The mechanism responsible for diminished neutrophil production in neonates delivered of women with pregnancy-induced hypertension

Clinical utility of gastric fluid cytokine levels in preterm infants for predicting histological chorioamnionitis

BACKGROUND

The risk of various complications, such as neonatal death, early onset sepsis, and chronic lung disease, is increased in infants born to mothers with chorioamnionitis (CAM). However, predicting the diagnosis of histological CAM (hCAM) in the early postnatal period is challenging for clinicians due to pathological considerations. Therefore, an early diagnostic tool for hCAM is needed. Gastric fluid at birth is considered a suitable biomarker for predicting the intrauterine environment because most of its components are from amniotic fluid, and the sampling technique is less invasive. This study aimed to evaluate the clinical utility of cytokines in the gastric fluid of preterm infants at birth as predictors of hCAM.

METHODS

We retrieved gastric fluid and serum from 21 preterm infants with a gestational age of ≤ 32 weeks within 1 h after birth and used cytometric bead array to measure the concentrations of interleukin (IL)-2, IL-4, IL-6, IL-10, tumor necrosis factor-alpha, and interferon-gamma. We compared the cytokine concentrations in the gastric fluid and serum of the preterm infants born to mothers with or without hCAM.

RESULTS

The gastric fluid, serum IL-6, and serum IL-10 concentrations were significantly higher in the hCAM group than that in the non-hCAM group. The best cutoff values for predicting hCAM was > 2,855 pg/mL and > 315 pg/mL for IL-6 in the gastric fluid and serum, respectively. Receiver operating characteristic curves showed that gastric fluid IL-6 concentrations correlated more strongly with the presence of hCAM than serum IL-6 concentrations.

CONCLUSION

IL-6 in the gastric fluid at birth may be a more promising biomarker for predicting the presence of hCAM than that in serum. IL-6 concentration analysis in the gastric fluid at birth might help to diagnose hCAM immediately after birth and improve the prognosis of preterm infants.

Increased mortality in infants with abnormal T-cell receptor excision circles

BACKGROUND

T-Cell Receptor Excision Circles based newborn screening (TREC-NBS) allows for early detection of T-cell lymphopenia in infants with primary immunodeficiency disorders (PIDD). The utility of abnormal TREC-NBS in infants without PIDD is not well studied. We sought to evaluate the association of abnormal TREC-NBS with mortality.

METHODS

365,207 TREC-NBS from October 2011 to December 2014 were reviewed. 467 newborns had abnormal screens and did not meet the criteria for a PIDD diagnosis. Cases were matched to controls (1:3) based on gestational age, birth weight, neonatal intensive care unit status (NICU), and race. Data were obtained through NBS, birth and death certificates records from the Michigan Department of Health and Human Services (MDHHS) databases.

RESULTS

Infants with abnormal TREC-NBS had higher mortality even when PIDD was ruled-out. Transient abnormal TREC-NBS was not associated with higher mortality, but unresolved or late abnormal TREC-NBS was associated with higher mortality. Infants with late abnormal TREC-NBS had severe prematurity, lower birth weight, lower Apgar scores, and higher percentage of congenital anomalies.

CONCLUSION

Infants with abnormal TREC-NBS may be at a higher risk of morbidity and mortality and should be carefully followed, especially if discharged home before a repeat screen can be completed.

IMPACT

This study explores the risk factors and mortality for newborns with secondary T-cell lymphopenia captured on T-Cell Receptor Excision Circles based newborn screening (TREC-NBS). Abnormal TREC-NBS allows for prompt life-saving interventions for primary immunological conditions such as Severe Combined Immunodeficiency (SCID), but can also be associated with non-immunologic conditions. Unresolved and late abnormal TREC-NBS is associated with higher mortality even without primary immunodeficiency, likely detected in infants with more severe prematurity, lower birth weight, and congenital anomalies. TREC-NBS positive infants with secondary T-cell lymphopenia require special attention and close monitoring.

Consequences of early-onset preeclampsia on neonatal morbidity and mortality

Preterm birth is the leading cause of perinatal morbidity and mortality in developed countries. Common reasons for indicated preterm births include pre-eclampsia. The increase in incidences of morbidity and mortality observed in neonates resulting from pregnancies complicated by preeclampsia is also due to alterations in angiogenic and pro-inflammatory factors that directly affect the neonatal health. This review was prepared with the aim of gathering the information available at PubMed/MEDLINE, in the years from 2011 to 2021, on the consequences of neonatal morbidity and mortality of early-onset preeclampsia. There is great controversy in the literature and paucity of studies. Early onset pre-eclampsia has been linked to fetal growth restriction (FGR). Most studies support its association with respiratory distress syndrome (RDS). Most studies point to an association between preeclampsia and bronchopulmonary dysplasia (BPD), with the highest risk in FGR. The association between preeclampsia, patent ductus arteriosus (PDA) and sepsis is not supported by the literature. The association to necrotizing enterocolitis (NEC) is controversial. The risk of spontaneous intestinal perforation (SIP) seems to be increased with preeclampsia. The association between intraventricular hemorrhage (IVH) and preeclampsia is controversial, however, preeclampsia seems to have a protective effect on periventricular leukomalacia (PVL). Most of the evidence points to the non-association between preeclampsia and retinopathy of prematurity (ROP). Hematological changes such as neutropenia, thrombocytopenia and increased nucleated red blood cell counts have been shown to be associated with preeclampsia. The evidence is still quite controversial regarding mortality. The early installation of preeclampsia will have direct consequences on neonatal morbidity. Gestational age at preterm birth is the main risk factor on neonatal morbidity. Obstetricians should aim to prolong the pregnancies complicated by early-onset severe preeclampsia as far as maternal conditions allow. This policy may contribute to improve the neonatal outcomes.

Association of placental histology and neonatal hematologic outcomes

OBJECTIVE

The objective of the paper was to investigate how neonatal hematologic outcomes vary by major placental histopathology categories.

STUDY DESIGN

Placental pathology reports from 5263 subjects were coded into individual placental lesions. Infant hematologic data (complete blood count parameters (n = 1945), transfusions, and phototherapy) were compared by placental pathologic phenotype.

RESULTS

Red blood cell transfusions were more likely with maternal vascular malperfusion (MVM; OR 9.4 [2.2, 40.8]) and chronic inflammation (1.7 [1.04, 2.7]). White blood cells were decreased with MVM (10.6 103/μL vs 16.4) and elevated with acute inflammation (AI; 18.6 vs 11.9). Thrombocytopenia was associated with MVM (OR 3.7 [2.2, 5.1]) and fetal vascular malperfusion (FVM; OR 2.6 [1.5, 4.6]). Platelet transfusions were more likely with MVM (OR 8.3 [4.6, 15.0]) and FVM (OR 2.9 [1.4, 6.1]). Phototherapy was associated with MVM (OR 3.3 [2.7, 4.0]) and AI (OR 0.8 [0.6, 0.9]).

CONCLUSIONS

Neonatal hematologic outcomes are associated with the in utero environment described by placental pathology.

Leukopenia and Neutropenia at Birth and Sepsis in Preterm Neonates of <32 Weeks' Gestation

OBJECTIVE

This study aimed to evaluate associations between leukopenia or neutropenia at birth and risk of sepsis in very preterm neonates.

STUDY DESIGN

We conducted a retrospective unmatched cohort study of neonates of <32 weeks' gestation. Those with leukopenia (≤5,000/µL) were compared with a unmatched cohort without leukopenia. Comparisons were also made for patients with neutropenia and without neutropenia. The outcomes were early-onset sepsis, late-onset sepsis, and mortality.

RESULTS

We identified 271 neonates with leukopenia at birth and 271 without. Multivariable analyses identified higher odds of early-onset sepsis (adjusted odds ratio [AOR] = 4.85, 95% confidence interval [CI]: 1.29-18.20) in leukopenic neonates. Of neonates with leukopenia, 183 had both leukopenia and neutropenia and were associated with the highest odds of early-onset sepsis (AOR = 6.94, 95% CI: 1.77-27.15) compared with those with neither or with either alone.

CONCLUSION

Leukopenia, neutropenia, and both leukopenia and neutropenia at birth were associated with early-onset sepsis in very preterm neonates.

KEY POINTS

· Leukopenia and neutropenia combined at birth was associated with highest odds of early-onset sepsis.. · Leukopenia or neutropenia were associated with sepsis in preterm neonates.. · The risk of infection persist throughout neonatal stay in NICU..

Modulation of preeclampsia by the cholinergic anti-inflammatory pathway: Therapeutic perspectives

The cholinergic anti-inflammatory pathway (CAP) is vital for the orchestration of the immune and inflammatory responses under normal and challenged conditions. Over the past two decades, peripheral and central circuits of CAP have been shown to be critically involved in dampening the inflammatory reaction in a wide array of inflammatory disorders. Additionally, emerging evidence supports a key role for CAP in the regulation of the female reproductive system during gestation as well as in the advent of serious pregnancy-related inflammatory insults such as preeclampsia (PE). Within this framework, the modulatory action of CAP encompasses the perinatal maternal and fetal adverse consequences that surface due to antenatal PE programming. Albeit, a considerable gap still exists in our knowledge of the precise cellular and molecular underpinnings of PE/CAP interaction, which hampered global efforts in safeguarding effective preventive or therapeutic measures against PE complications. Here, we summarize reports in the literature regarding the roles of peripheral and reflex cholinergic neuroinflammatory pathways of nicotinic acetylcholine receptors (nAChRs) in reprogramming PE complications in mothers and their progenies. The possible contributions of α7-nAChRs, cholinesterases, immune cells, adhesion molecules, angiogenesis, and endothelial dysfunction to the interaction have also been reviewed.

Aberrant Hematopoiesis and Morbidity in Extremely Preterm Infants With Intrauterine Growth Restriction

Background and Objective: Intrauterine growth restriction (IUGR) poses additional challenges in extremely low gestational age newborns (ELGANs). We assessed disturbed hematopoiesis and morbidities associated with this disorder. Methods: This single-center retrospective case-control study compared perinatal hematological profiles, major morbidities, and mortality of 49 infants (gestational age <28 weeks, birth weight ≤ 3rd percentile, and compromised placental function) and 98 infants (birth weight >10th percentile) matched for gestational age, year, and sex. Results: IUGR-ELGANs had significantly elevated nucleated red blood cells and lower neutrophil and platelet counts at birth and on the third day of life. During the first week of life, IUGR-ELGANs received more red blood cell, platelet, and plasma transfusions and were more intensively treated with antibiotics. Rates of infections acquired during the first week (59.2 vs. 17.3%, p < 0.001), severe bronchopulmonary dysplasia or death (42.9 vs. 17.3%, p < 0.01), and mortality (36.7 vs. 7.1%, p < 0.001) were markedly elevated in IUGR-ELGANs, but not of hemorrhages or other morbidities. Conclusions: IUGR-ELGANs have high rates of acquired infections during the first week of life and display severe pulmonary morbidity leading to bronchopulmonary dysplasia or death. The high rate of transfusions observed in these infants warrants further scrutiny.

Effect of Maternal Preeclampsia on Hematological Profile of Newborns in Qatar

Background

Preeclampsia is a major cause of pregnancy-related maternal, fetal, and neonatal morbidities and mortalities. We aimed to review the effect of maternal preeclampsia on the hematological profile of newborns in the Qatari population.

Methods

In this case-control study, we reviewed data and complete blood count results of neonates born to Qatari women diagnosed of preeclampsia in 2017 in comparison with data of a control group. Statistical analysis was done using unpaired t-test, chi-square test, and logistic regression analysis.

Results

A total of 108 neonates of women with preeclampsia and 103 neonates of healthy normotensive women were recruited. The mean weight, length, head circumference, placental weight, and gestational age were significantly lower (P < 0.05) in neonates born to women with preeclampsia. Only 13% of babies born to women with preeclampsia developed neonatal thrombocytopenia which is significantly higher compared to only 2% in the control group (chi-square χ² = 9.14; P = 0.003). No significant difference (P > 0.05) was noted between the two groups regarding the white blood cells (WBC) or the absolute neutrophilic count (ANC). Multivariate logistic regression showed that the gestational age, birth weight, length, and ANC had significant association with preeclampsia (P < 0.05).

Conclusions

We found that there was a positive association between preeclampsia and neonatal thrombocytopenia in the Qatari population. Prematurity, placenta insufficiency, fetal growth restriction, and need for neonatal resuscitation were significantly higher in babies born to women with preeclampsia. We recommend that hematological parameters of neonates of those women should be properly monitored to reduce the chances of developing complications.

Medicinal Uses of Hematopoietic Growth Factors in Neonatal Medicine

This review focuses on certain hematopoietic growth factors that are used as medications in clinical neonatology. It is important to note at the chapter onset that although all of the pharmacological agents mentioned in this review have been approved by the US Food and Drug administration for use in humans, none have been granted a specific FDA indication for neonates. Thus, in a sense, all of the agents mentioned in this chapter could be considered experimental, when used in neonates. However, a great many of the pharmacological agents utilized routinely in neonatology practice do not have a specific FDA indication for this population of patients. Consequently, many of the agents reviewed in this chapter are considered by some practitioners to be nonexperimental and are used when they judge such use to be "best practice" for the disorders under treatment.The medicinal uses of the agents in this chapter vary considerably, between geographic locations, and sometimes even within an institutions. "Consistent approaches" aimed at using these agents in uniform ways in the practice of neonatology are encouraged. Indeed some healthcare systems, and some individual NICUs, have developed written guidelines for using these agents within the practice group. Some such guidelines are provided in this review. It should be noted that these guidelines, or "consistent approaches," must be viewed as dynamic and changing, requiring adjustment and refinement as additional evidence accrues.

Changes in Haematological Parameters in Newborns Born to Preeclamptic Mothers - A Case Control Study in a Rural Hospital

INTRODUCTION

Pregnancy is a physiological phenomenon. However, some women develop problems during pregnancy period, which puts both the mother's and the foetus health at risk. Hypertensive disorders of pregnancy are the type of the maternal diseases that can cause the most detrimental effects to the mother and foetus.

AIMS

To determine the haematological parameters in neonates born to preeclamptic mothers.

MATERIALS AND METHODS

It was a prospective case control study carried out on neonates born to preeclamptic mothers in our institute from March 2016 to November 2016. All the haematological parameters of the neonates were recorded and analyzed using SPSS 22.0 version software. Mean, Standard deviation, minimum and maximum values were calculated for continuous variables. The difference between the two groups was compared using independent student 't' test. The p-value <0.05 was considered as statistically significant.

RESULTS

About 120 mothers were included in the study out of which 60 were of study group and 60 of control group. Mean hemoglobin, PCV, red cell count, Mean Corpuscular Volume (MCV), reticulocyte count and nRBC were significantly increased p<0.001, whereas total leucocyte count, mean neutrophil count, absolute neutrophil count, lymphocyte count, platelet count were significantly decreased p<0.001 in babies born to preeclamptic mothers. No difference was found between the two groups in the Mean Corpuscular Haemoglobin (MCH) and Mean Corpuscular Haemoglobin Concentration (MCHC) value p(>0.05).

CONCLUSION

The babies born to preeclamptic mothers are more prone for development of prematurity, low birth weight, Intrauterine Growth Retardation (IUGR), sepsis, neutropenia, leucopenia, thrombocytopenia, increased RBC count, nRBC and reticulocyte count. Early haematological screening helps to decrease morbidity, improve growth, development and survival of the baby.

Effects of maternal hypertension on the neonatal haemogram in southern Nigeria: A case-control study

BACKGROUND

Hypertension in pregnancy is a leading cause of maternal and neonatal morbidity and mortality. This study aimed to compare the hematological parameters in neonates of hypertensive mothers with those of normotensive mothers, and also to compare the incidence of polycythaemia, neutropenia and thrombocytopenia in both groups.

METHODS

This was a hospital-based case control study. Three milliliters of cord blood from neonates of women with hypertension in pregnancy and those of normotensive pregnant women were sampled for haemogram parameters using a 3-part autoanalyser. Haematocrit and white blood cell differentials were done manually. Data were analysed using SPSS version 16.

RESULTS

A total of 200 neonates were recruited, comprising 100 neonates of mothers with hypertensive disorders of pregnancy and 100 neonates of normotensive mothers. The mean haematocrit was significantly higher in neonates of hypertensive mothers than those of normotensive mothers. The neutrophil and platelet counts of neonates of hypertensive mothers were significantly lower than those of normotensive mothers. The incidences of polycythaemia, neutropenia, and thrombocytopenia were found to be 8%, 15%, and 38% among neonates of hypertensive mothers and 0%, 2%, and 8% among neonates of normotensive mothers, respectively. These incidences were significantly different between the groups.

CONCLUSIONS

There was a positive association between hypertension in pregnancy and neonatal polycythaemia, neutropenia, and thrombocytopenia. Haematological parameters of neonates of mothers with hypertension in pregnancy should be properly evaluated and monitored to reduce the chances of developing complications associated with these abnormalities.

Early-Onset Neutropenia in Small-for-Gestational-Age Infants

BACKGROUND

Early neutropenia is more common in small for gestational age (SGA) neonates (birth weight <10th percentile) than in appropriately grown neonates. However, several aspects of this variety of neutropenia are unknown, including the duration, kinetic mechanism, and outcomes.

METHODS

Using 10 years of multihospital records, we studied SGA neonates who, during the first week after birth, had neutrophil counts <1000/μL.

RESULTS

This degree of neutropenia was more common in SGA neonates (6%, 207/3650) than in non-SGA matched controls (1%, 46/3650; P < .001). Neutrophil counts stayed below the lower reference interval for 7 days. Ratios of immature to total neutrophils were within the reference interval, suggesting reduced neutrophil production, not accelerated neutrophil use or destruction. Increased nucleated red cells at birth correlated with decreased neutrophils (P < .001). Neutropenia was not independently associated with maternal hypertensive disorders, over and above the effect of SGA. Of 201 neutropenic SGA neonates, 129 (64%) also had thrombocytopenia. Sixteen percent of neutropenic neonates were treated with recombinant granulocyte colony-stimulating factor (rG-CSF) or intravenous immunoglobulin (IVIG), with no reduction in late-onset sepsis or necrotizing enterocolitis (NEC). Regression analysis showed that neutropenia (but not thrombocytopenia in the absence of neutropenia) was independently associated with increased odds of developing necrotizing enterocolitis (odds ratio 4.01, 90% confidence interval 2.08 to 7.35, P < .001).

CONCLUSIONS

Neutropenia of SGA is a condition of 1-week duration. It is more closely associated with SGA than maternal hypertension (likely owing to neutrophil hypoproduction associated with intrauterine hypoxia), often accompanied by thrombocytopenia, not obviously improved by rG-CSF or IVIG, and associated with an increased risk for NEC.

Blood parameters changes in cord blood of newborns of hypertensive mothers

The aim of this study was to investigate the changes in the peripheral blood of newborns of hypertensive mothers. The umbilical cord blood from newborns of 31 hypertensive mothers and 32 healthy mothers were examined. In all subjects, complete blood count, peripheral blood smear, reticulocyte count, vitamin B12, folate, ferritin levels and hemoglobin electrophoresis were performed. The subjects were followed up on for 1 year in terms of infections. RBC, hemoglobin, reticulocyte count and normoblast count were higher in the newborns of hypertensive mothers compared to the control group, and total leukocytes, neutrophil, lymphocyte, monocyte, eosinophil, and thrombocyte counts were lower. The number of neutropenic and thrombocytopenic subjects in newborns of hypertensive mothers was higher compared to the control group. On peripheral smears, dysplastic changes in neutrophils and erythrocytes were observed with a higher rate in newborns of hypertensive mothers compared to the control group. HbF levels were found to be higher in newborns of hypertensive mothers compared to the control group. During the follow-up period of 1 year, the number of infections in newborns of hypertensive mothers was found to be higher than the control group.

CONCLUSION

Newborns of hypertensive mothers should be carefully evaluated and monitored in terms of hematologic abnormalities. Complete blood counts and peripheral blood smears can be used as significant parameters for early diagnosis of possible complications.

Chemokines plasma levels in preterm newborns of preeclamptic mothers

Information on leukocyte activation in newborn infants of preeclamptic mothers is scarce. IL-8 and GRO-α are the main pro-inflammatory cytokines involved in leukocyte activation. The objective was to evaluate IL-8 and GRO-α plasma levels in preterm newborns infants of preeclamptic mothers. Newborns with gestational age<36 weeks and birth weight<2000 g were included and divided: non-preeclamptic (n=64) and preeclamptic groups (n=55). Exclusion criteria were major congenital malformations, inborn errors of metabolism or chromosomal anomalies, congenital infections, death in delivery room, and maternal chronic hypertension without preeclampsia. IL-8 and GRO-α were measured by enzyme immunoassay in the first 48 h. Groups were similar in birth weight, gestational age, Apgar scores at 5 min, sepsis, RDS, mechanical ventilation, TPN, NEC, intraventricular hemorrhage and death. The preeclamptic group had more neutropenia, SGA, cesarean section, and less rupture of membranes>18 h. IL-8 was higher in the non-preeclamptic [157.1 pg/mL (86.4-261.3) and 26.54 pg/mL (3.6-87.2) p<0.001]. GRO-α levels were similar in both groups [229.5 pg/mL (116.6-321.3) and 185.5 pg/mL (63.9-306.7) p=0.236]. After multiple regression analysis only absence of preeclampsia was associated with high IL-8 levels. Our data suggest that leukocyte activation may be impaired in infants of preeclamptic mothers.

Maternal preeclampsia and neonatal outcomes

Preeclampsia is a multiorgan, heterogeneous disorder of pregnancy associated with significant maternal and neonatal morbidity and mortality. Optimal strategies in the care of the women with preeclampsia have not been fully elucidated, leaving physicians with incomplete data to guide their clinical decision making. Because preeclampsia is a progressive disorder, in some circumstances, delivery is needed to halt the progression to the benefit of the mother and fetus. However, the need for premature delivery has adverse effects on important neonatal outcomes not limited to the most premature infants. Late-preterm infants account for approximately two thirds of all preterm deliveries and are at significant risk for morbidity and mortality. Reviewed is the current literature in the diagnosis and obstetrical management of preeclampsia, the outcomes of late-preterm infants, and potential strategies to optimize fetal outcomes in pregnancies complicated by preeclampsia.

Disorders of the fetomaternal unit: hematologic manifestations in the fetus and neonate

Histoarchitectural characteristics of the human placenta place the fetus at a high risk of growth restriction, abnormal fetomaternal cell traffic, and vertical transmission of pathogens. These abnormalities of the fetomaternal unit are frequently associated with hematological abnormalities in the fetus/neonate and may be the first, most common, or the only clinical manifestations of these conditions. This article reviews the pathophysiology and characteristic hematological manifestations of these conditions in the fetus and the neonate.

Hematologic effects of placental pathology on very low birthweight infants born to mothers with preeclampsia

OBJECTIVE

To investigate the effect of placental pathology on neonatal neutrophils, platelets, hematocrit and nucleated red blood cells in very low birthweight (VLBW) infants born to mothers with preeclampsia.

STUDY DESIGN

Retrospective cohort study of infants with birthweight < 1500 g born to mothers with preeclampsia from july, 2002 to july, 2006 at a single level III neonatal intensive care unit. Placental pathology was reviewed for the presence of placental infarction and vasculopathy. Hematologic parameters from day of life 0, 1 and 2 were obtained. Statistical analysis included repeated-measures analysis of variance and multivariable analysis using logistic regression.

RESULT

The study sample included 203 infants with estimated gestational age of 28+/-3 weeks; 45% had placental infarctions and 26% placental vasculopathy. Infants with neutropenia and thrombocytopenia did not have an increased occurrence of placental infarction or maternal vasculopathy but were more likely to be of small gestational age (SGA) and of lower gestational age compared with infants without neutropenia or thrombocytopenia. After multivariable analysis, gestational age and SGA remained associated with both neutropenia and thrombocytopenia whereas placental infarction and vasculopathy did not remain in the models.

CONCLUSION

In our population of VLBW infants born to mothers with preeclampsia, placental pathology was common. There was no association of placental infarction or vasculopathy with neonatal neutropenia and thrombocytopenia. The data suggest that neonatal hematologic effects of maternal preeclampsia, if related to the placenta, are associated with factors other than placental histology.

Association of BPD and IVH with early neutrophil and white counts in VLBW neonates with gestational age <32 weeks

OBJECTIVE

To investigate associations between early low neutrophil count from routine blood samples, white blood count (WBC), pregnancy complications and neonatal outcomes for very low birth weight infants (VLBW <or=1500 g) with gestational age <32 weeks.

STUDY DESIGN

Information was abstracted on all infants admitted to level III neonatal intensive care units in Wisconsin 2003 to 2004. A total of 1002 VLBW neonates (78%) had differential and corrected total white counts within 2 (1/2) h of birth. Data analyses included frequency tables, binary logistic, ordinal logistic and ordinary regression.

RESULT

Low neutrophil count (<1000 per microl) was strongly associated with low WBC, pregnancy complications and antenatal steroids. Low neutrophil count predicted bronchopulmonary dysplasia severity level (odds ratio, OR: 1.7, 95% confidence interval, CI: 1.1 to 2.7) and intraventricular hemorrhage grade (OR: 2.2, 95% CI: 1.3 to 3.8).

CONCLUSION

Early neutrophil counts may have multiple causes interfering with their routine use as an inflammatory marker. Nonetheless, low neutrophil count has consistent independent associations with outcomes.

Effect of pregnancy induced hypertension on mothers and their babies

OBJECTIVE

To study the hematological profile of mothers with pregnancy induced hypertension and their infants.

METHODS

The effects of maternal hypertension on the hematological profile of neonates were studied in 50 cases comparing the values with that of infants born to normotensive mothers.

RESULTS

There was higher number of preterm, Intra-Uterine Growth Restriction (IUGR) and Small for Gestational Age (SGA) babies among the infants of hypertensive mothers. There was a significantly higher incidence of thrombocytopenia and nucleated RBCs seen in these babies. Significant neutropenia was not documented and there was no increased incidence of bleeding when compared to controls.

CONCLUSION

Although there were significant changes in the hematological profile of infants born to hypertensive mothers, there was no significant increase in neonatal morbidity as a result of these changes.

Dysfunction of innate immunity and associated pathology in neonates

The neutrophils and complement system are the critical elements of innate immunity mainly due to participation in the first line of defense against microorganisms by means of phagocytosis, lysis of bacteria and activation of naive B-lymphocytes. In this report we provide an overview of the up to date information regarding the neutrophil and complement system's functional ability in newborn infants in association with the maternal conditions that exist during the intrauterine stage, gestational age and post-neonatal pathology. The neonates' capacity to control the neutrophil and complement protein activation process has also been discussed because of the evidence that uncontrolled activation of these immune elements provides a significant contribution to the tissue damage and subsequent pathology. The authors are confident that despite the many unanswered questions this review updates their knowledge and points the need for further research to clarify the role of the age-associated dysfunction of neutrophils and complement system in the infection and inflammation related pathology of newborn infants.

Complete blood count parameters for healthy, small-for-gestational-age, full-term newborns

No previous study has investigated the full range of complete blood count (CBC) parameters in small-for-gestational-age (SGA) newborns. The main aim of this study was to compare CBC and peripheral smear parameters in term, healthy SGA neonates and appropriate-for-gestational-age (AGA) neonates, and to establish CBC reference values for full-term SGA newborns. One hundred thirty-two healthy, term newborns (73 SGA and 59 AGA) were included. On day 1, we obtained 109 samples and on day 7 we obtained 77 samples. A CBC and peripheral smear were analyzed for each sample collected and group data were compared. We observed higher mean values for normoblast count, hemoglobin, hematocrit, and red blood cell (RBC) count in the SGA babies than in the AGA babies on day 1. The mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration values for the SGA babies were decreased because of the relatively high RBC count and relatively high mean corpuscular volume we observed in this group. Of the SGA newborns, 21.9% had neutropenia and 4.7% had absolute neutrophil counts lower than 1500/microl on day 1. On both day 1 and day 7, the SGA newborns had higher mean absolute metamyelocyte counts and higher mean I : T (immature : total neutrophil ratio) values than the AGA group. The SGA babies had a lower mean absolute lymphocyte count on day 7 than the AGA group. We detected thrombocytopenia in almost one-third of the 64 SGA newborns tested on day 1. In summary, our study clearly demonstrates that CBC parameters for healthy, full-term, SGA newborns are different from those of healthy, term AGA newborns. This is the first study that has documented different mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, metamyelocyte counts, lymphocyte counts, and I : T in SGA babies compared with AGA babies.

Neonatal neutrophils: the good, the bad, and the ugly

Neonates are at considerable risk for bacterial and fungal infections,due in great part to a variety of age-related impairments in neutrophil function. In addition, evidence suggests that the tendency of the most immature neonates to develop chronic inflammatory disorders is also related to neutrophil dysfunction. This article provides an overview of specific functional deficiencies of neutrophils that have been reported in neonates.

Congenital neutropenia

The term "congenital neutropenia" signifies neutropenia that is present at birth. It includes a wide variety of disorders, some transient and others life long. Some varieties of congenital neutropenia are mild, with blood neutrophil concentrations below normal but not low enough to constitute a significant host defense deficiency. Other varieties of congenital neutropenia are characterized by low blood neutrophil concentrations and a predisposition to repeated infections.

Influence of maternal preeclampsia on recombinant human granulocyte colony-stimulating factor effect in neutropenic neonates with suspected sepsis

AIM

To evaluate the effect of recombinant human granulocyte colony-stimulating factor (rhG-CSF) in preterm neonates with suspected sepsis and severe neutropenia (<1500 mm(3)), and to define the influence of maternal preeclampsia on rhG-CSF activity.

METHODS

Twenty neonates of normotensive mothers (NNMs) (GA 29.2+/-0.5 weeks and BW 1.024+/-81 g) and 20 born to preeclamptic mothers (NPMs) (GA 29+/-0.4 weeks and BW 946+/-55 g) were treated with rhG-CSF, 10 microg/kg per day for 3 days. Complete blood counts were obtained at day 0 (before rhG-CSF administration) and 1-4, 6, 9, 20 and 30 days later.

RESULTS

Absolute neutrophil count (ANC) increased rapidly (three-fold within 24h), and significantly (maximum approximately 20-25 times starting values) and remained within normal range in both groups. However, in NNMs a two-phase increase occurred with an early peak on day 2 and a further peak on day 6 giving significantly higher ANC (P<0.001) than for NPMs at days 2-4 and 6. NPMs showed a gradual ANC increase with a single late peak occurring 3 days later than NNMs (day 9). The highest peak values for ANC were similar (15,900+/-1395 mm(-3) for NNMs and 13,880+/-1097 mm(-3) for NPMs). Neutropenia was completely resolved within 2 days in NNMs and within 4 days in NPMs.

CONCLUSION

Preeclampsia seemed to influence the course of the ANC in spite of rhG-CSF administration, and a higher daily-dose for NPMs with neutropenic sepsis may more rapidly resolve neutropenia by overcoming the preeclampsia-associated inhibitor of rhG-CSF through a dose-dependent mechanism.

Fas and Fas ligand expression in maternal blood and in umbilical cord blood in preeclampsia

The Fas-Fas ligand (FasL) pathway of apoptosis is abnormally activated in diseases associated with impaired immune tolerance or chronic inflammation. Pregnancy-related hypertension is a spectrum of disease that commonly causes significant morbidity in women and in their newborn infants, is associated with generalized inflammation, and may be causally related to impaired maternal-fetal tolerance. Our recent observation of enhanced trophoblast expression of FasL in one form of pregnancy-related hypertension led us to hypothesize that this group of disorders might be associated with abnormal activation of the Fas-FasL pathway. To test this hypothesis, we prospectively quantified soluble and leukocyte-associated Fas receptor and FasL in the maternal and umbilical cord blood (CB) sera of 20 gestations complicated by preeclampsia and of 18 normal control gestations, using ELISA and flow cytometric analyses. We determined higher soluble FasL levels in paired maternal and CB sera of hypertensive gestations compared with control gestations (p < 0.01); in contrast, soluble Fas levels were similar between groups. Surface expression of FasL was lower on maternal (p < 0.01) and CB (p < 0.05) neutrophils from affected gestations, whereas surface Fas expression was lower on maternal (p < 0.02), but not CB, neutrophils and lymphocytes. We conclude that expression of Fas and FasL in sera and on leukocytes is altered in gestations complicated by preeclampsia, and speculate that activation of the Fas-FasL pathway mediates associated pathologic processes in affected women and in their neonates.

A practical approach to evaluating and treating neutropenia in the neonatal intensive care unit

Neutropenia is a relatively common problem in the NICU, recognized in as many as 8% of patients at some time during their hospital stay. In most instances, neutropenia among NICU patients is of short duration and has little influence on outcome. In other cases it is prolonged and severe, and constitutes a serious antimicrobial defense deficiency. When a neonatologist discovers a low blood neutrophil count, choices must be made regarding further evaluation and treatment. The authors hope that the information provided in this article is useful in making these choices.

Evaluation and treatment of thrombocytopenia in the neonatal intensive care unit

Thrombocytopenia is a very frequent problem among sick neonates, affecting up to 35% of all infants admitted to the NICU. Although multiple clinical conditions have been causally associated with neonatal thrombocytopenia, the cause of the thrombocytopenia is unclear in up to 60% of affected neonates. This article provides neonatologists with a practical approach to the thrombocytopenic neonate, with an emphasis on conditions that could be life-threatening or could have significant implications for further pregnancies. An overview of the current therapeutic modalities is also presented, including a discussion of the possible use of recombinant thrombopoietic cytokines to treat certain groups of thrombocytopenic neonates.

Concentrations of serum granulocyte-colony-stimulating factor in normal pregnancy and preeclampsia

OBJECTIVE

In order to elucidate the potential role of granulocyte-colony-stimulating factor (G-CSF) during the course of normal pregnancy and preeclampsia, we measured the serum concentrations of G-CSF in both normal pregnant women and preeclamptic patients.

METHODS

Sera of 10 nonpregnant women, 34 normal pregnant women (n = 10, first trimester; n = 10, second trimester; n = 14, third trimester), 10 postpartum women, 10 mild preeclamptic patients, and 10 severe preeclamptic patients were collected. The serum concentrations of G-CSF were measured by enzyme immunoassay.

RESULTS

The serum level of G-CSF in normal pregnant women (third trimester: 38.3 +/- 15.3 pg/mL; mean +/- SD) was significantly increased when compared with the levels observed in nonpregnant women (20.3 +/- 10.1 pg/mL, p < 0.05), which was similar to the G-CSF concentrations in postpartum subjects (20.7 +/- 9.1 pg/mL). The mild and severe preeclamptic patients showed significantly higher levels of G-CSF (56.9 +/- 18.8 pg/mL, p < 0.05; 73.2 +/- 30.4 pg/mL, p < 0.0001, respectively) than those noted in the third trimester women. The preeclamptic patients who presented with edema had greater (p < 0.01) serum levels of G-CSF (75.5 +/- 25.0 pg/mL) compared with nonedematous patients (44.7 +/- 14.9 pg/mL). The serum levels of G-CSF significantly correlated with both weight gain (p < 0.05), diastolic blood pressure (p < 0.01), and systolic blood pressure (p < 0.01), but not with white blood cell counts.

CONCLUSION

Serum concentrations of G-CSF are increased in normal and, even more so, in preeclamptic pregnancies. Because there was no relationship between serum G-CSF concentration and the number of leukocytes, G-CSF might act not to promote the physiological leukocytosis of pregnancy, but to stimulate the function of leukocytes such as phagocytosis. Moreover, it might be that G-CSF plays important roles in the activation of granulocytes or vascular endothelial injury, which are considered to be important pathological conditions in the development of preeclampsia.

Neoteric physiologic and immunologic methods for assessing early-onset neonatal sepsis

Septicemia is a growing problem among low birth weight infants. Early identification and treatment of sepsis in these infants would help to reduce the high mortality and morbidity seen with this disorder. Newer techniques may make earlier diagnosis a reality. In the following review article, early-onset sepsis in the premature infant is described, specifically focusing on the neonatal inflammatory response, neutropenia, and its somewhat inconsistent and delayed role as a marker for sepsis risk factors. Physiological signs, laboratory indicators, skin temperature, peripheral perfusion, and the interaction of macro-environmental factors are also discussed. Newer (neoteric) immunologic and cytokine markers of sepsis are reviewed. Finally, thermography, a noninvasive bioinstrument measuring vasoactive peripheral perfusion, which has potential for early recognition of neonatal septicemia, is described.

Granulocyte colony-stimulating factor in the cord blood of premature neonates born to mothers with pregnancy-induced hypertension

OBJECTIVES

To estimate the cord blood levels of granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in preterm infants and to study the relationship of these levels to pregnancy-induced hypertension (PIH) and absolute neutrophil counts.

STUDY DESIGN

G-CSF and GM-CSF levels in the cord blood of preterm neonates (n = 74) either with or without maternal PIH were estimated by enzyme-linked immunosorbent assay.

RESULTS

Infants in the PIH group had lower white blood cell, absolute neutrophil, absolute lymphocyte, and monocyte counts. The levels of G-CSF in cord blood were significantly lower in infants whose mothers had PIH (P =.04) and in infants with neutropenia (P =. 01). G-CSF levels were positively correlated with both absolute neutrophil count (P =.02) and total white blood cell count (P =.01). GM-CSF was undetectable in all subjects. According to logistic regression with neutropenia as the dependent variable, only maternal PIH (P <.001), gestational age (P <.001), and G-CSF (P =.01) were independently related.

CONCLUSION

In this study maternal PIH and low gestational age were significantly associated with neutropenia in premature infants. Low G-CSF levels may contribute to the neutropenia that is commonly seen in infants born to mothers with PIH.

A randomized, controlled trial of prophylactic granulocyte-macrophage colony-stimulating factor in human newborns less than 32 weeks gestation

OBJECTIVE

Preterm neonates undergoing intensive care have high morbidity from sepsis. These infants also frequently develop neutropenia, and when this is associated with sepsis, mortality is high. This study investigates the potential for granulocyte-macrophage colony-stimulating factor (GM-CSF) to effect a clinically relevant increase in neutrophil number when used prophylactically in high-risk preterm neonates, and assesses its safety in this population.

DESIGN

In an open, randomized, controlled study, 75 neonates (25 small for gestational age) <32 weeks gestation were randomized to receive GM-CSF (10 microg/kg/d) by subcutaneous injection for 5 days from <72 hours after birth, or to a control group. The primary outcome measure was the neutrophil count during 14 days from study entry. The infants were monitored for potential toxicity. Clinical outcomes, sepsis, and mortality, were recorded, but this initial study was not designed to address clinical benefit.

RESULTS

Prophylactic GM-CSF therapy completely abolished neutropenia in treated infants, when both well and septic, throughout the period of study. Neutropenia (</=1.7 x 10(9)/L) developed in 16 of 39 control infants. Five control infants experienced an acute decrease in neutrophil count coincident with the onset of sepsis. There was no evidence of hematologic, respiratory, or gastrointestinal toxicity in treated infants. Treated infants had a trend to fewer symptomatic, blood culture positive septic episodes than controls during 2 weeks from study entry (11/36 vs 18/39).

CONCLUSION

Five-day prophylactic GM-CSF completely abolishes postnatal neutropenia and sepsis-induced neutropenia in preterm neonates at high risk of sepsis, and so removes an important risk factor for sepsis and sepsis-related mortality.GM-CSF, preterm neonates, neutropenia, sepsis.

Benign ethnic neutropenia: what is a normal absolute neutrophil count?

Approximately 25% to 50% of persons of African descent and some ethnic groups in the Middle East have benign ethnic neutropenia, with low leukocyte and neutrophil counts. It is important to recognize the existence of this condition, the most common form of neutropenia throughout the world, and thus avoid both under-and overevaluation. Although there is no scientific basis for an absolute neutrophil count of 1.5x10(9)/L to be considered minimal, counts below this level are empirically regarded as inadequate in persons of all ethnic groups who are above the age of 1 year. Many individuals, however, maintain consistently low absolute neutrophil counts without evidence of increased susceptibility to infection or any other adverse effect. The important determination is not how many neutrophils are present in the peripheral blood, but whether the bone marrow is able to produce enough normally functioning cells when needed. A description of benign ethnic neutropenia, as set forth in this review, suggests that the lower limit now considered acceptable for the absolute neutrophil count should be readjusted downward for all ethnic groups.

Preliminary report: rhG-CSF may reduce the incidence of neonatal sepsis in prolonged preeclampsia-associated neutropenia

OBJECTIVES

To determine whether adjunctive therapy with recombinant human granulocyte colony-stimulating factor (rhG-CSF) could reverse the neutropenia and reduce the incidence of sepsis (</=28 days postnatal age) in neonates with prolonged preeclampsia-associated neutropenia compared with conventional therapy.

STUDY DESIGN

An intravenous infusion of rhG-CSF (10 microgram/kg/day x 3 days for 10 neonates or 5 microgram/kg/day x 3 days for 5 neonates) was administered to ventilated patients with prolonged (>/=3 consecutive days in the first postnatal week) preeclampsia-associated neutropenia (absolute neutrophil count [ANC] <1500/mm3). Neutrophilic responses and the incidence of neonatal sepsis in the next 28 postnatal days were compared with 13 case-matched control neonates who also had prolonged preeclampsia-associated neutropenia. Sepsis was defined as at least one positive blood culture in a newly symptomatic neonate treated with antibiotics for >/=7 days.

RESULTS

No significant differences existed among the three groups in the birth weight, gestational age, sex, growth retardation, method of delivery, magnitude of respiratory support, use of surfactant, usage of intravascular catheters, or in the initial (pretreatment) ANC. The average baseline ANC (pretreatment) in the 10 microgram rhG-CSF group was 815 +/- 169/mm3 (mean +/- SEM), in the 5 microgram group it was 786 +/- 165/mm3, and in the conventional group it was 965 +/- 283. Eighteen of 28 (64%) neonates with preeclampsia-associated neutropenia were neutropenic at birth, the other 10 (36%) had normal neutrophil counts at birth but subsequently developed >/=3 days of neutropenia between 24 and 120 hours after birth. The ANC increased by 2-fold at 24 hours, by 4-fold at 72 hours, and 14-fold by the 7th day in the 10-microgram group. In the 5-microgram group, a 2-fold and 5-fold increase occurred at 72 hours and 7 days, respectively. In the conventionally-treated group, only a 4-fold increase was seen as late as 7 days after achieving entry criteria. Sepsis was observed in 13% (2/15) of the rhG-CSF-treated neonates compared with an incidence of 54% (7/13) in the conventionally-treated neonates. Conclusions. rhG-CSF increases the ANC significantly (at 10 microgram/kg/day x 3 days) and reduces the incidence of neonatal sepsis in critically ill ventilated neonates with prolonged preeclampsia-associated neutropenia when compared with conventional therapy. A future prospective, randomized, and blinded trial is needed to validate the beneficial effects of prophylactic rhG-CSF therapy in neonates with prolonged preeclampsia-associated neutropenia.

Neonatal neutropenia and thrombocytopenia following maternal hypertension

OBJECTIVE

To assess the relationship between the subtypes of hypertension in pregnancy and subsequent neonatal haematology.

METHODOLOGY

Retrospective review of the haematology of newborns of hypertensive mothers at a tertiary neonatal unit.

RESULTS

Over a 2 year period, 249 infants had full blood examinations. Nineteen (7.6%) were neutropenic and 35 (14.1%) thrombocytopenic, including 11 (4.4%) who were both neutropenic and thrombocytopenic. Neutropenia occurred only in infants whose mothers had severe pre-eclampsia and eclampsia or pre-eclampsia with pre-existing hypertension, whereas thrombocytopenia complicated all maternal hypertension subtypes. Two (10%) of the neutropenic infants developed nosocomial infection while seven (20%) of the thrombocytopenic infants bled. Thirteen (68%) of the neutropenic infants compared with 15 (43%) of the thrombocytopenic infants developed their haematological abnormality within 24 h of birth. All but two infants developed the haematological abnormality by the 5th day of life.

CONCLUSION

Although haematological abnormalities in infants born to hypertensive mothers are uncommon, serious neonatal complications can occur and therefore early haematological screening of these infants is recommended.

Administration of granulocyte colony-stimulating factor to neutropenic low birth weight infants of mothers with preeclampsia

Nine low birth weight infants with neutropenia born to mothers with preeclampsia were treated with granulocyte-colony stimulating factor, 10 micrograms/kg intravenously, within 24 hours of birth and at 24-hour intervals for a maximum of three doses if neutropenia persisted. The absolute neutrophil count increased significantly in eight of the nine infants within 6 hours, and neutrophilia was sustained for at least 72 hours after administration of a single dose of granulocyte-colony stimulating factor.

Effect of granulocyte colony-stimulating factor on preeclampsia-associated neonatal neutropenia

Absolute neutropenia lasting longer than 72 hours after birth occurred in four very low birth weight neonates with a maternal history of severe pregnancy-induced hypertension, and was treated with recombinant granulocyte colony-stimulating factor for 3 days. Absolute neutrophil counts increased nearly four-fold within 48 hours; maximal values were recorded on the ninth day after the infusion was started. Total leukocyte counts subsequently decreased but remained in the normal range. It appears that recombinant human granulocyte colony-stimulating factor promotes a rapid increase in circulating neutrophils in these patients despite the possible presence of a circulating preeclampsia-associated inhibitor of neutrophil production.

Increased incidence of sepsis at birth in neutropenic infants of mothers with preeclampsia

Neutropenia is often found at birth in infants born to mothers with preeclampsia, and is most likely present in utero. To determine whether this neutropenia is associated with an increased incidence of early-onset sepsis, we reviewed the hospital records of 301 low birth weight infants of mothers with preeclampsia. Early-onset sepsis was proved if the result of a culture of blood or cerebrospinal fluid in the first 48 hours of life was positive, or presumed if culture results were negative but two or more clinical signs of sepsis were present and the attending neonatologist believed that an infant was infected and needed at least 7 days of antibiotic therapy. Forty-eight percent of low birth weight infants of mothers with preeclampsia had neutropenia at less than 12 hours of age. Infants with neutropenia had mothers with more severe preeclampsia, were more premature (30 weeks vs 32 weeks), weighed less (1097 gm vs 1615 gm), and were more likely to be small for gestational age. Although maternal and obstetric risk factors for infection were less common in the group with neutropenia, rates of proven or presumed early-onset sepsis were higher (14% vs 2%; p < 0.001). Sepsis was proved in 6% of infants with neutropenia and in none of the infants without neutropenia (p = 0.03). A logistic regression analysis of the relative effects of birth weight, gestational age, and absolute neutrophil count on the incidence of sepsis revealed that only a low absolute neutrophil count correlated significantly with an increased risk of early-onset sepsis in infants with neutropenia.

Plasma granulocyte-colony stimulating factor concentrations ([G-CSF]) in the early neonatal period

We studied G-CSF concentrations ([G-CSF]) at birth and their relationship with neutrophil count, incidence of infection, gestational age, labour, and the presence of maternal pregnancy-induced hypertension. Plasma [G-CSF] were significantly elevated in babies with suspected infection and in those of hypertensive mothers, compared to healthy babies delivered by elective caesarian section (median [range] = 3101 [75- > 5000] pg/ml and 153 [45-857] pg/ml versus 32 [11-266] pg/ml; P < 0.0001); and were unrelated to neutrophil count and gestational age. Initial high concentrations (> 100 pg/ml) declined by 7 d (P < 0.0001).

Increased nosocomial infection in neutropenic low birth weight (2000 grams or less) infants of hypertensive mothers

The neutropenia often seen in infants of hypertensive mothers (IHMs) at < 12 hours of age has been associated with nosocomial infection in the first 18 days of life. To assess maternal hypertension as an independent factor for nosocomial infection, we compared 101 low birth weight (< or = 2.00 kg) IHMs to a concurrent birth weight-matched group of infants of normotensive mothers (INMs). Infants without differential leukocyte counts at < 12 hours of age were excluded, leaving 93 IHMs and 98 INMs. The incidence of neutropenia at < 12 hours among IHMs was not significantly different from that among INMs (42/92 (45%) vs 37/98 (38%)). Nosocomial infection was more frequent in neutropenic IHMs than in neutropenic INMs (12/42 vs 2/37; p = 0.007). Infection in IHMs included omphalitis (2 infants), pneumonia (4), and sepsis with or without meningitis (6); INMs had cellulitis (1) and sepsis (1). The underlying mechanism(s) for this predisposition remains to be elucidated, although limited data suggest that neutropenia may be more severe and prolonged among IHMs.

Erythropoietin affects the maturation pattern of fetal G-CSF-responsive progenitors

A transient hyporegenerative neutropenia has been reported in neonates, but not in older children or adults, undergoing treatment with recombinant erythropoietin (epo). Monocytopenia has not been reported. We postulated that epo might selectively reduce the responsiveness of neonatal progenitors to Granulocyte Colony-Stimulating Factor (G-CSF), while not similarly affecting their responsiveness to Macrophage Colony-Stimulating Factor (M-CSF). To test this hypothesis two types of experiments were performed. First, progenitors of adult or fetal origin were pre-incubated with epo (or control), then washed, and their responsiveness to G-CSF and M-CSF evaluated in clonogenic culture assays. Second, clonogenic maturation was initiated using either G-CSF or M-CSF, after which the effect of a late addition of epo to the developing clones was evaluated. Indeed, pre-incubation with epo resulted in production of fewer neutrophils from fetal progenitors grown in G-CSF (P less than 0.001), but it did not reduce the number of macrophages generated from progenitors grown in M-CSF. Adding epo to the already-developing G-CSF-responsive and M-CSF-responsive adult and fetal clones did not alter colony development. Thus, epo appears to have an action on G-CSF-responsive, but not-M-CSF-responsive fetal progenitors, resulting in reduced production of neutrophils. This effect is no longer apparent, however, when progenitors have matured to the 8-cell clone stage.