Successful management of severe Kell alloimmunization in pregnancy with intravenous immune globulin.

Hemolytic Disease of the Fetus and Newborn (HDFN) is a condition that affects 1 to 2 out of 1000 patients during pregnancy (1). When an alloantibody is present, it is essential to identify its nature in order to organize appropriate follow-up. Kell-mediated HDFN is rare; it occurs in about 5% of Kell alloimmunized pregnant women. It is important to note that in case of anti-Kell immunization, the severity of HDFN is not correlated with maternal antibody titers, and anemia tends to occur earlier and more severely. Therefore, early diagnosing and management of this condition is crucial. In the management of severe fetal anemia due to Kell immunization, available treatments include in utero transfusion (IUT), immunoglobulin therapy. Other alternative treatments exist, such as plasmapheresis. Intravenous immunoglobulin (IVIG), a noninvasive therapeutic approach, acts through multiple mechanisms. IVIG has been evaluated in cases of RhD immunization with high maternal antibody titers and a history of pregnancies involving early hydrops or intrauterine death. Regarding the potential benefits of intravenous IgG therapy, it may delay the need for early IUT, reduce the overall reliance on IUT, and have a positive impact on obstetric outcomes. This case of IV IgG therapy of anti-Kell immunization offers a thought-provoking avenue for future exploration.

Trogocytosis drives red blood cell antigen loss in association with antibody-mediated immune suppression.

ABSTRACT: Red blood cell (RBC) alloimmunization to paternal antigens during pregnancy can cause hemolytic disease of the fetus and newborn (HDFN). This severe and potentially fatal neonatal disorder can be prevented by the administration of polyclonal anti-D through a mechanism referred to as antibody-mediated immune suppression (AMIS). Although anti-D prophylaxis effectively prevents HDFN, a lack of mechanistic clarity has hampered its replacement with recombinant agents. The major theories behind AMIS induction in the hematologic literature have classically centered around RBC clearance; however, antigen modulation/loss has recently been proposed as a potential mechanism of AMIS. To explore the primary mechanisms of AMIS, we studied the ability of 11 different antibodies to induce AMIS, RBC clearance, antigen loss, and RBC membrane loss in the HOD (hen egg lysozyme-ovalbumin-human Duffy) murine model. Antibodies targeting different portions of the HOD molecule could induce AMIS independent of their ability to clear RBCs; however, all antibodies capable of inducing a strong AMIS effect also caused significant in vivo loss of the HOD antigen in conjunction with RBC membrane loss. In vitro studies of AMIS-inducing antibodies demonstrated simultaneous RBC antigen and membrane loss, which was mediated by macrophages. Confocal live-cell microscopy revealed that AMIS-inducing antibodies triggered RBC membrane transfer to macrophages, consistent with trogocytosis. Furthermore, anti-D itself can induce trogocytosis even at low concentrations, when phagocytosis is minimal or absent. In view of these findings, we propose trogocytosis as a mechanism of AMIS induction.

Case of Hemolytic Disease of the Fetus and Newborn Treated Without Blood Products.

Hemolytic disease of the fetus and newborn (HDFN) affects 3/100,000 to 80/100,000 patients yearly and can cause severe anemia and hyperbilirubinemia. Recombinant human erythropoietin has been used as an adjunct therapy in patients with HDFN and hypo-regenerative anemia in the setting of receiving intrauterine blood transfusions. This case describes a patient with HDFN, in which the family were Jehovah Witnesses, and blood transfusions were declined. The patient had symptomatic anemia with a hematocrit nadir of 18.6%. The patient was successfully treated with recombinant human erythropoietin, ferrous sulfate, and folic acid, avoiding the need for transfusion.

Application of anti-D immunoglobulin in D-negative pregnant women in China.

This article summarizes the current situation of anti-D immunoglobulin (anti-D-Ig) use in RhD-negative pregnant women at home and abroad. The article describes the concept, research and development history, and domestic and foreign applications of anti-D-Ig and points out that anti-D-Ig has not been widely used in China, mainly due to reasons such as unavailability in the domestic market and non-standard current application strategies. The article focuses on analyzing the genetic and immunological characteristics of RhD-negative populations in China. The main manifestations were that the total number of hemolytic disease of the newborn (HDN) relatively high and D variant type. In particular, there are more Asian-type DEL, the importance of clinical application of anti-D-Ig was pointed out, and its antibody-mediated immunosuppressive mechanism was analyzed, which mainly includes red blood cell clearance, epitope blocking/steric hindrance, and Fc γ R Ⅱ B receptor mediated B cell inhibition, anti-D-Ig glycosylation, etc.; clarify the testing strategies of RhD blood group that should be adopted in response to the negative initial screening of pregnant and postpartum women; this article elaborates on the necessity of using anti-D-Ig in RhD-negative mothers after miscarriage or miscarriage, as well as the limitations of its application both domestically and internationally. It also proposes a solution strategy for detecting RhD blood group incompatibility HDFN as early as possible, diagnosing it in a timely manner, and using anti-D-Ig for its prevention and treatment. If the DEL gene is defined as an Asian-type DEL, anti-D-Ig prophylaxis in women would be unnecessary. Finally, based on the specificity of RhD-negative individuals, the article looks forward to the application trend of anti-D-Ig in China. It also called for related drugs to be listed in China as soon as possible and included in medical insurance.

Current Insights Into K-associated Fetal Anemia and Potential Treatment Strategies for Sensitized Pregnancies.

K-associated anemic disease of the fetus and newborn (K-ADFN) is a rare but life-threatening disease in which maternal alloantibodies cross the placenta and can mediate an immune attack on fetal red blood cells expressing the K antigen. A considerably more common disease, D-associated hemolytic disease of the fetus and newborn (D-HDFN), can be prophylactically treated using polyclonal α-D antibody preparations. Currently, no such prophylactic treatment exists for K-associated fetal anemia, and disease is usually treated with intrauterine blood transfusions. Here we review current understanding of the biology of K-associated fetal anemia, how the maternal immune system is sensitized to fetal red blood cells, and what is understood about potential mechanisms of prophylactic HDFN interventions. Given the apparent challenges associated with preventing alloimmunization, we highlight novel strategies for treating sensitized mothers to prevent fetal anemia that may hold promise not only for K-mediated disease, but also for other pathogenic alloantibody responses.

Neonatal hemolytic disease: How should we use indirect and direct antiglobulin tests?

BACKGROUND: In newborns with hemolysis, the direct antiglobulin test (DAT) and indirect antiglobulin test (IAT) play a key role in demonstrating the presence of an immune cause. We aimed to emphasize the importance of IAT in mothers of DAT-positive babies. METHODS: DAT was performed with forward blood grouping on cord blood in term babies who were born between September 2020 and September 2022. IAT was performed in the mothers of the babies who were found to have a positive DAT and antibody identification was performed in the mothers who were found to have a positive IAT. Specific antibodies detected and identified were associated with the clinical course. RESULTS: The study included 2769 babies and their mothers. The prevalence of DAT positivity was found to be 3.3% (87 of 2661). In DAT-positive babies, the rate of ABO incompatibility was 45.9%, the rate of RhD incompatibility was 5.7% and the rate of RhD and ABO incompatibility in association was 10.3%. The rate of subgroup incompatibility and other red blood cell antibodies was 18.3%. Phototherapy was applied because of indirect hyperbilirubinemia in 16.6% of the DAT-negative babies and in 51.5% of the DAT-positive babies. The need for phototherapy was significantly higher in DAT-positive infants (p < 0.01). Severe hemolytic disease of the newborn, bilirubin level, duration of phototherapy and use of intravenous immunoglobulin were found to be significantly higher in the babies whose mothers were IAT positive compared with the babies whose mothers were IAT negative (p < 0.01). CONCLUSIONS: IAT should be performed on all pregnant women. When screening with IAT is not performed during pregnancy, performing DAT in the baby plays a key role. We showed that the clinical course was more severe when mothers of DAT-positive babies were IAT positive.

Fatal hemolytic disease of the newborn due to anti-B Isohemagglutinin: An unfamiliar presentation of a familiar disease.

BACKGROUND: Hemolytic disease of the newborn (HDN) occurs in approximately 1 out of 3000 live births. Severe presentations are atypical but must be recognized and treated rapidly to avoid life-threatening organ dysfunction. CASE PRESENTATION: Here we report an unusual case of neonatal ABO HDN that illustrates the enormous inflammatory potential of maternal-fetal blood group mismatch. Following an uneventful delivery notable only for HDN caused by maternal anti-B IgG, our patient developed shock, DIC, and renal failure. Despite numerous interventions, she experienced a rapid clinical decline and died 10 days after birth. Treatment with whole blood exchange and a monoclonal antibody directed at complement component 5 (eculizumab) were attempted late in the disease course but were unsuccessful. Importantly, this patient had several known risk factors for severe ABO HDN, including the pentad of a group O mother with a group B neonate, high newborn red blood cell B antigen expression, presence maternal anti-B isohemagglutinin in high titer, presence of a maternal IgG anti-B isohemagglutinin, and African ancestry. CONCLUSION: Clinicians should be aware of the potential for severe ABO HDN and consider earlier diagnostic workup and more aggressive therapy in patients with high-risk features.

A study on diagnostic performance of different immunohematological diagnostic tests in assessing the prevalence of ABO Hemolytic Disease of Newborn in the antenatal O group mothers and their neonatal outcome in a tertiary care hospital in Northern India.

BACKGROUND: Hemolytic disease of the newborn (HDN) results in the decreased lifespan of the red cells. HDN related to ABO incompatibility is mostly unnoticed because routine screening is not being done. This study was done to assess the prevalence of ABO-HDN and to compare different immunohematological tests. Methods-In this study 213 O group mothers and the 122 ABO-incompatible newborns born to them were included. Quantifying the maternal IgG anti-A/anti-B antibody titer was done by Conventional Tube Technique (CTT) using Dithiothreitol (DTT) pretreated maternal serum. Hemolysin test was performed on the mothers having titer > 256. These cases were followed up and, after delivery, were monitored for ABO HDN, along with direct antiglobulin testing and elution studies. The prevalence of ABO-HDN was calculated, and the different diagnostic parameters of the tests were calculated. Results- The prevalence of ABO-HDN in our population was estimated to be 1.7%, 6.1% & 10.6% in our population, O group mothers, and O group mothers with ABOincompatible newborns, respectively. Maternal titer≥ 512 strongly correlated with ABOHDN. DAT positivity is a good predictor of ABO-HDN, especially using sensitive techniques. Maternal IgG titers have the highest sensitivity & Negative Predictive Value, while DAT has the highest specificity & Positive Predictive Value. Conclusion - Maternal ABO antibody titration may be advocated in the centers to identify high-risk groups. It can advocate institutional delivery and dedicated follow-up of newborns with ABO-HDN. Blood grouping & DAT may be performed in all newborns born to O blood group to identify high-risk cases.

Immunoglobulin for hemolytic jaundice in Japan: A retrospective survey.

BACKGROUND: Intravenous immunoglobulin G (IVIG) is used to treat blood-type incompatibility hemolytic disease of newborns (BTHDN). Although IVIG's efficacy for treating BTHDN has been challenged, as an updated systematic review suggests, IVIG could significantly reduce exchange transfusions. We conducted a mail-in questionnaire survey to ascertain actual use of IVIG for BTHDN in Japan. METHODS: The survey, conducted in 2014, included infants born between January 1, 2009, and December 31, 2013. Questionnaires were sent to the heads of neonatal intensive care units (NICUs) at perinatal centers of the Japan Neonatologist Association. RESULTS: A total of 195 centers (64.6%) responded to the questionnaire. During the study period, 170 centers (87.2%) reported incidences of BTHDN. Among these centers, there were 1726 diagnosed cases of BTHDN in neonates. Of these cases, 419 infants were treated with IVIG in 127 centers, representing approximately 74.7% of all centers. After the exclusion of cases with missing data and those where consent for data usage was not obtained, a total 916 infants were included in this study. Of these, 219 (23.9%) were treated with IVIG after phototherapy, and 187 (20.4%) of these infants did not require further blood exchange transfusion. The IVIG dosages ranged from 40 to 1200 mg/kg/dose, but the majority were between 500 and 1000 mg/kg/dose, with a median of 800 mg/kg/dose. About 20% of the infants treated with IVIG showed late-onset anemia and required treatment. Adverse events were reported in less than 1% of infants. CONCLUSIONS: For the treatment of BTHDN, IVIG administration was widely used in NICUs in Japan without severe adverse events.

Immunohematological testing and transfusion management of the prenatal patient.

The primary indication for immunohematological testing in the prenatal patient is to detect and identify maternal red cell antibodies. If there are antibodies that are expected to hemolyze the fetus' red cells, their strength of reactivity must be tested, and the fetus' antigen status determined. After delivery, testing is performed to assess the extent of fetomaternal hemorrhage, as a large hemorrhage may require other therapeutic interventions. Another major role for immunohematological testing is to select blood components appropriately when intrauterine transfusion is required for fetal anemia resulting from maternal alloimmunization or some other cause. Supplementation with molecular methods has transformed the practice of immunohematology, particularly as it applies to typing for the D antigen of the Rh blood group system. Notwithstanding the advances in testing, close coordination and communication between the transfusion service and the obstetrics service are the foundation for ensuring the finest care for prenatal patients, and for new mothers and their infants. This review describes testing and transfusion practices for prenatal patients, using case presentations to highlight the management of selected immunohematological findings. It also includes a discussion of key patient management topics that are currently unresolved.

Comparison of automated solid phase versus manual saline indirect antiglobulin test methodology for non-ABO antibody titration: Implications for perinatal antibody monitoring.

BACKGROUND: Accurate antibody titration is crucial in prenatal evaluations to identify patients who need clinical monitoring for hemolytic disease of the fetus and newborn (HDFN) causing fetal anemia. This study compares the established gold standard method of manual tube saline indirect antiglobulin testing (SIAT) with the newer automated solid phase (ASP) method of antibody titration and aims to establish the critical titer threshold for ASP that corresponds to the previously established SIAT critical threshold of ≥16 used in our laboratory. STUDY DESIGN AND METHODS: One hundred fifty-seven prenatal and donor plasma samples with known antibodies were tested using both SIAT and ASP methodologies and results were compared. RESULTS: The study found that ASP titers were, on average, 1.33 dilutions higher than SIAT titers. The critical titer cutoff for ASP was determined to be ≥32, which is one tube higher than the SIAT cutoff of ≥16. DISCUSSION: The ASP method for antibody titration offers greater reproducibility and efficiency compared with manual SIAT titration. This study suggests that a titer cutoff of ≥32 is appropriate for most clinically significant antibodies using ASP. However, further research is needed to determine the comparability of ASP with SIAT in samples with multiple antibodies, anti-M antibodies, and other less common antibodies. Validation of the ASP titer cutoff against HDFN clinical outcomes is required before implementing this test for routine use in perinatal antibody titration.

How do we perform intrauterine transfusions?

BACKGROUND: Intrauterine transfusion (IUT) is an invasive but critical and potentially life-saving intervention for severe fetal anemia with demonstrated improvement in outcomes. The fetus is vulnerable to hemodynamic alterations and transfusion-related adverse events; therefore, special consideration must be given to blood component selection and modification. There is widespread IUT practice variability, and existing guidance primarily relies on expert opinion and single center experiences. STUDY DESIGN AND METHODS: Experts in Maternal Fetal Medicine, Pediatric Hematology, and Transfusion Medicine from centers across the United States, collectively performing about 120 IUT annually, offer a multidisciplinary perspective on the performance of IUT and preparation of blood components. This perspective includes strategies for identifying an at-risk fetus, communicating between disciplines, determining the necessary blood volume, selecting and processing blood components, documenting the procedure in medical record, and managing the neonate. RESULTS: Identifying an at-risk fetus relies on review of the clinical history, non-invasive monitoring, and laboratory evaluation. We recommend the use of relatively fresh, group O, cytomegalovirus-safe, freshly irradiated, red blood cells (RBC) that are Hemoglobin S negative and antigen-negative for any maternal antibody, if indicated. These RBC units should be concentrated to remove additives and increase the hematocrit thus minimizing fluctuations in fetal volume status. The units intended for IUT should be labeled clearly and the documentation of transfusion differentiated in the maternal medical record. DISCUSSION: An awareness of the technical, logistical, and regulatory considerations for IUT performance will facilitate improved communication and patient care, especially when rare units of RBC are required.

Hemolytic disease of the fetus and newborn: rapid review of postnatal care and outcomes.

BACKGROUND: Advances in postnatal care for hemolytic disease of the fetus and newborn (HDFN) have occurred over the past decades, but little is known regarding the frequency of postnatal treatment and the clinical outcomes of affected neonates. Most studies reporting on HDFN originate from high-income countries or relatively large centers, but important differences between centers and countries may exist due to differences in prevalence and available treatment options. We therefore aimed to evaluate the postnatal treatment landscape and clinical outcomes in neonates with Rhesus factor D (Rh(D))- and/or K-mediated HDFN and to provide recommendations for future research. METHODS: We conducted a rapid literature review of case reports and series, observational retrospective and prospective cohort studies, and trials describing pregnancies or children affected by Rh(D)- or K-mediated HDFN published between 2005 and 2021. Information relevant to the treatment of HDFN and clinical outcomes was extracted. Medline, ClinicalTrials.gov and EMBASE were searched for relevant studies by two independent reviewers through title/abstract and full-text screening. Two independent reviewers extracted data and assessed methodological quality of included studies. RESULTS: Forty-three studies reporting postnatal data were included. The median frequency of exchange transfusions was 6.0% [interquartile range (IQR): 0.0-20.0] in K-mediated HDFN and 26.5% [IQR: 18.0-42.9] in Rh(D)-mediated HDFN. The median use of simple red blood cell transfusions in K-mediated HDFN was 50.0% [IQR: 25.0-56.0] and 60.0% [IQR: 20.0-72.0] in Rh(D)-mediated HDFN. Large differences in transfusion rates were found between centers. Neonatal mortality amongst cases treated with intrauterine transfusion(s) was 1.2% [IQR: 0-4.4]. Guidelines and thresholds for exchange transfusions and simple RBC transfusions were reported in 50% of studies. CONCLUSION: Most included studies were from middle- to high-income countries. No studies with a higher level of evidence from centers in low-income countries were available. We noted a shortage and inconsistency in the reporting of relevant data and provide recommendations for future reports. Although large variations between studies was found and information was often missing, analysis showed that the postnatal burden of HDFN, including need for neonatal interventions, remains high. SYSTEMATIC REVIEW REGISTRATION: PROSPERO 2021 CRD42021234940. Available from:  https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021234940 .

Alloimmune hemolytic disease of the fetus and newborn: genetics, structure, and function of the commonly involved erythrocyte antigens.

Hemolytic disease of the fetus and newborn (HDFN) can occur when a pregnant woman has antibody directed against an erythrocyte surface antigen expressed by her fetus. This alloimmune disorder is restricted to situations where transplacental transfer of maternal antibody to the fetus occurs, and binds to fetal erythrocytes, and significantly shortens the red cell lifespan. The pathogenesis of HDFN involves maternal sensitization to erythrocyte "non-self" antigens (those she does not express). Exposure of a woman to a non-self-erythrocyte antigen principally occurs through either a blood transfusion or a pregnancy where paternally derived erythrocyte antigens, expressed by her fetus, enter her circulation, and are immunologically recognized as foreign. This review focuses on the genetics, structure, and function of the erythrocyte antigens that are most frequently involved in the pathogenesis of alloimmune HDFN. By providing this information we aim to convey useful insights to clinicians caring for patients with this condition.

Passive transfer of alloantibodies through breast milk as a mediator of hemolytic anemia.

BACKGROUND: Hemolytic disease of the fetus and newborn (HDFN) is characterized by destruction of fetal/neonatal red blood cells (RBCs) secondary to maternally derived antibodies, which are typically thought to be passively acquired via placental transfer. Few cases have examined the possibility of HDFN mediated by maternal antibodies passively transferred via breast milk. METHODS: We describe two cases of persistent HDFN in infants potentially mediated by passively acquired antibodies via maternal breast milk. We discuss supporting and refuting evidence that may account for this possibility and describe testing methodology illustrating how maternal alloantibodies can be detected in breast milk. RESULTS: In both cases, anti-D antibodies were detected in maternal breast milk. One patient experienced a significant decrease in anti-D plasma titer from 64 to 4 dilutions following 2 weeks of breastfeeding cessation. The other patient experienced a resolution of anemia without breastfeeding cessation. CONCLUSION: There is a paucity of data regarding the lifespan of passively acquired RBC antibodies in neonatal circulation, with significant variation noted between passively acquired IgG based on studies utilizing intravenous immunoglobulin compared to studies of maternally-acquired antiviral IgG antibodies. While our data do not definitively implicate passive transfer of alloantibodies in breast milk as a mediator of HDFN, they do illustrate the need for further investigation into the mechanisms and kinetics of passively acquired antibodies in neonatal circulation.

Clinical significances and distribution of unexpected antibodies found in infants.

INTRODUCTION: The unexpected antibody test is an essential for ensuring the safety of blood transfusions. In infants, different pre-transfusion tests and transfusion strategies are needed due to their immature antigen/antibody system. This study aims to analyze the pattern of unexpected antibodies and their clinical significance in infants. METHODS: A retrospective analysis was conducted on the results of unexpected antibody identification tests performed on infants under one year of age at Asan Medical Center from 1999 to 2022. Patients' unexpected antibody identification test results and clinical information were investigated. The results of unexpected antibody identification and phenotype of each patient's mother were collected. RESULTS: 45 cases of antibody results were studied. 25 cases were found in infants under 4 months of age, and 18 cases (76%) were associated with hemolytic disease of the fetus and newborn (HDFN). The most common unexpected antibody in infants was anti-M (17 cases). There was one case of severe HDFN caused by anti-M. In 10 cases, anti-E and anti-c were found together, and 9 of these cases were associated with HDFN. There were four cases with a history of previous transfusion. CONCLUSIONS: Non-ABO antibodies found in infants showed a different pattern compared to adults. Interpreting unexpected antibody tests in infants, it is important to consider the clinical status of the infant and the test results of the mother, due to possibility of HDFN. To our knowledge, this is the first study to reveal the distribution and clinical significances of unexpected antibodies found in infants in Korea.

Severe hemolytic disease of the newborn caused by JKb antibody: Two case reports and literature review.

BACKGROUND: JKb antibody rarely causes severe hemolytic disease in the newborn except in 1 case, required blood exchange transfusion but later died of intractable seizure and renal failure. Here we describe 2 cases of JKb-induced severe neonatal jaundice requiring blood exchange transfusion with good neurological outcome. CASE PRESENTATION: Two female Chinese, ethnic Han, term infants with severe jaundice were transferred to us at the age of 5- and 4-day with a total bilirubin of 30.9 and 25.9 mg/dL while reticulocyte counts were 3.2% and 2.2%, respectively. Both infants were not the firstborn to their corresponding mothers. Direct and indirect Coombs' tests were positive, and JKb antibody titers were 1:64 (+) for both mothers. Phototherapy was immediately administered, and a blood exchange transfusion was performed within 5 hours of admission. Magnet resonance image showed no evidence of bilirubin-induced brain damage, and no abnormal neurological finding was detected at 6 months of life. CONCLUSION: JKb antibody-induced hemolytic disease of the newborn usually leads to a benign course, but severe jaundice requiring blood exchange transfusion may occur. Our cases suggest good outcomes can be achieved in this minor blood group-induced hemolytic disease of the newborn if identified and managed early enough.