrophils, a crucial part of innate immune cells, have strong anti-inflammatory properties, over-activating them can harm the body while also eliminating pathogens. This review concentrated on the latest studies on chorioamnionitis-related consequences as well as the function and malfunction of neutrophils. The release of neutrophil extracellular traps, production of reactive oxygen species, and degranulation from neutrophils during intrauterine infection, as well as their pathological roles in complications related to chorioamnionitis, were discussed in detail, offering fresh perspectives on the treatment of chorioamnionitis.

Immune phenotype of the endometrium in patients with recurrent implantation failures after the transfer of genetically tested embryos in assisted reproductive technology programs

Recurrent implantation failures (RIF) in assisted reproduction programs are one of the most challenging problems. Among the factors that can adversely affect implantation, endometrial immune structural disorders may be one of the leading causes. The aim of our work was to study the immune features of the endometrium in women with RIF after genetically tested embryo transfer in comparison with fertile gestational carriers. Immune cells in endometrial samples were studied by flow cytometry and RNA expression of IL (interleukin)15, IL18, fibroblast growth factor-inducible 14 receptor (Fn14), and tumor necrosis factor-like weak inducer of apoptosis (TWEAK) by reverse polymerase chain reaction. In one-third of the cases, a unique immune profile of the endometrium, which we called the not transformed endometrial immune phenotype, was found. It is characterized by a combination of features, such as high expression of HLA-DR on natural killers (NK), increased fraction of CD16 + , and a decreased fraction of CD56bright endometrial NK. In addition, when compared to gestational carriers, patients with RIF had a greater discrepancy between IL18 mRNA expression data, reduced mean TWEAK and Fn14 levels, and increased IL18/TWEAK and IL15/Fn14 ratios. Immune abnormalities that were found in more than half of the patients (66.7 %) may be the cause of implantation failures in genetically tested embryo transfer programs.

Breast cancers co-opt normal mechanisms of tolerance to promote immune evasion and metastasis

Normal developmental processes, such as those seen during embryonic development and postpartum mammary gland involution, can be reactivated by cancer cells to promote immune suppression, tumor growth, and metastatic spread. In mammalian embryos, paternal-derived antigens are at risk of being recognized as foreign by the maternal immune system. Suppression of the maternal immune response toward the fetus, which is mediated in part by the trophoblast, is critical to ensure embryonic survival and development. The postpartum mammary microenvironment also exhibits immunosuppressive mechanisms accompanying the massive cell death and tissue remodeling that occurs during mammary gland involution. These normal immunosuppressive mechanisms are paralleled during malignant transformation, where tumors can develop neoantigens that may be recognized as foreign by the immune system. To circumvent this, tumors can dedifferentiate and co-opt immune-suppressive mechanisms normally utilized during fetal tolerance and postpartum mammary involution. In this review, we discuss those similarities and how they can inform our understanding of cancer progression and metastasis.

Immunological Changes in Pregnancy and Prospects of Therapeutic Pla-Xosomes in Adverse Pregnancy Outcomes

Stringent balance of the immune system is a key regulatory factor in defining successful implantation, fetal development, and timely parturition. Interference in these primary regulatory mechanisms, either at adolescence or prenatal state led to adverse pregnancy outcomes. Fertility restoration with the help of injectable gonadotrophins/progesterone, ovulation-inducing drugs, immunomodulatory drugs (corticosteroids), and reproductive surgeries provides inadequate responses, which manifest its own side effects. The development of a potential diagnostic biomarker and an effectual treatment for adverse pregnancy outcomes is a prerequisite to maternal and child health. Parent cell originated bi-layered-intraluminal nano-vesicles (30-150 nm) also known as exosomes are detected in all types of bodily fluids like blood, saliva, breast milk, urine, etc. Exosomes being the most biological residual structures with the least cytotoxicity are loaded with cargo in the form of RNAs (miRNAs), proteins (cytokines), hormones (estrogen, progesterone, etc.), cDNAs, and metabolites making them chief molecules of cell-cell communication. Their keen involvement in the regulation of biological processes has portrayed them as the power shots of cues to understand the disease's pathophysiology and progression. Recent studies have demonstrated the role of immunexosomes (immunomodulating exosomes) in maintaining unwavering immune homeostasis between the mother and developing fetus for a healthy pregnancy. Moreover, the concentration and size of the exosomes are extensively studied in adverse pregnancies like preeclampsia, gestational diabetes mellitus (GDM), and preterm premature rupture of membrane (pPROMs) as an early diagnostic marker, thus giving in-depth information about their pathophysiology. Exosomes have also been engineered physically as well as genetically to enhance their encapsulation efficiency and specificity in therapy for cancer and adverse pregnancies. Successful bench to bedside discoveries and interventions in cancer has motivated developmental biologists to investigate the role of immunexosomes and their active components. Our review summarizes the pre-clinical studies for the use of these power-shots as therapeutic agents. We envisage that these studies will pave the path for the use of immunexosomes in clinical settings for reproductive problems that arise due to immune perturbance in homeostasis either at adolescence or prenatal state.

The Inflammatory Cytokine Imbalance for Miscarriage, Pregnancy Loss and COVID-19 Pneumonia

Pregnancy can be defined a vascular event upon endocrine control. In the human hemo-chorial placentation the chorionic villi penetrate the wall of the uterine spiral arteries, to provide increasing amounts of nutrients and oxygen for optimal fetal growth. In any physiological pregnancy the natural maternal response is of a Th1 inflammatory type, aimed at avoiding blood loss through the arteriolar wall openings. The control of the vascular function, during gestation as in any other condition, is achieved through the action of two main types of prostanoids: prostaglandin E2 and thromboxane on the one hand (for vasoconstriction and coagulation), prostacyclin on the other (for vasodilation and blood fluidification). The control of the maternal immune response is upon the responsibility of the fetus itself. Indeed, the chorionic villi are able to counteract the natural maternal response, thus changing the inflammatory Th1 type into the anti-inflammatory Th2. Clinical and experimental research in the past half century address to inflammation as the leading cause of abortion, pregnancy loss, premature delivery and related pulmonary, cerebral, intestinal fetal syndromes. Increased level of Interleukin 6, Interleukin 1-beta, Tumor Necrosis Factor-alfa, Interferon-gamma, are some among the well-known markers of gestational inflammation. On the other side, COVID-19 pneumonia is a result of extensive inflammation induced by viral replication within the cells of the respiratory tract. As it may happen in the uterine arteries in the absence of an effective fetal control, viral pneumonia triggers pulmonary vascular coagulation. The cytokines involved in the process are the same as those in gestational inflammation. As the fetus breathes throughout the placenta, fetal death from placental thrombosis is similar to adult death from pulmonary thrombosis. Preventing and counteracting inflammation is mandatory in both conditions. The most relevant literature dealing with the above-mentioned concepts is reviewed in the present article.

Predictive role of endometrial T-bet/GATA3 ratio during mid-luteal phase for live birth in patients undergoing in vitro fertilization: A retrospective observational study

OBJECTIVES

To investigate whether endometrial T-bet (Th1 lineage-committed transcription factor)/GATA3 (Th2 lineage-committed transcription factor) ratio has predictive potential for embryo implantation in infertile women undergoing in vitro fertilization-embryo transfer (IVF-ET).

STUDY DESIGN

We performed a retrospective observational study. In total, this study included 319 infertile women (253 women as the development cohort and 66 women as the validation cohort). Samples were obtained by endometrial scratching in the mid-luteal phase before IVF-ET treatment.

MAIN OUTCOME MEASURES

Immunohistochemistry was utilized to analyze the expression levels of T-bet and GATA3 in the endometrium. Predictive value of endometrial T-bet/GATA3 for live birth were analyzed.

RESULTS AND CONCLUSIONS

In the development cohort, the T-bet/GATA3 ratio was significantly lower in women with live birth than those patients with non-live birth [0.148 (0.101, 0.212) vs. 0.246 (0.170, 0.399), P＜0.0001]. In the validation cohort, changes in endometrial T-bet/GATA3 were similar among these groups. The endometrial T-bet/GATA3 ratio was an independent predictor of live birth after correction for patient age, anti-Mullerian hormone (AMH), quality of embryos transferred and other clinical characteristics (aOR = 0.280, 95 % CI: 0.169-0.462, P＜0.001). We developed and validated that an endometrial T-bet/GATA3 ratio at the cut-off of 0.22 had significant predictive value for live birth (developmental cohort: AUC = 0.76, 95 % CI: 0.70-0.81, P < 0.0001. validation cohort: AUC = 0.85 95 % CI: 0.76-0.95, P < 0.0001). Our results suggest that elevated endometrial T-bet/GATA3 ratio is an independent marker of live birth in infertile patients.

The Role of Type I and Type II NKT Cells in Materno-Fetal Immunity

NKT cells represent a small but significant immune cell population as being a part of and bridging innate and adaptive immunity. Their ability to exert strong immune responses via cytotoxicity and cytokine secretion makes them significant immune effectors. Since pregnancy requires unconventional maternal immunity with a tolerogenic phenotype, investigation of the possible role of NKT cells in materno-fetal immune tolerance mechanisms is of particular importance. This review aims to summarize and organize the findings of previous studies in this field. Data and information about NKT cells from mice and humans will be presented, focusing on NKT cells characteristics during normal pregnancy in the periphery and at the materno-fetal interface and their possible involvement in female reproductive failure and pregnancy complications with an immunological background.

Local action of cytokines and immune cells in communication between the conceptus and uterus during the critical period of early embryo development, attachment and implantation - Implications for embryo survival in cattle: A review

Early embryo development, implantation and pregnancy involve a complex dialogue between the embryo and mother. In cattle this dialogue starts as early as days 3-4 when the embryo is still in the oviduct, and it continues to implantation. Immunological processes involving cytokines, mast cells and macrophages form an important part of this dialogue. Amongst the cytokines, interleukin-6 (Il-6) and leukemia inhibitory factor (LIF) are secreted by both the embryo and uterine endometrium and form part of an ongoing and reciprocating dialogue. Mast cells and macrophages populate the uterine endometrium during embryo development and are involved in achieving the correct balance between inflammatory and anti-inflammatory reactions at the uterus that are associated with embryo attachment and implantation. Embryo loss is the major cause of reproductive wastage in cattle, and livestock generally. A deeper understanding of immunological processes during early embryo development will help to achieve the next step change in the efficiency of natural and assisted breeding.

Gut and Reproductive Tract Microbiota Adaptation during Pregnancy: New Insights for Pregnancy-Related Complications and Therapy

Pregnancy is characterized by maternal adaptations that are necessary to create a welcoming and hospitable environment for the fetus. Studies have highlighted how the microbiota modulates several networks in humans through complex molecular interactions and how dysbiosis (defined as quantitative and qualitative alterations of the microbiota communities) is related to human pathologies including gynecological diseases. This review analyzed how maternal uterine, vaginal, and gut microbiomes could impact on fetus health during the gestational period. We evaluated the role of a dysbiotic microbiota in preterm birth, chorioamnionitis, gestational diabetes mellitus and pre-eclampsia. For many years it has been hypothesized that newborns were sterile organisms but in the past few years this paradigm has been questioned through the demonstration of the presence of microbes in the placenta and meconium. In the future, we should go deeper into the concept of in utero colonization to better understand the role of microbiota through the phases of pregnancy. Numerous studies in the literature have already showed interesting results regarding the role of microbiota in pregnancy. This evidence gives us the hope that microbiota modulation could be a novel strategy to reduce the morbidity and mortality related to pregnancy complications in the future.

Immunology and the immunological response to pregnancy

The immune system in humans is a complex system capable of discriminating self from non-self, and mounting appropriate allogenic immune responses to protect themselves from foreign organisms. This system is made up of two arms of defense: the first one is a non-specific arm (innate), in which humans are born with and do not require antigenic recognition. The second one is specific arm (humoral) involving B and T cells that are capable of mounting responses to particular antigen with immense specificity. Both of these systems importantly interact with each other to protect humans in the most effective and efficient manner. Defects or malfunctions in these systems can result in a variety of illnesses and conditions. The immunology of pregnancy is a very unique, highly controlled system, which allows for survival of a fetus (semi-allograft), whilst simultaneously protecting a pregnant woman. There are immune shifts in pregnancy, which are well established to facilitate maternal-fetal tolerance. This promotes the concept that the immune system is not suppressed, but instead modulated to facilitate a pregnancy and explain the differential response to various pathogens in pregnancy. During pregnancy, the development of a fetal immunological system also occurs with intricate interaction between the maternal and fetal interface. The mechanism is preterm and term birth is poorly understood, but the immunological response has been well documented for both the pathological and physiological scenarios.

The psychoneuroimmunology of pregnancy

Pregnancy is associated with a number of significant changes in maternal physiology. Perhaps one of the more notable changes is the significant alteration in immune function that occurs during pregnancy. This change in immune function is necessary to support a successful pregnancy, but also creates a unique period of life during which a female is susceptible to disease and, as we'll speculate here, may also contribute to mental health disorders associated with pregnancy and the postpartum period. Here, we review the known changes in peripheral immune function that occur during pregnancy and the postpartum period, while highlighting the impact of hormones during these times on immune function, brain or neural function, as well as behavior. We also discuss the known and possible impact of pregnancy-induced immune changes on neural function during this time and briefly discuss how these changes might be a risk factor for perinatal anxiety or mood disorders.

Vascular adaptation in pregnancy and endothelial dysfunction in preeclampsia

Maternal vascular adaptation to pregnancy is critically important to expand the capacity for blood flow through the uteroplacental unit to meet the needs of the developing fetus. Failure of the maternal vasculature to properly adapt can result in hypertensive disorders of pregnancy such as preeclampsia (PE). Herein, we review the endocrinology of maternal adaptation to pregnancy and contrast this with that of PE. Our focus is specifically on those hormones that directly influence endothelial cell function and dysfunction, as endothelial cell dysfunction is a hallmark of PE. A variety of growth factors and cytokines are present in normal vascular adaptation to pregnancy. However, they have also been shown to be circulating at abnormal levels in PE pregnancies. Many of these factors promote endothelial dysfunction when present at abnormal levels by acutely inhibiting key Ca²⁺ signaling events and chronically promoting the breakdown of endothelial cell-cell contacts. Increasingly, our understanding of how the contributions of the placenta, immune cells, and the endothelium itself promote the endocrine milieu of PE is becoming clearer. We then describe in detail how the complex endocrine environment of PE affects endothelial cell function, why this has contributed to the difficulty in fully understanding and treating this disorder, and how a focus on signaling convergence points of many hormones may be a more successful treatment strategy.

Divergence of helper, cytotoxic, and regulatory T cells in the decidua from miscarriage

PROBLEM

The aim of this prospective study was to evaluate phenotypic differences of helper T (Th), cytotoxic T (Tc), and regulatory T (Treg) cells in the deciduae of missed miscarriage with a normal chromosome karyotype of a fetus (MN) and missed miscarriage with an abnormal chromosome karyotype of a fetus (MA).

METHODS OF STUDY

The decidua of 19 MN and 28 MA was obtained. Additionally, the decidua of 15 induced abortion (IA) and the endometrium of 19 non-pregnant women (EM) were obtained. IFN-γ(+) , IL-17(+) , CD25(high) Foxp3(+) cells in CD4(+) (Th) cells, and IFN-γ(+) cells in CD8(+) (Tc) cells were evaluated by flow cytometry.

RESULTS

The percentages of IFN-γ(+) Tc and CD4(+) CD25(high) Foxp3(+) (Treg) cells in MN were significantly increased as compared with MA and IA. The percentage of IFN-γ(+) Th in MN was increased as compared with IA.

CONCLUSION

Activation of IFN-γ(+) Tc and Treg cells in the decidua might be associated with the pathophysiology underlying MN.

Vaginal Mucosal Homeostatic Response May Determine Pregnancy Outcome in Women With Bacterial Vaginosis: A Pilot Study

Bacterial vaginosis (BV) is considered as a trigger for an inflammatory response that could promote adverse pregnancy outcome (APO). We hypothesized that BV-related inflammation could be counterbalanced by anti-inflammatory and mucosal homeostatic responses that could participate in pregnancy outcomes.A total of 402 vaginal self-samples from pregnant women in their first trimester were screened by Nugent score. In this population, we enrolled 23 pregnant women with BV but without APO, 5 pregnant women with BV and developing APO, 21 pregnant women with intermediate flora, and 28 random control samples from pregnant women without BV or APO.BV without APO in pregnant women was associated with 28-fold interleukin-8, 5-fold interleukin-10, and 40-fold interleukin-22 increases in expression compared to controls. BV associated with APO in pregnant women shared 4-fold increase in tumor necrosis factor, 100-fold decrease in interleukin-10, and no variation in interleukin-22 expressions compared to controls. Next-generation sequencing of vaginal microbiota revealed a shift from obligate anaerobic bacteria dominance in BV without APO pregnant women to Lactobacillus dominance microbiota in BV with APO.Our results show that the anti-inflammatory and mucosal homeostatic responses to BV may determine outcome of pregnancy in the setting of BV possibly through effects on the vaginal microbiota.

Imitating a stress response: a new hypothesis about the innate immune system's role in pregnancy

Recent research challenges long-held hypotheses about mechanisms through which pregnancy induces maternal immune suppression or tolerance of the embryo/fetus. It is now understood that normal pregnancy engages the immune system and that the immune milieu changes with advancing gestation. We suggest that pregnancy mimics the innate immune system's response to stress, causing a sterile inflammatory response that is necessary for successful reproduction. The relationship between external stressors and immunomodulation in pregnancy has been acknowledged, but the specific mechanisms are still being explicated. Implantation and the first trimester are times of immune activation and intensive inflammation in the uterine environment. A period of immune quiescence during the second trimester allows for the growth and development of the maturing fetus. Labor is also an inflammatory event. The length of gestation and timing of parturition can be influenced by environmental stressors. These stressors affect pregnancy through neuroendocrine interaction with the immune system, specifically through the hypothalamic-pituitary-adrenal (HPA) axis and the hypothalamic-pituitary-ovarian axis. Trophoblastic cells that constitute the maternal-fetal interface appear to harness the maternal immune system to promote and maximize the reproductive success of the mother and fetus. Pregnancy is a time of upregulated innate immune responses and decreased adaptive, cell-mediated responses. The inflammatory processes of pregnancy resemble an immune response to brief naturalistic stressors: there is a shift from T helper (Th) 1 to T helper (Th) 2 dominant adaptive immunity with a concomitant shift in cytokine production, decreased proliferation of T cells, and decreased cytotoxicity of natural killer (NK) cells. Inclusion of both murine and human studies, allows an exploration of insights into how trophoblasts influence the activity of the maternal innate immune system during gestation.

The immune privilege of testis and gravid uterus: same difference?

The fetus in the gravid uterus and the developing spermatogenic cells in the adult testis both comprise special challenges for the host immune system. Protection of the neoantigens of the fetus and male germ cells from immune attack, defined as immune privilege, is fundamental for the propagation of species. Immune privilege is not simply the absence of leukocytes, but involves immune and non-immune cells acting synergistically together at multiple levels to create a unique tolerogenic environment. A number of the pathways are shared by the testis and gravid uterus. Amongst them steroid hormones, namely testosterone in the male and progesterone in the female, seem to function as key molecules that govern the local production of immunoregulatory factors which finally control the overall immune environment.

The impact of maternal anti-retroviral therapy on cytokine profile in the uninfected neonates

The number of HIV-infected young women has been increasing since the beginning of the AIDS epidemic. The objective of the present study was to investigate the impact of anti-retroviral treatment (ART) of HIV-1-infected pregnant women (PW) on cytokine profile of uninfected neonates. Our results demonstrated that higher levels of IL-1β and TNF-α associated with lower IL-10 production were detected in the plasma obtained from neonates born from ART-treated PW. Furthermore, the production of TNF- α and IFN-γ was also significantly higher in polyclonally-activated T cells from those neonates. This elevated pro-inflammatory pattern detected by these activated-T cells was not associated to HIV-1 antigens sensitization. Finally, ART-exposed neonates showed to be born with lower weight, and it was inversely correlated with maternal peripheral TNF-a level. In summary, the data presented here suggest a significant disturbance in cytokine network of HIV-1-uninfected neonates exposed to potent anti-retroviral schemes during pregnancy.

Future directions of studies for recurrent miscarriage associated with immune etiologies

A significant proportion of recurrent pregnancy loss (RPL) is associated with immune etiologies. The immunological environment is different between decidua basalis and decidua parietalis, and also different between RPL cases with normal fetal chromosomes and those with abnormal fetal chromosomes. Recent data show that the immune system in a late-stage abortion is completely different from that in an early-stage abortion. If immunocompetent cells can cause RPL, the immunological environment may be a causative factor, especially in an early-stage abortion, and/or at decidua basalis and/or in the cases of RPL with a normal embryo. Careful examination of the immune system at the decidua basalis in an early-stage abortion in RPL cases with normal fetal chromosome may reveal useful information.

Inflammation and pregnancy: the role of the immune system at the implantation site

The concept that pregnancy is associated with immune suppression has created a myth of pregnancy as a state of immunological weakness and, therefore, of increased susceptibility to infectious diseases. A challenging question is whether the maternal immune system is a friend or a foe of pregnancy. In this review, we discuss data associated to the role of the immune system during pregnancy. We propose a new paradigm in terms of the fetal-maternal immune interaction as well as the immunological response of the mother to microorganism. Our challenge is to better understand the immunology of pregnancy in order to deliver the appropriate treatment to patients with pregnancy complications as well as to determine public policies for the protection of pregnant women during pandemics.

The immune system in pregnancy: a unique complexity

Placental immune response and its tropism for specific viruses and pathogens affect the outcome of the pregnant woman's susceptibility to and severity of certain infectious diseases. The generalization of pregnancy as a condition of immune suppression or increased risk is misleading and prevents the determination of adequate guidelines for treating pregnant women during pandemics. There is a need to evaluate the interaction of each specific pathogen with the fetal/placental unit and its responses to design the adequate prophylaxis or therapy. The complexity of the immunology of pregnancy and the focus, for many years, on the concept of immunology of pregnancy as an organ transplantation have complicated the field and delayed the development of new guidelines with clinical implications that could help to answer these and other relevant questions. Our challenge as scientists and clinicians interested in the field of reproductive immunology is to evaluate many of the 'classical concepts' to define new approaches for a better understanding of the immunology of pregnancy that will benefit mothers and fetuses in different clinical scenarios.

Comparison of murine thymic stromal lymphopoietin- and polyinosinic polycytidylic acid-mediated placental dendritic cell activation

We confirmed previously the existence of thymic stromal lymphopoietin (TSLP)-positive cells in murine placenta by flow cytometry. To compare the characteristics of Toll-like receptor 3 (TLR3)- and TSLP-mediated placental dendritic cell (DC) activation, pregnant BALB/c mouse mated with C57BL/6 male were used as a model of allogenic gestation. Placental CD11c(+) DCs were potently activated by the TLR3-agonist polyinosinic polycytidylic acid [poly (I:C)], subsequently causing increased expression of co-stimulatory molecules. Accordingly, increased intracellular production of interleukin (IL)-12 and interferon (IFN)-gamma, but not IL-4 or IL-10, were detected after stimulation by poly (I:C). In the case of TSLP-stimulation, although increased expression of co-stimulatory molecules was also detected, there was no substantial increase of intracellular production of IL-12, IFN-gamma, IL-4 or IL-10. In contrast, the expression of the Th2 cell-attracting chemokine, the thymus and activation-regulated chemokine (TARC) or CCL17, was significantly boosted in response to TSLP induction, whereas no significant increase of CCL17 was observed when triggering TLR3 with its specific agonist poly (I:C). The data were further supported by a CD4(+)IL-10(+) cell migratory assay. These results suggest that TSLP-TSLP receptor interaction may result in a Th2-type microenvironment at the feto-maternal interface by inducing the production of Th2 cell-attracting chemokine and modulating the immigration of Th2-type cells.

Altered immunological reactivity in HIV-1-exposed uninfected neonates

This work aimed to evaluate immune events in HIV-1-exposed uninfected neonates born from mothers who control (G1) or not (G2) the plasma viral load, using unexposed neonates as controls. Cord blood from each neonate was collected, plasma and mononuclear cells were separated and the lymphoproliferation and cytokine pattern were evaluated. The results demonstrated that the in vitro lymphoproliferation induced by polyclonal activators was higher in the G2 neonates. Nevertheless, no cell culture responded to poll synthetic HIV-1 envelope peptides. The cytokine dosage in the plasma and supernatants of polyclonally-activated cultures demonstrated that, while IL-4 and IL-10 were the dominant cytokines produced in G1 and control groups, IFN-gamma and TNF-alpha were significantly higher in G2 neonates. Systemic levels of IL-10 observed among the G1 neonates were higher in those born from anti-retroviral treated mothers. In summary, our results indicate an altered immune responsiveness in neonates exposed in utero to HIV and support the role of maternal anti-retroviral treatment to attenuate it.