A Rare Case of Hemolytic Disease of the Fetus and Newborn Caused by Anti-s Antibody in a Chinese Patient.

BACKGROUND: Anti-s is a rare alloantibody, and the reported cases of hemolytic disease of the fetus and newborn (HDFN) caused by anti-s are limited to non-Asian populations. METHODS: Here, we report the case of a Chinese woman with a history of multiple pregnancies who developed an alloantibody with anti-s specificity. RESULTS: Her newborn developed HDFN caused by anti-s but the clinical symptoms were not serious. After supportive treatment and bilirubin light phototherapy, the baby was discharged with a good prognosis. CONCLUSIONS: This is the first reported case of anti-s-induced HDFN in a Chinese patient, highlighting the need for further research in the Asian population.

Prebiotic Supplementation During Pregnancy Modifies the Gut Microbiota and Increases Metabolites in Amniotic Fluid, Driving a Tolerogenic Environment In Utero.

The gut microbiota is influenced by environmental factors such as food. Maternal diet during pregnancy modifies the gut microbiota composition and function, leading to the production of specific compounds that are transferred to the fetus and enhance the ontogeny and maturation of the immune system. Prebiotics are fermented by gut bacteria, leading to the release of short-chain fatty acids that can specifically interact with the immune system, inducing a switch toward tolerogenic populations and therefore conferring health benefits. In this study, pregnant BALB/cJRj mice were fed either a control diet or a diet enriched in prebiotics (Galacto-oligosaccharides/Inulin). We hypothesized that galacto-oligosaccharides/inulin supplementation during gestation could modify the maternal microbiota, favoring healthy immune imprinting in the fetus. Galacto-oligosaccharides/inulin supplementation during gestation increases the abundance of Bacteroidetes and decreases that of Firmicutes in the gut microbiota, leading to increased production of fecal acetate, which was found for the first time in amniotic fluid. Prebiotic supplementation increased the abundance of regulatory B and T cells in gestational tissues and in the fetus. Interestingly, these regulatory cells remained later in life. In conclusion, prebiotic supplementation during pregnancy leads to the transmission of specific microbial and immune factors from mother to child, allowing the establishment of tolerogenic immune imprinting in the fetus that may be beneficial for infant health outcomes.

Decreased maternal serum acetate and impaired fetal thymic and regulatory T cell development in preeclampsia.

Maternal immune dysregulation seems to affect fetal or postnatal immune development. Preeclampsia is a pregnancy-associated disorder with an immune basis and is linked to atopic disorders in offspring. Here we show reduction of fetal thymic size, altered thymic architecture and reduced fetal thymic regulatory T (Treg) cell output in preeclamptic pregnancies, which persists up to 4 years of age in human offspring. In germ-free mice, fetal thymic CD4+ T cell and Treg cell development are compromised, but rescued by maternal supplementation with the intestinal bacterial metabolite short chain fatty acid (SCFA) acetate, which induces upregulation of the autoimmune regulator (AIRE), known to contribute to Treg cell generation. In our human cohorts, low maternal serum acetate is associated with subsequent preeclampsia, and correlates with serum acetate in the fetus. These findings suggest a potential role of acetate in the pathogenesis of preeclampsia and immune development in offspring.

Continuous Anti-TNFα Use Throughout Pregnancy: Possible Complications For the Mother But Not for the Fetus. A Retrospective Cohort on the French National Health Insurance Database (EVASION).

OBJECTIVES: Inflammatory bowel diseases (IBD) need long-term treatment, which can influence pregnancies in young women. Uncontrolled IBD is associated with poor pregnancy outcomes. Despite the labeling of Anti-tumor necrosis factor (TNF) antibodies (anti-TNFα) which indicates that their use is not recommended during pregnancy, anti-TNFα are increasingly being used during pregnancy and may expose women and their fetuses to treatment-related complications. Existing recommendations on the timing of treatment during pregnancy are inconsistent. We aimed to assess the safety of anti-TNFα treatment in pregnant women with IBD, and up to the first year of life for their children. METHODS: An exposed/non exposed retrospective cohort was conducted on the French national health system database SNIIRAM (Système National d'Information Inter-Régimes de l'Assurance Maladie). All IBD women who became pregnant between 2011 and 2014 were included. Women with concomitant diseases potentially treated with anti-TNFα were excluded. Anti-TNFα exposure (infliximab, adalimumab, golimumab or certolizumab pegol) during pregnancy was retrieved from the exhaustive prescription database in SNIIRAM. The main judgment criterion was a composite outcome of disease-, treatment- and pregnancy-related complications during pregnancy for the mother, and infections during the first year of life for children. RESULTS: We analyzed data from 11,275 pregnancies (8726 women with IBD), among which 1457 (12.9%) pregnancies were exposed to anti-TNFα, mainly infliximab or adalimumab, with 1313/7722 (17.0%) suffering from Crohn's disease and 144/3553 (4.1%) from ulcerative colitis. After adjusting for disease severity, steroid use, age, IBD type, and duration and concomitant 6-mercaptopurine use, anti-TNFα treatment was associated with a higher risk of overall maternal complications (adjusted Odds Ratio (aOR) = 1.49; 95% confidence interval (CI): 1.31-1.67) and infections (aOR = 1.31; 95% CI: 1.16-1.47). Maintaining anti-TNFα after 24 weeks did not increase the risk of maternal complication, but interrupting the anti-TNFα increased relapse risk. No increased risk for infection was found in children (aOR = 0.89; 95% CI: 0.76-1.05) born to mother exposed to anti-TNFα during pregnancy. CONCLUSIONS: Anti-TNFα treatment during pregnancy increased the risk of maternal complications compared to unexposed; however, discontinuation before week 24 increased the risk of disease flare. There was no increased risk for children exposed to anti-TNFα up to 1 year of life.

Maternal pomegranate juice attenuates maternal inflammation-induced fetal brain injury by inhibition of apoptosis, neuronal nitric oxide synthase, and NF-κB in a rat model.

BACKGROUND: Maternal inflammation is a risk factor for neonatal brain injury and future neurological deficits. Pomegranates have been shown to exhibit anti-inflammatory, anti-apoptotic and anti-oxidant activities. OBJECTIVE: We hypothesized that pomegranate juice (POM) may attenuate fetal brain injury in a rat model of maternal inflammation. STUDY DESIGN: Pregnant rats (24 total) were randomized for intraperitoneal lipopolysaccharide (100 µg/kg) or saline at time 0 at 18 days of gestation. From day 11 of gestation, 12 dams were provided ad libitum access to drinking water, and 12 dams were provided ad libitum access to drinking water with pomegranate juice (5 mL per day), resulting in 4 groups of 6 dams (saline/saline, pomegranate juice/saline, saline/lipopolysaccharide, pomegranate juice/lipopolysaccharide). All dams were sacrificed 4 hours following the injection and maternal blood and fetal brains were collected from the 4 treatment groups. Maternal interleukin-6 serum levels and fetal brain caspase 3 active form, nuclear factor-κB p65, neuronal nitric oxide synthase (phosphoneuronal nitric oxide synthase), and proinflammatory cytokine levels were determined by enzyme-linked immunosorbent assay and Western blot. RESULTS: Maternal lipopolysaccharide significantly increased maternal serum interleukin-6 levels (6039 ± 1039 vs 66 ± 46 pg/mL; P < .05) and fetal brain caspase 3 active form, nuclear factor-κB p65, phosphoneuronal nitric oxide synthase, and the proinflammatory cytokines compared to the control group (caspase 3 active form 0.26 ± 0.01 vs 0.20 ± 0.01 U; nuclear factor-κB p65 0.24 ± 0.01 vs 0.1 ± 0.01 U; phosphoneuronal nitric oxide synthase 0.23 ± 0.01 vs 0.11 ± 0.01 U; interleukin-6 0.25 ± 0.01 vs 0.09 ± 0.01 U; tumor necrosis factor-α 0.26 ± 0.01 vs 0.12 ± 0.01 U; chemokine (C-C motif) ligand 2 0.23 ± 0.01 vs 0.1 ± 0.01 U). Maternal supplementation of pomegranate juice to lipopolysaccharide-exposed dams (pomegranate juice/lipopolysaccharide) significantly reduced maternal serum interleukin-6 levels (3059 ± 1121 pg/mL, fetal brain: caspase 3 active form (0.2 ± 0.01 U), nuclear factor-κB p65 (0.22 ± 0.01 U), phosphoneuronal nitric oxide synthase (0.19 ± 0.01 U) as well as the brain proinflammatory cytokines (interleukin-6, tumor necrosis factor-α and chemokine [C-C motif] ligand 2) compared to lipopolysaccharide group. CONCLUSION: Maternal pomegranate juice supplementation may attenuate maternal inflammation-induced fetal brain injury. Pomegranate juice neuroprotective effects might be secondary to the suppression of both the maternal inflammatory response and inhibition of fetal brain apoptosis, neuronal nitric oxide synthase, and nuclear factor-κB activation.

Anti-M induced severe haemolytic disease of foetus and newborn in a Malay woman with recurrent pregnancy loss.

Haemolytic disease of the foetus and newborn (HDFN) is caused by maternal red blood cells (RBC) alloimmunisation resulted from incompatibility of maternal and foetal RBCs. However, only a few HDFN attributed to anti-M were reported, varying from asymptomatic to severe anaemia with hydrops foetalis and even intrauterine death. A case of severe HDFN due to anti-M alloantibody from an alloimmunized grandmultiparous Malay woman with recurrent pregnancy loss is reported here. The newborn was delivered with severe and prolonged anaemia which required frequent RBC transfusions, intensive phototherapy and intravenous immunoglobulin administration. Although anti-M is rarely known to cause severe HDFN, a careful serological work-up and close assessment of foetal well-being is important, similar to the management of RhD HDFN. Alloimmunisation with anti-M type can lead to severe HDFN and even foetal loss.

Safety evaluation of a vaccine: Effect in maternal reproductive outcome and fetal anomaly frequency in rats using a leishmanial vaccine as a model.

While the immunogenic potential of the vaccination against infectious diseases was extensively shown, data on the safety assessment of recombinant proteins in vaccine formulations administered during pregnancy are still scarce. In the current study, the antigenicity of a vaccine against leishmaniasis (based on Leishmania braziliensis recombinant protein peroxidoxin) during pregnancy and possible maternal reproductive outcomes and fetal anomalies after immunization with a leishmanial vaccine or adjuvant alone (Bordetella pertussis derived MPLA adjuvant) were assessed. Rats were mated and allocated in three groups: Control-rats received saline; Adjuvant-rats received the adjuvant MPLA, and Vaccine-rats received the combination of MPLA and peroxidoxin. The administration was subcutaneously at the dorsal region, three times (days 0, 7, 14 of pregnancy). On day 21 of pregnancy, all rats were bled for biochemical and immunological measurements. The gravid uterus was weighed with its contents, and the fetuses were analyzed. The immunization with peroxidoxin induced a significant production of circulating IgG levels compared to other groups but caused a significant in post-implantation loss (14.7%) when compared to Control (5.0%) and Adjuvant (4.4%) groups. Furthermore, a significantly high rate of fetal visceral anomalies, such as hydronephrosis and convoluted ureter, was also observed in animals that received vaccine when compared to Control or Adjuvant groups. These data indicate the importance of safety evaluation of vaccines during pregnancy and the limited use of peroxidoxin administration during pregnancy. More importantly, the safety monitoring of immunization with MPLA derived from Bordetella pertussis demonstrated no reproductive outcomes associated with adjuvant administration, suggesting its safe use during pregnancy.

Progesterone and HMOX-1 promote fetal growth by CD8+ T cell modulation.

Intrauterine growth restriction (IUGR) affects up to 10% of pregnancies in Western societies. IUGR is a strong predictor of reduced short-term neonatal survival and impairs long-term health in children. Placental insufficiency is often associated with IUGR; however, the molecular mechanisms involved in the pathogenesis of placental insufficiency and IUGR are largely unknown. Here, we developed a mouse model of fetal-growth restriction and placental insufficiency that is induced by a midgestational stress challenge. Compared with control animals, pregnant dams subjected to gestational stress exhibited reduced progesterone levels and placental heme oxygenase 1 (Hmox1) expression and increased methylation at distinct regions of the placental Hmox1 promoter. These stress-triggered changes were accompanied by an altered CD8+ T cell response, as evidenced by a reduction of tolerogenic CD8+CD122+ T cells and an increase of cytotoxic CD8+ T cells. Using progesterone receptor- or Hmox1-deficient mice, we identified progesterone as an upstream modulator of placental Hmox1 expression. Supplementation of progesterone or depletion of CD8+ T cells revealed that progesterone suppresses CD8+ T cell cytotoxicity, whereas the generation of CD8+CD122+ T cells is supported by Hmox1 and ameliorates fetal-growth restriction in Hmox1 deficiency. These observations in mice could promote the identification of pregnancies at risk for IUGR and the generation of clinical interventional strategies.

Vitamin D hormone regulates serotonin synthesis. Part 1: relevance for autism.

Serotonin and vitamin D have been proposed to play a role in autism; however, no causal mechanism has been established. Here, we present evidence that vitamin D hormone (calcitriol) activates the transcription of the serotonin-synthesizing gene tryptophan hydroxylase 2 (TPH2) in the brain at a vitamin D response element (VDRE) and represses the transcription of TPH1 in tissues outside the blood-brain barrier at a distinct VDRE. The proposed mechanism explains 4 major characteristics associated with autism: the low concentrations of serotonin in the brain and its elevated concentrations in tissues outside the blood-brain barrier; the low concentrations of the vitamin D hormone precursor 25-hydroxyvitamin D [25(OH)D3]; the high male prevalence of autism; and the presence of maternal antibodies against fetal brain tissue. Two peptide hormones, oxytocin and vasopressin, are also associated with autism and genes encoding the oxytocin-neurophysin I preproprotein, the oxytocin receptor, and the arginine vasopressin receptor contain VDREs for activation. Supplementation with vitamin D and tryptophan is a practical and affordable solution to help prevent autism and possibly ameliorate some symptoms of the disorder.

Surfactant protein (SP)-A suppresses preterm delivery and inflammation via TLR2.

Toll like receptors (TLRs) are pattern-recognition molecules that initiate the innate immune response to pathogens. Pulmonary surfactant protein (SP)-A is an endogenously produced ligand for TLR2 and TLR4. SP-A has been proposed as a fetally produced signal for the onset of parturition in the mouse. We examined the effect of interactions between SP-A and the pathogenic TLR agonists lipopolysaccharide (LPS), peptidoglycan (PGN) and polyinosinic:cytidylic acid (poly(I:C)) (ligands for TLR4, TLR2 and TLR3, respectively) on the expression of inflammatory mediators and preterm delivery. Three types of mouse macrophages (the cell line RAW 264.7, and fresh amniotic fluid and peritoneal macrophages, including macrophages from TLR4 and TLR2 knockout mice) were treated for up to 7 hours with pathogenic TLR agonists with or without SP-A. SP-A alone had no effect upon inflammatory mediators in mouse macrophages and did not independently induce preterm labor. SP-A significantly suppressed TLR ligand-induced expression of inflammatory mediators (interleukin (IL)-1ß, tumor necrosis factor (TNF)-α and the chemokine CCL5) via a TLR2 dependent mechanism. In a mouse inflammation-induced preterm delivery model, intrauterine administration of SP-A significantly inhibited preterm delivery, suppressed the expression of proinflammatory mediators and enhanced the expression of the CXCL1 and anti-inflammatory mediator IL-10. We conclude that SP-A acts via TLR2 to suppress TLR ligand-induced preterm delivery and inflammatory responses.

Maternal N-acetyl-cysteine (NAC) protects the rat fetal brain from inflammatory cytokine responses to lipopolysaccharide (LPS).

OBJECTIVE: Inflammatory cytokines, play a central role in the genesis of preterm parturition and fetal brain injury. Lipopolysaccharide (LPS) may activate cytokine pathways via induction of oxidative stress pathways. We hypothesized that enhanced maternal antioxidant activity may blunt fetal brain inflammatory responses to maternal LPS injection in pregnant rats. METHODS: Pregnant Sprague-Dawley rats at 18 and 20 days gestation received intraperitoneal (ip) LPS injection and pre- and post-treatment with the antioxidant N-acetyl-cysteine (NAC) or saline. Six hours after the LPS injection, rats were sacrificed, interleukin (IL)-6 and IL-10 mRNA expression in the fetal brains was determined by real time polymerase chain reaction. RESULTS: Maternal ip LPS induced significant increase in fetal brain IL-6 mRNA expression at E18 (3.1 ± 0.6 vs 1.0 ± 0.10 AU) and E20 (29.01 + 13.06 vs 0.95 + 0.05 AU; p < 0.05) compared to Control, only at E20 maternal LPS induced increase in fetal brain IL-10 compared to control. NAC administered prior to and after LPS significantly reduced fetal brain IL-6 at E18 and E20 and IL-10 at E20. CONCLUSION: Maternal NAC can protect the fetal brain from inflammatory cytokine responses to maternal LPS injection. These results suggest that NAC may potentially protect fetus from inflammation-associated brain injury and potential long term sequelae.

Fetal intraperitoneal injection of immunoglobulin diminishes alloimmune hemolysis.

We report a case of severe fetal anemia associated with maternal anti-M antibody that was treated by direct injection of pooled human immunoglobulin into the fetal abdominal cavity. Four treatments at a dosage of 2 g per-kg estimated fetal body weight were performed, and no side effects were observed. A healthy baby girl was delivered transvaginally at 38 weeks, with neither exchange transfusion nor phototherapy required. Follow-up over 12 months found no indications of anemia or developmental delay in the child. This is believed to be the first report of fetal anemia in a blood-type-incompatible pregnancy being treated successfully with only direct immunoglobulin injection into the fetus. The immunoglobulin may have functioned as a neutralizing antibody causing the anemia to improve.

A review of immune transfer by the placenta.

Feto-maternal immune transfer occurs via both the placenta in utero and colostrum after birth. The layers between the maternal and fetal circulation systems, known as the placental barrier, regulate immune transfer to the fetus via the placenta. The placental barrier, as well as the type of placental structure, is species specific. The extent of transfer of antibodies from mother to fetus is related to the number of placental barrier layers. Passive immunity via the colostrum is essential in species in which the type of placentation impedes contact between maternal and fetal circulation systems, hindering the transfer of antibodies. In these species, susceptibility to neonatal infections is increased if colostrum is not ingested. Acquired antibodies are of extreme importance for adaptation of the neonate to the extrauterine environment. Based on the aforementioned factors, it was observed that in synepitheliochorial and epitheliochorial placentas immune transfer via the placenta is not possible, except in cases of placental alteration (e.g., placentitis). On the other hand, the mechanism of transfer in endothelial and hemochorial placentas is facilitated compared with other placentas. We conclude that there are no appreciable qualitative differences between the two mechanisms of transfer (placenta and colostrum) and that immune protection in the neonate can be attained by either mechanism.

Maternal diet during pregnancy has tissue-specific effects upon fetal fatty acid composition and alters fetal immune parameters.

Both animal and human studies demonstrate that the docosahexaenoic acid (DHA) content of plasma and/or tissue lipids is increased during pregnancy. We hypothesised that increasing the α-linolenic acid (ALA) or longer chain (n-3) PUFA content of the maternal diet during pregnancy influences fetal fatty acid composition and the fetal immune system. Pregnant rats were fed a low-fat (LF) soybean oil diet, or high-fat (HF) soybean, linseed, salmon or sunflower oil diets from conception to 20d gestation. The ALA-rich Linseed-HF diet resulted in an equivalent eicosapentaenoic acid (EPA) status in fetal immune tissues and an equivalent DHA status in the fetal brain to that achieved with the Salmon-HF diet. An (n-3) rich maternal diet during pregnancy associated with the highest expression of CD3 (Salmon-HF) and CD8 (Linseed-HF and Salmon-HF) on fetal thymic CD3(+)CD8(+) cells. The Linseed-HF diet resulted in the highest proportion of CD161(+) cells within the fetal thymus, which correlated with the production of IL-4. These data indicate that dietary ALA supplementation may confer some of the benefits of LC (n-3) PUFA during pregnancy. This should be examined in suitably designed human studies.

Effects of galactooligosaccharide and long-chain fructooligosaccharide supplementation during pregnancy on maternal and neonatal microbiota and immunity--a randomized, double-blind, placebo-controlled study.

BACKGROUND: Galactooligosaccharides (GOS) and long-chain fructooligosaccharides (lcFOS) proliferate bifidobacteria in infant gut microbiota. However, it is not known how GOS and FOS influence the microbiota of pregnant women and whether a potential prebiotic effect is transferred to the offspring. OBJECTIVES: We aimed to test how supplementation with GOS and lcFOS (GOS/lcFOS) in the last trimester of pregnancy affects maternal and neonatal gut microbiota. Variables of fetal immunity were assessed as a secondary outcome. DESIGN: In a randomized, double-blind, placebo-controlled pilot study, 48 pregnant women were supplemented 3 times/d with 3 g GOS/lcFOS (at a ratio of 9:1) or maltodextrin (placebo) from week 25 of gestation until delivery. Percentages of bifidobacteria and lactobacilli within total bacterial counts were detected by fluorescent in situ hybridization and quantitative polymerase chain reaction in maternal and neonatal (days 5, 20, and approximately 182) stool samples. Variables of fetal immunity were assessed in cord blood by using flow cytometry and cytokine multiplex-array analysis. RESULTS: The proportions of bifidobacteria in the maternal gut were significantly higher in the supplemented group than in the placebo group (21.0% and 12.4%, respectively; P = 0.026); the proportion of lactobacilli did not differ between the groups. In neonates, bifidobacteria and lactobacilli percentages, diversity and similarity indexes, and fetal immune parameters did not differ significantly between the 2 groups. Mother-neonate similarity indexes of bifidobacteria decreased over time. CONCLUSIONS: GOS/lcFOS supplementation has a bifidogenic effect on maternal gut microbiota that is not transferred to neonates. The increased maternal bifidobacteria did not affect fetal immunity as measured by a comprehensive examination of cord blood immunity variables.

Hypothalamic control of mitogen-induced proliferative responses and luteinizing hormone-releasing hormone levels in thymus and peripheral blood of rat fetuses.

The role of endogenous luteinizing hormone-releasing hormone (LHRH) in the development of concanavalin A (ConA)-induced proliferative responses was studied in rat fetuses. Preliminary treatment of fetuses in utero with either the LHRH receptor antagonist or anti-LHRH antibodies resulted in the suppression of ConA-induced proliferative responses of thymocytes. LHRH and LHRH-immunopositive cells, morphologically similar to thymocytes, were detected in intact fetal thymus. A significant content of LHRH was also found in the peripheral blood of fetuses. The LHRH content in thymus and plasma was similar in males and females. Surgical ablation of the hypothalamus resulted in 2-fold decreases in thymus and plasma levels of LHRH in 21-day-old fetuses compared to sham-operated fetuses. It was concluded that LHRH regulates mitogen-induced proliferative responses of thymocytes during prenatal ontogenesis in the rat. The main source of plasma LHRH at that period is the hypothalamus. Moreover, LHRH is synthesized in the fetal thymus. Thus, LHRH is suggested to have not only a central effect but also to be involved in autocrine or paracrine regulation of proliferative immune responses.

Critical periods of special health relevance for psychoneuroimmunology.

Although it is possible to demonstrate an influence of psychological factors on immune responses at any point in the life span, there are two periods when the effects may have greater implications for health. Our research with nonhuman primates indicates that the immaturity of a young infant's immune responses makes it more vulnerable, especially during the fetal and neonatal stages. Similarly, the natural, age-related process of immune senescence creates a second period of increased risk in elderly animals and people. This review summarizes findings from a 20-year research program, which support the conclusion that we should give special attention to the age of the host in psychoneuroimmunology studies.

In utero development of a warm-reactive autoantibody in a severely jaundiced neonate.

BACKGROUND: The fetus and neonate are widely considered to be immunologically immature. However, there are rare case reports of RBC alloantibody and autoantibody development. STUDY DESIGN AND METHODS: This report describes the case of a severely jaundiced full-term boy neonate presenting at birth with an IgG warm-reactive autoantibody. RESULTS: Mother and neonate were both blood group A, D+. The mother had a negative antibody screen at 18 weeks' gestation and a negative DAT and antibody screen at the time of delivery. The neonate was born with a strongly reactive DAT (IgG) and a panreactive eluate. The serum also contained a panreactive antibody, and all crossmatches were incompatible. The neonate had a bilirubin of 12.5 mg per dL at birth, which peaked at 22.5 mg per dL. However, there was no overt evidence of hemolysis, as evidenced by normal serial Hct levels and reticulocyte counts. The neonate responded well to phototherapy and did not require either simple or exchange transfusion. The neonate's warm-reactive autoantibody maintained its original strength of reactivity on follow-up testing performed at 2 weeks and 2 months of age. CONCLUSIONS: This report describes a rare case of apparent in utero RBC autoantibody development. The fetal/neonatal immune response to blood group antigens is reviewed.

Bovine neonatal immunology.

The majority of early, in utero immune development occurs independent of antigen exposure. Only later during development can a fetus respond to antigens, and even then the response depends on the stage of fetal development and the nature of the antigen. At birth, the neonate is rapidly exposed to large numbers of potential pathogens. Although immunocompetent, the neonate is immunonaive and dependent on passively acquired maternal immunoglobulins, immune cells, and other substances from colostrum for protection. Neonates that suffer failure of passive transfer of maternal immunoglobulins may be at increased risk for disease; however, many other factors interact in conjunction with the level of passively acquired immunoglobulin to determine the occurrence of disease. These include, but are not limited to, management, environment, hygiene, infection pressure, virulence of organisms, and antibody specificity. In addition to immunoglobulins, colostrum contains large numbers of immune cells and cytokines. It is thought that the primary role for the cellular component of colostrum is to interact with the development of local immunity and to modulate active immunization of the neonatal intestine. In particular, T lymphocytes are thought to transfer immune functions and secrete cytokines. Although most of the major cytokines have been identified in colostrum and milk, their biologic effects on the neonate have yet to be determined.