Metabolomics-based study on the significance of differential metabolite binding IgG isoforms in Hemolytic disease of newborn.

BACKGROUND: Hemolytic disease of the newborn (HDN) is a common condition that can have a severe impact on the health of newborns due to the hemolytic reactions it triggers. Although numerous studies have focused on understanding the pathogenesis of HDN, there are still many unanswered questions. METHODS: In this retrospective study, serum samples were collected from 15 healthy newborns and 8 infants diagnosed with hemolytic disease. The relationship between different metabolites and various IgG subtypes in Healthy, HDN and BLI groups was studied by biochemical technique and enzyme-linked immunosorbent assay (ELISA). Metabolomics analysis was conducted to identify the differential metabolites associated with HDN. Subsequently, Pearson's correlation analysis was used to determine the relation of these differential metabolites with IgG isoforms. The relationship between the metabolites and IgG subtypes was observed after treatment. RESULTS: The study results revealed that infants with hemolytic disease exhibited abnormal elevations in TBA, IgG1, IgG2a, IgG2b, IgG3, and IgG4 levels when compared to healthy newborns. Additionally, differences in metabolite contents were also observed. N, N-DIMETHYLARGININE showed negative correlations with TBA, IgG1, IgG2a, IgG2b, IgG3, and IgG4, while 2-HYDROXYBUTYRATE, AMINOISOBUTANOATE, Inosine, and ALLYL ISOTHIOCYANATE exhibited positive correlations with TBA, IgG1, IgG2a, IgG2b, IgG3, and IgG4. Through metabolomics-based research, we have discovered associations between differential metabolites and different IgG isoforms during the onset of HDN. CONCLUSION: These findings suggest that changes in metabolite and IgG isoform levels are linked to HDN. Understanding the involvement of IgG isoforms and metabolites can provide valuable guidance for the diagnosis and treatment of HDN.

An update to Kidd blood group system.

Since publication of the original Immunohematology review of the Kidd blood group system in 2015 (Hamilton JR. Kidd blood group system: a review. Immunohematology 2015;31:29-34), knowledge has mushroomed pertaining to gene structure, alleles causing variant and null phenotypes, clinical significance in renal transplant and hemolytic disease of the fetus and newborn, and physiologic functions of urea transporters in non-renal tissues. This review will detail much of this new information.

Antenatal RHD screening to guide antenatal anti-D immunoprophylaxis in non-immunized D- pregnant women.

In pregnancy, D- pregnant women may be at risk of becoming immunized against D when carrying a D+ fetus, which may eventually lead to hemolytic disease of the fetus and newborn. Administrating antenatal and postnatal anti-D immunoglobulin prophylaxis decreases the risk of immunization substantially. Noninvasive fetal RHD genotyping, based on testing cell-free DNA extracted from maternal plasma, offers a reliable tool to predict the fetal RhD phenotype during pregnancy. Used as a screening program, antenatal RHD screening can guide the administration of antenatal prophylaxis in non-immunized D- pregnant women so that unnecessary prophylaxis is avoided in those women who carry a D- fetus. In Europe, antenatal RHD screening programs have been running since 2009, demonstrating high test accuracies and program feasibility. In this review, an overview is provided of current state-of-the-art antenatal RHD screening, which includes discussions on the rationale for its implementation, methodology, detection strategies, and test performance. The performance of antenatal RHD screening in a routine setting is characterized by high accuracy, with a high diagnostic sensitivity of ≥99.9 percent. The result of using antenatal RHD screening is that 97-99 percent of the women who carry a D- fetus avoid unnecessary prophylaxis. As such, this activity contributes to avoiding unnecessary treatment and saves valuable anti-D immunoglobulin, which has a shortage worldwide. The main challenges for a reliable noninvasive fetal RHD genotyping assay are low cell-free DNA levels, the genetics of the Rh blood group system, and choosing an appropriate detection strategy for an admixed population. In many parts of the world, however, the main challenge is to improve the basic care for D- pregnant women.

Ethical considerations in the use of RhD-positive blood products in trauma.

BACKGROUND: Prehospital and early in-hospital use of low titer group O whole blood (LTOWB) for life-threatening bleeding has been independently associated with improved survival compared to component therapy. However, when RhD-positive blood products are administered to RhD-negative females of childbearing potential (FCP), there is a small future risk of hemolytic disease of the fetus and newborn (HDFN). This raises important ethical questions that must be explored in order to justify the use of RhD-positive blood products, including LTOWB, both in clinical practice and research. METHODS: This essay explores the ethical challenges related to RhD-positive blood product administration to RhD-negative or RhD-unknown FCPs as a first-line resuscitation fluid in the trauma setting. These ethical issues include: issues related to decision-making, ethical analysis based on the doctrine of double effect (DDE), and attendant obligations incurred by hospitals that administer RhD-positive blood to FCPs. RESULTS: Ethical analysis through the use of the DDE demonstrates that utilization of RhD-positive blood products, including LTOWB, in the early resuscitation of FCPs is an ethically appropriate approach. By accepting the risk of HDFN, hospitals generate obligations to promote blood donation, evaluate for alloimmunization and counsel patients on the future risk of HDFN, and maintain an understanding of the ethical rationale for RhD-positive blood transfusion.

Assessing Recommendations for Determining Fetal Risk in Alloimmunized Pregnancies in the United States: Is It Time to Update a Decades-Old Practice?

The current recommended testing algorithm for assessing the alloimmunized pregnancy utilized by many obstetricians in the United States (US) fails to consider the most recent evidence, placing fetuses, and mothers at unnecessary risk of poor outcome or death. This narrative review of the current landscape of fetal red blood cell (RBC) antigen testing evaluates the history of hemolytic disease of the fetus and newborn (HDFN) and how its discovery has continued to influence practices in the US today. We compare current US-based HDFN practice guidelines with those in Europe. We also provide transfusion medicine and hematology perspectives and recommendations addressing the limitations of US practice, particularly regarding paternal RBC antigen testing, and discuss the most valuable alternatives based on decades of data and evidence-based recommendations from Europe.

Genotipificación del gen RHD en ADN fetal libre en plasma de embarazadas RhD negativo / Genotyping of the RHD gene in free fetal DNA in plasma of RhD negative pregnant women

Objetivo: Determinar el grupo RhD fetal a través del estudio del gen RHD en ADN fetal que se encuentra libre en plasma de embarazadas RhD negativo. Método: Se analizó la presencia de los genes RHD, SRY y BGLO en ADNfl obtenido de plasma de 51 embarazadas RhD negativo no sensibilizadas, utilizando una qPCR. Los resultados del estudio genético del gen RHD se compararon con el estudio del grupo sanguíneo RhD realizado por método serológico en muestras de sangre de cordón, y los resultados del estudio del gen SRY fueron cotejados con el sexo fetal determinado por ecografía. Se calcularon la sensibilidad, la especificidad, los valores predictivos y la capacidad discriminativa del método estandarizado. Resultados: El gen RHD estaba presente en el 72,5% de las muestras y el gen SRY en el 55,5%, coincidiendo en un 100% con los resultados del grupo RhD detectado en sangre de cordón y con el sexo fetal confirmado por ecografía, respectivamente. Conclusiones: Fue posible deducir el grupo sanguíneo RhD del feto mediante el estudio del ADN fetal que se encuentra libre en el plasma de embarazadas con un método molecular no invasivo desarrollado y validado para este fin. Este test no invasivo puede ser utilizado para tomar la decisión de administrar inmunoglobulina anti-D solo a embarazadas RhD negativo que portan un feto RhD positivo.

Objective: To determine the fetal RhD group through the study of the RHD gene in fetal DNA found free in plasma of RhD negative pregnant women. Method: The presence of the RHD, SRY and BGLO genes in fetal DNA obtained from plasma of 51 non-sensitized RhD negative pregnant women was analyzed using qPCR. The results of the genetic study of the RHD gene were compared with the RhD blood group study performed by serological method in cord blood samples, and the results of the SRY gene study were compared with the fetal sex determined by ultrasound. Sensitivity, specificity, predictive values and discriminative capacity of the standardized method were calculated. Results: The RHD gene was present in 72.5% of the samples and the SRY gene in 55.5%, coinciding 100% with the results of the RhD group detected in cord blood, and with the fetal sex confirmed by ultrasound, respectively. Conclusions: It was possible to deduce the RhD blood group of the fetus through the study of fetal DNA found free in the plasma of pregnant women with a non-invasive molecular method developed and validated for this purpose. This non-invasive test can be used to make the decision to administer anti-D immunoglobulin only to RhD-negative pregnant women carrying an RhD-positive fetus.

Multidisciplinary management of anti-PP1Pk or anti-P alloimmunization during pregnancy: A new case with anti-P and a literature review.

BACKGROUND: Red blood cell alloimmunization is the first cause of fetal and neonatal anemia. Alloimmunizations with anti-PP1Pk or anti-P can cause recurrent miscarriages and hemolytic disease of the fetus and newborn in the 2nd and 3rd trimesters of pregnancy. We report on a pregnant patient immunized with anti-P and a history of recurrent miscarriages. CASE REPORT: This P2k (GLOB:-1; P1PK:-1,3) patient had a first pregnancy marked by a caesarean at 38 weeks of gestation (WG) for non-reassuring fetal heart rate. Then, she had three early spontaneous miscarriages. The fifth pregnancy began with a high titer of anti-P at 128. Early initiation of treatment with Intravenous Immunoglobulins (IVIg) and plasma exchanges (PE) starting at 5 WG permitted us to reduce the titer of anti-P below 32. A healthy infant was delivered by caesarean at 38 WG without anemia at birth and no exchange transfusion was required. DISCUSSION AND REVIEW OF THE LITERATURE: The P and Pk antigens are expressed on placental, trophoblastic, and embryonic cells. This explains why P1k (GLOB:-1; P1PK:1,3), P2k (GLOB:-1; P1PK:-1,3), or Tj(a-)/p (GLOB:-1; P1PK:-1,-3) patients are prone to recurrent abortions in the first trimester of pregnancy. A literature review demonstrated 87% (68/78) of miscarriages in p patients. However, publication biases are possible with the most severe cases being reported. CONCLUSION: Immunizations to P and PP1Pk antigens differ from others in their physiopathology and precocity. The association of PE and IVIg seems to be an effective treatment in the management of anti-PP1Pk or anti-P fetomaternal incompatibilities.

Conservative Management of Alloimmune Hemolysis and Cholestasis With Extreme Laboratory Abnormalities.

Alloimmune hemolytic disease of the fetus or newborn (HDFN) is a rare cause of neonatal cholestasis. HDFN-associated cholestasis has most often been reported secondary to anti-D alloimmunization. In utero transfusions are also an identified risk factor. A variety of diagnostic and therapeutic strategies have been described, mostly in case reports. Here, we report 2 cases of HDFN-associated cholestasis that were notable for extreme laboratory abnormalities including a peak ferritin of 24 700 ng/mL and a peak alanine aminotransferase of 1406 U/L (33.5-fold upper limit of normal). One case was due to alloimmunization other than anti-D. These cases help define the range of laboratory derangements that are consistent with HDFN-associated cholestasis, including extreme hyperferritinemia. Although in a number of cases, researchers have reported the use of iron chelation in these infants, herein, we describe successful management without iron chelation.

Evaluating automated titre score as an alternative to continuous flow analysis for the prediction of passive anti-D in pregnancy.

OBJECTIVES: To evaluate the potential of the automated titre score (TS) as an alternative method to continuous flow analysis (CFA) for the prediction of the nature of anti-D in pregnancy. BACKGROUND: The 2016 revised British Society for Haematology (BSH) antenatal guidelines recommended a measurement of anti-D concentration by CFA to ensure the detection of potential immune anti-D. Due to high referral costs and resource pressures, uptake has been challenging for hospital laboratories. Serious Hazards of transfusion (SHOT) data have previously shown that this has contributed to missed antenatal follow ups for women with immune anti-D and neonates affected by haemolytic disease of the fetus/newborn. METHODS/MATERIALS: In this multicentre comparative study, samples referred for CFA quantification were also tested by an ORTHO VISION automated anti-D indirect antiglobulin test (IAT) serial dilution and then converted to TS. CFA results and history of anti-D prophylaxis were used to categorise samples as passive or immune, with the aim of determining a potential TS cut-off for CFA referral of at risk patients. RESULTS: Five UK National Health Service (NHS) trusts generated a total of 196 anti-D TS results, of which 128 were classified as passive and 68 as immune. Diagnostic testing of CFA and TS values indicated a TS cut-off of 35 to assist in distinguishing the nature of anti-D. Using this cut-off, 175 (89%) results were correctly assigned into the passive or immune range, giving a specificity of 92.19% and a negative predictive value of 91.47%. CONCLUSION: TS in conjunction with clinical and anti-D prophylaxis history can be used as a viable and cost-effective alternative to CFA in a hospital laboratory setting.

Clinical consequences of the extremely rare anti-PP1Pk isoantibodies in pregnancy: a case series and review of the literature.

BACKGROUND: The absence of the red cell antigens P, P1 and Pk , known as 'p', represents an extremely rare red cell phenotype. Individuals with this phenotype spontaneously form anti-PP1Pk isoantibodies, associated with severe haemolytic transfusion reactions, recurrent spontaneous abortion and haemolytic disease of the fetus and newborn (HDFN). METHODS: We report a series of four successful pregnancies in three women with anti-PP1Pk isoantibodies, one complicated by HDFN, another by intrauterine growth restriction, all managed supportively. We also review the literature regarding the management of pregnancy involving anti-PP1Pk isoimmunization. RESULTS: The literature surrounding anti-PP1Pk in pregnancy is limited to a very small number of case reports. The majority report management with therapeutic plasma exchange (TPE) with or without intravenous immunoglobulin. The relationship between titre and risk of pregnancy loss remains unclear, though a history of recurrent pregnancy loss appears important. Although a positive cord blood direct antiglobulin test is frequently noted, clinically significant HDFN appears uncommon, though possible. CONCLUSION: Early initiation of TPE in high risk patients should be strongly considered. If possible, pregnancies should be managed in a high-risk obstetric or maternal fetal medicine service. The fetus should be monitored closely with interval fetal ultrasound and middle cerebral artery peak systolic volume Doppler to screen for fetal anaemia. Timely sourcing of compatible blood products is likely to be highly challenging, and both directed and autologous donation should be contemplated where appropriate. The International Red Cell Donor Panel may also provide access to compatible products.

Case Report: First Case of Cefotaxime-Sulbactam-Induced Acute Intravascular Hemolysis in a Newborn With ABO Blood Type Incompatibility by the Mechanism of Non-Immunologic Protein Adsorption.

Background: ABO blood type incompatibility hemolytic disease of newborn (ABO-HDN) and drug-induced immune hemolytic anemia (DIIHA) due to non-immunologic protein adsorption (NIPA) mainly cause extravascular hemolysis. All the reported severe DIIHA were caused by drug-induced antibodies, and rare report of acute intravascular hemolysis was caused by the NIPA mechanism or ABO-HDN. Case presentation: We report the first case of acute intravascular hemolysis induced by cefotaxime sodium - sulbactam sodium (CTX - SBT) in a case of ABO-HDN which resulted in death at 55 h after birth. The mother's blood type was O and RhD-positive, and the newborn's blood type was B and RhD-positive. No irregular red blood cell (RBC) antibodies or drug-dependent antibodies related to CTX or SBT was detected in the mother's plasma and the plasma or the RBC acid eluent of the newborn. Before the newborn received CTX - SBT treatment, the result of direct antiglobulin test (DAT) was negative while anti-B was positive (2 +) in both plasma and acid eluent. After the newborn received CTX - SBT treatment, the results of DAT for anti-IgG and anti-C3d were both positive, while anti-B was not detected in plasma, but stronger anti-B (3 +) was detected in acid eluent. In vitro experiments confirmed that NIPA of SBT promoted the specific binding of maternal-derived IgG anti-B to B antigen on RBCs of the newborn, thereby inducing acute intravascular hemolysis. Conclusion: The NIPA effect of SBT promoted the specific binding of mother-derived IgG anti-B in newborn's plasma to the newborn's RBC B antigens and formed an immune complex, and then activated complement, which led to acute intravascular hemolysis. Drugs such as SBT with NIPA effect should not be used for newborns with HDN.

Clinical Implication of Immunohaematological Tests in ABO haemolytic disease of newborn: Revisiting an old disease.

OBJECTIVE: We aimed to assess the frequency distribution of of ABO haemolytic disease of newborn (ABO-HDN) and to know the predictive value of immunohaematological tests in identifying at risk neonates. BACKGROUND: ABO incompatibility, although a common cause of haemolytic disease of newborn, has several unaddressed issues related to it. MATERIAL AND METHODS: A prospective study over 20 months was carried out in a tertiary care centre in South India. Blood grouping, Direct Antiglobulin test (DAT) and elution studies were performed on neonatal samples, whereas blood grouping, antibody screening and antibody titration were performed on maternal samples. In suspected cases, ABO-HDN was diagnosed after excluding other possible causes for haemolysis. The laboratory results were correlated with the clinical details to assess the predictive value of the tests. RESULTS: Of the total 2856 pregnancies, 34% had ABO incompatibility. On testing with columnagglutination test (CAT), the overall DAT positivity and that among ABO-incompatible cases were 3.8% and 11.2%, respectively,) whereas by conventinal tube technique (CTT) it was 0.6% and 2.4% respectively. CAT was found to have higher sensitivity, and the predictive value was higher for CTT. Maternal IgG titre showed a positive linear relationship with the DAT strength and the rise in indirect bilirubin levels. The positive predictive value of combination of tests such as DAT, elution and titation was 94.12%, which was much higher than that of the individual tests. CONCLUSION: DAT positivity is a predictor of early rise in serum bilirubin level, and a combination of tests has a better predictive value than individual tests towards development of clinically significant hyperbilirubinemia in ABO-HDN.

Impact of red blood cell alloimmunization on fetal and neonatal outcomes: A single center cohort study.

BACKGROUND: Alloimmunization can impact both the fetus and neonate. STUDY OBJECTIVES: (a) calculate the incidence of clinically significant RBC isoimmunization during pregnancy, (b) review maternal management and neonatal outcomes, (c) assess the value of prenatal and postnatal serological testing in predicting neonatal outcomes. STUDY DESIGN AND METHODS: A retrospective audit of consecutive alloimmunized pregnancies was conducted. Data collected included demographics, clinical outcomes, and laboratory results. Outcomes included: incidence of alloimmunization; outcomes for neonates with and without the cognate antigen; and sensitivity and specificity of antibody titration testing in predicting hemolytic disease of the fetus and newborn (HDFN). RESULTS: Over 6 years, 128 pregnant women (0.4%) were alloimmunized with 162 alloantibodies; anti-E was the most common alloantibody (51/162; 31%). Intrauterine transfusions (IUTs) were employed in 2 (3%) of 71 mothers of cognate antigen positive (CoAg+) neonates. Of 74 CoAg+ neonates, 58% required observation alone, 23% intensive phototherapy, 9% top up transfusion, and 3% exchange transfusion; no fetal or neonatal deaths occurred. HDFN was diagnosed in 28% (21/74) of neonates; anti-D was the most common cause. The sensitivity and specificity of the critical gel titer >32 in predicting HDFN were 76% and 75%, respectively (negative predictive value 95%; positive predictive value 36%). The sensitivity and specificity of a positive direct antiglobulin test (DAT) in predicting HDFN were 90% and 58%, respectively (NPV 97%; PPV 29%). CONCLUSION: Morbidity and mortality related to HDFN was low; most alloimmunized pregnancies needed minimal intervention. Titers of >32 by gel warrant additional monitoring during pregnancy.

Red blood cell alloimmunization prevalence and hemolytic disease of the fetus and newborn in Israel: A retrospective study.

Hemolytic disease of the fetus and newborn (HDFN) is a severe form of anemia caused by maternal antibodies against fetal red blood cells (RBC) that can cause intrauterine and perinatal morbidity and mortality. The prevalence and specificities of alloantibodies among Israeli pregnant women and clinical outcomes for their fetuses and newborns are unknown. STUDY DESIGN AND METHODS: A retrospective study of women who gave birth between January 1, 2011, and December 31, 2011, was performed. Data were obtained for obstetric admissions from 16 of 27 hospitals, which included results of maternal ABO, D, antibody screens, antibody identification, and requirements for intrauterine or newborn exchange transfusions. RESULTS: Data on 90 948 women representing 70% of all births during 2011 were analyzed. Antibody screen was positive in 5245 (5.8%) women. Alloantibodies, excluding anti-D titer (<16) were identified in 900 (1.0%) women. Of 191 D- women, 75 (39.3%) had anti-D titer of 16 or greater. Other common clinically significant antibodies were anti-E (204, 23%), anti-K (145, 16%), and anti-c (97, 10.8%) alone or in antibody combinations. Multiple alloantibodies were observed in 132 of 900 (15%) of women. Severe HDFN developed in 6.8% (9/132) of these pregnancies. Seventeen fetuses and newborns (0.02% of births) including one set of twins required RBC transfusions. Two fetuses whose mothers had multiple alloantibodies received intrauterine transfusions; one of them was hydropic and died. CONCLUSION: The prevalence of RBC alloantibodies was 1.0% among Israeli pregnant women. Transfusion was required in 0.02% of the fetuses and newborns. Severe HDFN developed in 6.8% of pregnancies with multiple maternal alloantibodies.

Long-term neurodevelopmental outcomes of significant neonatal jaundice in Taiwan from 2000-2003: a nationwide, population-based cohort study.

Newborns with significant neonatal jaundice (SNJ) would admit for evaluation and/or intervention due to an earlier or more rapid increase in bilirubin level. Bilirubin-induced neurological dysfunction in this population might be underestimated. We aimed to investigate the risk of long-term neurodevelopmental sequelae of SNJ in Taiwan. An SNJ 2000-2003 follow-up cohort consisting of 66,983 neonates was extracted from the nationwide, population-based health insurance database in Taiwan to survey the accumulative incidence of long-term (7-year) neurodevelopmental sequelae in comparison to a reference general-population neonate cohort of 12,579 individuals born in 2000. The SNJ follow-up cohort was furtherly categorized into subgroups according to interventions (phototherapy, intensive phototherapy, and exchange transfusion). The SNJ follow-up cohort exhibited significantly higher cumulative rates of long-term neurodevelopmental sequelae than did the reference cohort (P < 0.05). The risks of infantile cerebral palsy, hearing loss, and developmental delay in the SNJ follow-up cohort were between twice and three times of those in the reference cohort after adjusting for gender, comorbid perinatal disorders and urbanization levels. All intervention subgroups demonstrated higher risks for long-term neurodevelopmental sequelae than the reference cohort (P < 0.05) after adjustment. Patients with SNJ are at risk of developing neurodevelopmental disorders during their growth period. A scheduled follow-up protocol of physical and neurodevelopmental assessment during early childhood for these SNJ patients would potentially be helpful for the early detection of and intervention for neurodevelopmental disorders.

Frequency and clinical significance of red cell antibodies in pregnancy - A prospective study from India.

BACKGROUND: For appropriate management of hemolytic disease of the fetus and newborn (HDFN), it is important to detect irregular red cell antibody in the antenatal period. Though it is a simple one-step method, it is not part of routine antenatal screening in many developing countries. To reiterate the importance of antenatal antibody screening, we have assessed the frequency and clinical significance of irregular red cell antibodies in our patient population. MATERIALS AND METHODS: A prospective study was carried out from October 2013 to May 2015 at a tertiary care center from south India. All antenatal samples received by the laboratory for red cell antibody screening were screened using a commercial three-cell screening panel. Antibody identification along with further Immunohematological techniques as required were performed for cases with positive screening results. Neonates of the alloimmunized cases were followed up to determine the clinical significance of the antibody. RESULTS: A total of 2336 antenatal mothers were screened for red cell antibodies. The overall rate of alloimmunization in the study group was 2.27%. Alloimmunization rate among RhD-negative pregnancies was 6.9%. Other than anti-D (49%), we identified anti-D + anti-C (5%), anti-G (5%), anti-c (5%), anti-E (2%), anti-e (2%), anti-H (Bombay phenotype) (7%), anti-M (2%), anti-Lea (2%), anti-Leb (12%), and autoantibodies (9%) in the maternal serum. Anti-D, anti-D + anti-C, anti-G, anti-c, and anti-H were found to be clinically significant in this study. CONCLUSION: This study showed that 1 in 125 RhD-positive pregnancies can develop red cell alloantibodies. Hence, implementing routine antenatal antibody screening irrespective of RhD status is essential.

Poly(I:C) causes failure of immunoprophylaxis to red blood cells expressing the KEL glycoprotein in mice.

Polyclonal anti-D (Rh immune globulin [RhIg]) therapy has mitigated hemolytic disease of the newborn over the past half century, although breakthrough anti-D alloimmunization still occurs in some treated females. We hypothesized that antiviral responses may impact the efficacy of immunoprophylaxis therapy in a type 1 interferon (IFN)-dependent manner and tested this hypothesis in a murine model of KEL alloimmunization. Polyclonal anti-KEL immunoprophylaxis (KELIg) was administered to wild-type or knockout mice in the presence or absence of polyinosinic-polycytidilic acid (poly[I:C]), followed by the transfusion of murine red blood cells (RBCs) expressing the human KEL glycoprotein. Anti-KEL alloimmunization, serum cytokines, and consumption of the transfused RBCs were evaluated longitudinally. In some experiments, recipients were treated with type 1 IFN (IFN-α/ß). Recipient treatment with poly(I:C) led to breakthrough anti-KEL alloimmunization despite KELIg administration. Recipient CD4+ T cells were not required for immunoprophylaxis efficacy at baseline, and modulation of the KEL glycoprotein antigen occurred to the same extent in the presence or absence of recipient inflammation. Under conditions where breakthrough anti-KEL alloimmunization occurred, KEL RBC consumption by inflammatory monocytes and serum monocyte chemoattractant protein-1 and interleukin-6 were significantly increased. Poly(I:C) or type I IFN administration was sufficient to cause breakthrough alloimmunization, with poly(I:C) inducing alloimmunization even in the absence of recipient type I IFN receptors. A better understanding of how recipient antiviral responses lead to breakthrough alloimmunization despite immunoprophylaxis may have translational relevance to instances of RhIg failure that occur in humans.

Resolving Blocked Antigen Phenomenon in Hemolytic Disease of the Fetus and Newborn Due to Anti-K.

High-titer antibodies are a cause of false-negative reactions in red blood cell antigen phenotyping, an event referred to as blocked antigen phenomenon (BAP). In hemolytic disease of the fetus and newborn, BAP complicates laboratory workups as fetal phenotype is helpful in confirming the responsible antibody. Acid elution techniques, techniques using ethylenediaminetetraacetic glycine acid, as well as those using chloroquine diphosphate have been used to resolve BAP; however, ethylenediaminetetraacetic glycine acid destroys K-antigen expression and chloroquine diphosphate is not always effective. We report a case of severe hemolytic disease of the fetus and newborn from anti-K where a modified gentle heat elution resolved BAP. Although infrequently considered with isolated reports in the literature, heat elution is simple, is effective, and involves readily available materials in most blood banks.

Monitoring of prenatal patients using a combined antibody titre for Rh and non-Rh antibodies.

OBJECTIVES: This was a laboratory exercise designed to determine whether combined antibody titrations in the presence of multiple antibodies achieve a critical level earlier or at the same time as antibodies having individual antibody titrations. BACKGROUND: Management of haemolytic disease of the fetus and newborn involves monitoring maternal antibody concentration by antibody titration. Separate titrations are generally performed for each antibody. METHOD: Thirty-one samples containing combinations of two different Rh and/or non-Rh antibodies were examined with separate titres for each antibody and one single combined titration. RESULTS: Of 31 samples, 19 (61.3%) showed an increased combined titre. Of 12 samples that showed no increase, 10 contained a separate titre of <1 for either one or both antibodies. Where both antibodies had a separate titre of ≥1, 15 of 17 (88.2%) showed an increased combined titre. In contrast to the separate titration method, no decrease in titre level was observed using the combined method. CONCLUSION: Where two antibodies are present, titrations performed by a combined method will produce titre levels equal to or higher than antibodies titred individually. Therefore, a combined titration can be expected to reach a critical titre level as early as, or earlier in gestation than, antibodies monitored by a single titration method. Further studies relating fetal outcomes to titration methodology would be valuable in determining the validity of this approach for prenatal management. Cost-effectiveness of this approach to prenatal screening should also be assessed.