Fetal Mononuclear Cells Research Articles

SARS-CoV2 vertical transmission with adverse effects on the newborn revealed through integrated immunohistochemical, electron microscopy and molecular analyses of Placenta.

Background. The occurrence of trans-placental transmission of severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) infection remains highly debated. Placental positivity for SARS-CoV-2 has been reported in selected cases, but infection or virus-associated disease of fetal tissues or newborns remains to be demonstrated.MethodsWe screened for SARS-CoV-2 spike (S) protein expression placentas from 101 women who delivered between February 7 and May 15, 2020, including 15 tested positive for SARS-CoV-2 RNA, 34 tested negative, and 52 not evaluated as they did not meet testing criteria (32), or delivered before COVID-19 pandemic declaration (20). Immunostain for SARS-CoV-2 nucleocapsid (N) was performed in the placentas of all COVID-19 positive women. One placenta resulted positive for the SARS-CoV-2 S and N proteins, which was further studied by RNA-in situ hybridization and RT-PCR for S transcripts, and by electron microscopy. A comprehensive immunohistochemical and immunofluorescence analysis of the placental inflammatory infiltrate completed the investigations.FindingsSARS-CoV-2 S and N proteins were strongly expressed in the placenta of a COVID-19 pregnant woman whose newborn tested positive for viral RNA and developed COVID-19 pneumonia soon after birth. SARS-CoV-2 antigens, RNA and/or particles morphologically consistent with coronavirus were identified in villous syncytiotrophoblast, endothelial cells, fibroblasts, in maternal macrophages, and in Hofbauer cells and fetal intravascular mononuclear cells. The placenta intervillous inflammatory infiltrate consisted of neutrophils and monocyte-macrophages expressing activation markers. Absence of villitis was associated with an increase in the number of Hofbauer cells, which expressed PD-L1. Scattered neutrophil extracellular traps (NETs) were identified by immunofluorescence.InterpretationWe provide first-time evidence for maternal-fetal transmission of SARS-CoV-2, likely propagated by circulating virus-infected fetal mononuclear cells. Placenta infection was associated with recruitment of maternal inflammatory cells in the intervillous space, without villitis. PD-L1 expression in syncytiotrophoblast and Hofbaeur cells, together with limited production of NETs, may have prevented immune cell-driven placental damage, ensuring sufficient maternal-fetus nutrient exchanges.

SARS-CoV-2 Vertical Transmission with Adverse Effects on the Newborn Revealed Through Integrated Immunohistochemical, Electron Microscopy and Molecular Analyses of Placenta

Background: The occurrence of trans-placental transmission of severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) infection remains highly debated. Placental positivity for SARS-CoV-2 has been reported in selected cases, but infection or virus-associated disease of fetal tissues or newborns remains to be demonstrated. Methods: We screened for SARS-CoV-2 spike (S) protein expression placentas from 101 women who delivered between February 7 and May 15 2020, including 15 tested positive for SARS-CoV-2 RNA, 34 tested negative, and 52 not evaluated as they did not meet testing criteria (32), or delivered before COVID-19 pandemic declaration (20). Immunostain for SARS-CoV-2 nucleocapside (N) was performed in the placentas of all COVID-19 positive women. The single placenta resulted positive for the SARS-Cov2 S and N proteins was further studied by RNA-in situ hybridization for S transcripts, RT-PCR RNA, and by electron microscopy. A detailed immunohistochemical and immunofluorescence analysis of the placental inflammatory infiltrate completed the investigations. Findings: SARS-CoV2 S and N proteins were strongly expressed in the placenta of a COVID-19 pregnant woman whose newborn tested positive for viral RNA and developed COVID-19 pneumonia soon after birth. SARS-CoV-2 antigens, RNA and/or viral particles were identified in villous syncytiotrophoblast, endothelial cells, fibroblasts, in maternal macrophages, and in Hofbauer cells and fetal intravascular mononuclear cells. The placenta intervillous inflammatory infiltrate was composed of neutrophils and monocyte-macrophages displaying activation markers. Absence of villitis was associated with an increase in the number of Hofbauer cells, which expressed PD-L1. Scattered neutrophil extracellular traps (NETs) were identified by immunofluorescence. Interpretation: We provide first-time evidence for maternal-fetal transmission of SARS-CoV-2, likely mediated by circulating virus-infected fetal mononuclear cells. Placenta infection was associated with recruitment of maternal inflammatory cells in the intervillous space, without villitis. PD-L1 expression in syncytiotrophoblast and Hofbaeur cells, together with limited production of NETs, may have prevented immune cell-driven placental damage, ensuring sufficient maternal-fetus exchanges. Funding Statement: None. Declaration of Interests: All authors declare no competing interests. Ethics Approval Statement: The study was reviewed and approved by the Institutional Ethical Board of Brescia Hospital (ASST Spedali Civili Brescia), protocol numbers: NP 4151- Study COVID-BIO (Multicentric observational prospective study on SARS-CoV-2 infection during pregnancy) and NP 4133- Study INTERCOVID (A prospective cohort study of the effects of COVID-19 in pregnancy and the neonatal period).

Comparsion between Intravenous Delivered Human Fetal Bone Marrow Mesenchymal Stromal Cells and Mononuclear Cells in the Treatment of Rat Cerebral Infarct.

Objective To compare the effecacy of human mesenchymal stromal cell (hMSC) with human mononuclear cell (hMNC) in treating rat cerebral infarct.Methods The SD rat models of cerebral infarct were established by distal middle cerebral artery occlusion (dMCAO). Rats were divided into four groups: sham,ischemia vehicle,MSC,and MNC transplantation groups. For the transplantation group,1×106 hMSCs or hMNCs were intravascularly transplanted into the tail vein 1 hour after the ischemia onset. The ischemia vehicle group received dMCAO surgery and intravascular saline injection 1,3,5,and 7 days after the ischemia onset,and then behavioral tests were performed. At 48 h after the ischemia onset,the abundance of Iba- 1,the symbol of activated microglia,was evaluated in the peri-ischemia striatum area; meanwhile,the neurotrophic factors such as glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF) in ipsilateral peri-ischemia striatum area were also measured. Results The relative infarct volume in ischemia vehicle group,hMSC group,and hMNC transplantation group were (37.85±4.40)%,(33.41±3.82)%,and (30.23±3.63)%,respectively. The infarct volumes of MSC group (t=2.100,P=0.034) and MNC group (t=2.109,P=0.0009) were significantly smaller than that of ischemia vehicle group,and that of MNC group was significantly smaller than that of MSC group (t=1.743,P=0.043). One day after transplantation,the score of ischemia vehicle group in limb placing test was (4.32±0.71)%,which was significantly lower than that in sham group (9.73±0.36)% (t=2.178,P=8.61×10-11). The scores of MSC and MNC group,which were (5.09±0.62)% (t=2.1009,P=0.024) and (5.90±0.68)% (t=2.1008,P=0.0001),respectively,were significantly higher than that of ischemia vehicle group; also,the score of MNC group was significantly higher than that of MSC group(t=2.1009,P=0.0165). The contralateral forelimb scores of MSC and MNC groups in beam walking test were (5.56±0.86)% (t=2.120,P=0.020) and (5.13±0.95)% (t=2.131,P=0.003),were both significantly lower than that of ischemia vehicle group [(6.47±0.61)%]. Three days after the transplantation,the limb placing test score of MNC group [(6.91±1.10)%] was significantly higher than that of ischemia vehicle group (5.80±0.82)% (t=2.110,P=0.027). The score of MSC group [(6.30±0.77)%] showed no statistic difference with that of ischemia vehicle group(t=2.101,P=0.199).The contralateral forelimb scores of MNC group in beam walking test [(4.34±0.58)%] was significantly lower than that of ischemia vehicle group [(5.31±0.65)%] (t=2.100,P=0.006) and MSC group [(4.92±0.53)%] (t=2.100,P=0.041); there was no statistic difference between MSC group and ischemia vehicle group (t=2.109,P=0.139). The relative abundance of Iba- 1 in sham,ischemia vehicle,MSC,and MNC groups was 1.00+0.00,1.72±0.21,1.23±0.08,and 1.48±0.06,respectively. The Iba-1 relative abundance of ischemia vehicle group was significantly higher than that of sham group (t=2.262,P=2.9×10-6). The Iba-1 relative abundances of both MSC (t=2.178,P=3.91×10-5)and MNC (t=2.200,P=0.007)groups were significantly lower than that of ischemia vehicle group. It was also significantly lower in MNC group than in MSC group also (t=2.120,P=7.09×10-6). Three days after transplantation,the BDNF and GDNF levels of MSC group,which were (531.127±73.176)pg/mg (t=2.109,P=0.003)and(127.780±16.733)pg/mg(t=2.100,P=2.76×10-5),respectively,were significantly higher than those of ischemia vehicle group,which were (401.988±89.006)pg/mg and (86.278±14.832) pg/mg,respectively. The BDNF and GDNF levels of MNC group,which were (627.429±65.646)pg/mg (t=2.144,P=0.017) and (153.117±20.443)pg/mg (t=2.109,P=0.010),respectively,were all significantly higher than that of MSC group. At day 7,the BDNF and GDNF levels of MSC group,which were (504.776±83.282)pg/mg (t=2.101,P=0.005) and (81.641±11.019)pg/mg (t=2.100,P=0.002),respectively,were significantly higher than those of ischemia vehicle group,which were (389.257±70.440)pg/mg and (64.322±9.855) pg/mg,respectively. The BDNF and GDNF levels of MNC group,which were (589.068±63.323)pg/mg (t=2.100,P=0.027) and (102.161±19.932)pg/mg (t=2.144,P=0.017),respectively,were all significantly higher than that of MSC group. Conclusions Both hMSC and hMNC are beneficial to the ischemia-damaged brain when they are intravascularly transplanted within 1 h after the onset of ischemia. The anti-inflammation ability and secretion of neurotrophic factors are the underlying mechanisms of the therapeutic effects. MNC is more effective than MSC in reducing infarct area and improving behaviors,which might be explained by the fact that MNC induces more GDNF and BDNF in brain than MSC.

Hypertension Editors’ Picks

<i>Hypertension</i> Editors’ Picks

Cellular Fetal Microchimerism in Preeclampsia

Previous studies have shown elevated concentrations of free fetal DNA and erythroblasts in maternal circulation in women with preeclampsia compared with those with normal pregnancy. Pluripotent and immunocompetent fetal cells also transfer to the maternal circulation during pregnancy, but whether concentrations of fetal mononuclear cells also differed in preeclampsia was unknown. We sought to quantify cellular fetal microchimerism in maternal circulation in women with preeclampsia and healthy controls. We studied women with preeclampsia and compared them with women with healthy pregnancies at similar gestational age. To identify a targetable polymorphism unique to the fetus to quantify fetal microchimerism, participants and family members were genotyped for the human leukocyte antigen loci DRB1, DQA1, and DQB1, as well as several other polymorphisms. A panel of polymorphism-specific quantitative polymerase chain reaction assays was used to identify and quantify fetal microchimerism in maternal peripheral blood mononuclear cells. Of 53 preeclampsia samples tested for cellular fetal microchimerism, 17 (32%) were positive when compared with 6 of 57 (6%) control samples (unadjusted odds ratio for detection, 4.0; 95% confidence interval, 1.5-11.1; P=0.007). The concentration of cellular fetal microchimerism (expressed as genome equivalents of fetal microchimerism per 100,000 maternal genome equivalents) was also higher among women with preeclampsia: median 0.0, mean 5.7, range 0 to 153.7, compared with those with controls: median 0.0, mean 0.3, range 0 to 9.1, P=0.002. We conclude that women with preeclampsia harbor cellular fetal microchimerism more commonly and at higher concentrations compared with women with uncomplicated pregnancy. The functional capacity and phenotype of these fetal cells are not yet known.

Co-ordinate expression of Th1/Th2 phenotypes in maternal and fetal blood: evidence for a transplacental nexus

If maternal atopy and environmental exposure affect prenatal Th cell development, the maternal and fetal immune systems should display common Th1/Th2 phenotypes. To test this hypothesis, we studied maternal and neonatal blood samples from mothers with total serum IgE <300 IU/mL. Basal levels of IFN-γ, IL-4, and eotaxin in paired maternal and fetal sera were tightly correlated. Polyclonal T cell activation in vitro by Staphylococcal exotoxin B induced co-ordinate IFN-γ production from paired maternal and fetal mononuclear cells, accompanied by co-ordinate increases in activated CD4+CD69+ cells that display the CCR4+Th2 and CXCR3+ Th1 phenotypes. Maternal and fetal CD4+CXCR3+ T cells were subsequently identified as the major producers of IFN-γ. The data established that a transplacental nexus exists during normal pregnancy and that fetal Th cell responses may be biased by the maternal immune system.

Evaluation of the Expression of Isoforms of Stem Cell Factor mRNA in Fetal Tissues and Mononuclear Cells at Different Stages of Human Development

We studied the expression of isoforms of stem cells factor mRNA forming as a result of alternative splicing. Both isoforms of stem cell factor mRNA forming as a result of alternative splicing were found in different fetal tissues. Changes in the expression of alternative isoforms of stem cell factor in peripheral blood mononuclear cells were demonstrated from the prenatal and neonatal periods to adult organism.

Abstract 2548: P57Kip2 restrains the stress response of hematopoietic stem cells and its absence leads to chemotherapy resistance

Abstract The cyclin-dependent kinase inhibitor P57Kip2 (Cdkn1c, p57) is a tumor suppressor gene with strong differential expression in both human and murine hematopoietic stem cells (HSC). P57 serves essential roles during embryogenesis, functioning in tissue-specific developmental programs to coordinate proliferation, differentiation and apoptosis. We have identified P57 as an early transcriptional target of the tumor suppressor TGFβ which is required for TGFβ-induced cytostasis of human CD34+ hematopoietic progenitor/stem cells; functions that provide a mechanistic basis for its expression being silenced in many aggressive human myeloid and lymphoid malignancies. To understand the role of P57 in HSC function, we used an engineered mouse strain deficient in P57. Using limiting-dilution HSC transplantation, the gold-standard assay with which to enumerate HSCs, we found that the fetal livers of p57-null mice have ∼4-fold fewer HSCs than their wild-type littermate controls. When we transplanted wt recipient mice with a mixture of p57-wt and p57-null fetal liver mononuclear cells (FLMC), we found that the p57-null hematopoietic cells were underrepresented in the blood of the recipient animals at steady-state. Both the limiting-dilution and competitive repopulation experiments indicate that the absence of p57 compromises HSC development. Strikingly, despite this quantitative deficit, we found that p57-null HSCs are qualitatively superior to p57-wt HSCs. Using serial transplantation, an assay of in vivo HSC self-renewal, we found that p57-null HSCs can be transplanted for two generations beyond which p57-wt HSCs are exhausted and unable to reconstitute hematopoiesis in the recipient animals. This result demonstrates under the tonic strain of serial transplantation, p57 normally serves to restrain HSC self-renewal. Importantly, mice with p57-null hematopoiesis are less sensitive to myelotoxic stress induced by the chemotherapeutics, 5-Fluorouracil (5FU) and cytarabine and have a shallower and shorter nadir following such treatment. Mice with p57-null hematopoiesis also recovered more briskly to the haemolytic agent phenylhydrazine suggesting that p57 serves a critical function restraining the stress-response of hematopoisis. When we administered 5FU to mice transplanted with mixtures of p57-null and p57-wt HSCs, we found that p57-null hematopoiesis contributed disproportionately to hematopoietic recovery and that this enhanced competition was durable. In composite, our findings reveal a novel role of p57 to restrain HSC self-renewal during periods of hematopoietic stress. These results suggest that cells deficient in p57 have an advantage over p57-expressing cells only after hematopoietic stress suggesting that silenced p57 expression can serve to promote malignant hematopoiesis at the expense of normal hematopoiesis and may contribute to chemotherapy resistance. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2548.

Progesterone suppresses the fetal inflammatory response ex vivo

Progesterone supplementation has been shown to be efficacious in preventing preterm birth. We sought to investigate the effects of progesterone on fetal inflammatory responses. Fetal mononuclear cells were isolated from umbilical cord blood and exposed to vehicle or progesterone (P4) for 1 hour prior to lipopolysaccharide (LPS) stimulation. Supernatants were assayed for tumor necrosis factor-alpha. Similar experiments were performed using cyclic adenosine monophosphate (cAMP) and progesterone modulators. The effect of P4 treatment on intracellular cAMP levels was also determined. LPS treatment led to a significant increase in cytokine production by fetal mononuclear cells. Despite the lack of detectable nuclear progesterone receptors, P4 suppressed this inflammatory response. R5020 (progesterone agonist), forskolin (cAMP inducer), and dibutyryl cAMP (cAMP agonist) all achieved immunosuppression. The cAMP antagonist, Rp-cAMP, blocked the inhibitory effect of progesterone. P4 significantly increased intracellular cAMP levels. Progesterone rapidly suppresses the fetal inflammatory response, possibly via nongenomic activation of the cAMP cascade.

Ontogenetic Features of the Expression of mRNA Isoforms for Leukemia-Inhibitory Factor in Human Fetal Tissues and Mononuclear Cells

The expression of leukemia-inhibitory factor mRNA in human fetal tissues and mononuclear cells was studied during ontogeny. The expression of mRNA isoforms for leukemia-inhibitory factor was tissue-specific at the stage of prenatal development. The transition from antenatal and neonatal development to the postnatal period was accompanied by a decrease in the expression of mRNA isoforms for leukemia-inhibitory factor in mononuclear cells.

635: 17-Hydroxyprogesterone caproate inhibits lipoteichoic acid and lipopolysaccharide induced secretion of IL-6 in fetal mononuclear cells but potentiates the IL-6 response of maternal mononuclear cells

635: 17-Hydroxyprogesterone caproate inhibits lipoteichoic acid and lipopolysaccharide induced secretion of IL-6 in fetal mononuclear cells but potentiates the IL-6 response of maternal mononuclear cells

Effects of early cigarette smoke exposure on early immune development and respiratory disease

Exposure to tobacco constituents during early development remains a common but avoidable toxic exposure, which has been clearly linked with decreased lung growth and subsequent wheezing illness. There is also now emerging evidence that tobacco smoke can influence early immune function. This includes alterations in cytokine production by the fetoplacental unit, as detected ex vivo in cord blood, as well as in patterns of fetal mononuclear cell responses in vitro. Recent studies also suggest that the newborns of smoking mothers have altered signalling through Toll-like receptors (TLRs) that are essential for innate microbial responses. This may be implicated in the increased predisposition to infection in exposed infants. TLR-mediated innate response pathways are also believed to be important in promoting regulatory pathways that inhibit allergic immune responses. However, although a number of studies have documented associations between early cigarette smoke exposure and subsequent allergic disease, this remains controversial. This review explores the consequences of smoking on these important aspects of early development, including potential mechanisms, interactions with predisposing asthma genes and a potential role in epigenetic regulation. Although parental smoking may not be the primary factor in the changing prevalence of asthma and respiratory disease, we propose that it is an important contributor, with significant potential to interact with other genetic factors and environmental risk factors to influence disease propensity.

414: Progesterone effect on lipoteichoic acid (LTA) induced secretion secretion of IL-6 in maternal and fetal mononuclear cells

414: Progesterone effect on lipoteichoic acid (LTA) induced secretion secretion of IL-6 in maternal and fetal mononuclear cells

Response of isolated monocytes and lymphocytes to LPS and progesterone

PROGESTERONE JENNIFER GOTKIN, JEREMY CELVER, PATRICK MCNUTT, SHAD DEERING, BOBBY HOWARD, NATHAN HOELDTKE, PETER NAPOLITANO, Madigan Army Medical Center, Maternal Fetal Medicine, Tacoma, Washington, Tripler Army Medical Center, Maternal Fetal Medicine, Honolulu, Hawaii OBJECTIVE: The mechanisms of progesterone action in the prevention of preterm labor are largely unknown but may result from its anti-inflammatory properties. We previously demonstrated that progesterone (P4) can inhibit lipopolysacharide (LPS) induced interleukin-6 (IL-6) secretion in whole blood and in both maternal and fetal mononuclear cells. To more specifically identify the progesterone-responsive cell type, we further fractionated mononuclear cells into monocyte and other mononuclear populations and evaluated the induction of IL-6 expression following exposure to LPS and/or progesterone. STUDY DESIGN: Fetal cord blood was obtained from uncomplicated, fullterm pregnancies undergoing cesarean section, and Histopaque-isolated mononuclear cells were fractionated into either monocytes or other mononuclear cell types using Dynabeads (Dynal Biotech). Isolated cell populations were treated with LPS (50 ug/mL), P4 (30 ng/mL) or pretreated with P4 and then exposed to LPS. Following incubation, supernatants were collected and evaluated for secreted IL-6 by ELISA. Data was analyzed using Student t-test and a P-value!0.05 was considered significant. RESULTS: Progesterone significantly blocked LPS induced secretion of IL-6 in fetal mononuclear cells. Following fractionation of mononuclear cells into monocyte and other mononuclear cell populations, IL-6 induction was no longer significantly inhibited by P4. CONCLUSION: In this ex vivo model, P4 exposure does not significantly modulate the pro-inflammatory response of isolated monocytes. The lack of response to P4 following fractionation could result from a required interaction between multiple cell types or alternatively be the consequence of monocyte activation during the isolation technique.

Progesterone receptor isoform C is expressed in fetal and maternal mononuclear cells

Progesterone receptor isoform C is expressed in fetal and maternal mononuclear cells

Specific inhibition of ERK1/2 activation by progesterone blocks LPS induced IL-6 secretion in fetal and maternal mononuclear cells

Specific inhibition of ERK1/2 activation by progesterone blocks LPS induced IL-6 secretion in fetal and maternal mononuclear cells

Hematopoiesis in the feline fetal liver: an assessment by flow cytometry.

The domestic cat is an excellent model for the development of therapeutic protocols that target hematopoietic stem cells (HSCs) because it is relatively resistant to complications related to bone marrow transplantation. To identify a plentiful source of HSC that could be used as targets for gene transduction and transplantation, the livers of 28 mid-gestation fetuses (28-52 days) and late-gestation fetuses (53 days-term) were analyzed for erythroid, myeloid, lymphoid, and uncommitted hematopoietic progenitor cells by flow cytometry. We found that the fetal liver mononuclear cells (FLMCs) contained 57% erythroid progenitors during mid-gestation, but this percentage declined to 43% as gestation progressed. Myelomonocytic cells within FLMC were more numerous in late-gestation (31%) than in mid-gestation (18%). Two monoclonal antibodies (mAb), CH 152 and CH 755, which recognize cells with the potential to reconstitute multilineage hematopoiesis in cats, were tested. Approximately, 32% of FLMC from late-gestation fetuses expressed the epitope recognized by mAb CH 152, a significant increase above the 12% positive cells in mid-gestation fetuses. Approximately, 33% of hepatic mononuclear cells expressed the epitope recognized by mAb CH 755 in both mid-term and late-term fetuses. When expressed in absolute numbers, medians of 2.7 x 10(7) CH 152-positive cells and 3.2 x 10(7) CH 755-positive cells were extracted from the late-term fetal livers of individual cats. T-lymphocytes were a minor component (<3%) of FLMC, despite their presence in the thymus and spleen. These data suggest that the late-term feline fetal liver is a suitable source of mutipotential hematopoietic cells that could be used for gene therapy protocols in the cat.

Phenotypic and functional analysis of human T lymphocytes in early second- and third-trimester fetuses.

This study was undertaken to investigate the phenotypic and functional status of T lymphocytes of human fetuses from early second- to third-trimester. Cord blood samples were obtained from 19 healthy human fetuses (gestation weeks: 18-36), by cordocentesis, and 16 term newborns (gestation weeks 37-42). Maternal and unrelated male blood samples were also taken as controls. Percentage of lymphocytes in fetal white blood cells was 79.3%, reducing to 40% by term birth, much higher than that of adults. Cord blood mononuclear cells (CBMC), prepared by density gradient centrifugation followed by lysis of erythrocytes, were stained using PE- or FITC-labelled monoclonal Abs and analysed by flow cytometry. The frequencies of CD3+ T cells in fetal (40.1%) and neonatal (42.4%) CBMC were significantly lower than that of men (59.6%) and pregnant women (53.6%). Proportions of CD8+ T cells (9.5%), gammadelta-T cells (0.5%) and NK cells (4.8%) in fetal CBMC were also lower than that of neonates (except gammadelta-T cells) and adults. A negative linear correlation (r = -0.609) between the ratio of CD4+/CD8+ T cells in fetal blood and gestation age could also be established. Fetal CBMC showed vigorous spontaneous proliferation but failed to respond to mitogen (PHA) or allogeneic stimulation in vitro. The fetal mononuclear cells were unable to produce IL-2, IL-4 or IFN-gamma, but spontaneously secreted IL-10, IL-6 and TNF-alphain vitro. Stimulation with PHA up-regulated the production of IL-10, IL-6 and TNF-alpha substantially.

422 Metabolic activation of 2′-β-fluoro-2′,3′-dideoxyadenosine and 2′-fluoro-2′-deoadenosine in maternal and fetal peripheral mononuclear cells at term gestation

422 Metabolic activation of 2′-β-fluoro-2′,3′-dideoxyadenosine and 2′-fluoro-2′-deoadenosine in maternal and fetal peripheral mononuclear cells at term gestation

Fetal and neonatal IL-13 production during pregnancy and at birth and subsequent development of atopic symptoms

Background: Cytokine production at the materno-fetal interface may influence the development of atopy-predisposing immune responses. Because IL-13 possesses IL-4–like activity and may regulate the immune responses observed in atopy, it may contribute to the expression of the atopic phenotype initiated during intrauterine life. Objective: We sought to examine IL-13 expression by fetal and neonatal cells and the placenta. Methods: The production of IL-13 by neonatal and fetal T cells was examined by culturing the cells in the presence or absence of PHA. Production of IL-13 at term was considered in the context of the later development of atopic disease in the child. IL-13 expression in the placenta was assessed by using immunohistochemistry. Results: IL-13 immunoreactivity within the placenta was restricted to 16 to 27 weeks’ gestation (6/6 positive vs 0/10 at >27 weeks’ gestation). In contrast, spontaneous release of IL-13 by fetal mononuclear cells was first observed from 27 weeks’ gestation but was undetectable after 37 weeks’ gestation. PHA-stimulated mononuclear cells showed increased IL-13 levels in 80% of samples. Term babies (>37 weeks’ gestation) with a parental history of atopy with atopic symptoms by 3 years of age produced significantly lower concentrations of PHA-induced IL-13 when compared with babies with no parental history of atopy (P = .034). Conclusion: Thus babies at risk of atopic disease in infancy display defective IL-13 production at birth. This may represent an inherent immaturity in the development of T cell–cytokine responses in babies at genetic risk for atopy or could be a consequence of downregulation of responses by other factors. Normal pregnancy, irrespective of atopic status, is associated with the production of appreciable quantities of IL-13 initially by the placenta and subsequently by the fetus. The regulation of this production and its consequences for the mother and fetus remains to be elaborated. (J Allergy Clin Immunol 2000;105:951-9.)