Immune hemolytic anemia associated with negative routine serology

Three different pathways of IgM-antibody-dependent hemolysis are mainly regulated by complement

Antibodies to red blood cells (RBCs) may hemolyze erythrocytes via Fc-mediated phagocytosis or complement-dependent. Complement activation on RBCs can be detected by C3d-direct antiglobulin test (DAT), which is the only test in immune hematology that directly targets complement. However, a positive DAT with anti-C3d cannot distinguish between C3b-mediated extravascular hemolysis, C5b-C9-mediated intravascular hemolysis and C5b-C8-mediated eryptosis. Furthermore, DAT is not suitable to estimate the strength of hemolysis. Autoimmune hemolytic anemia (AIHA) is a rare disease that is caused by autoantibodies to red blood cells that is divided in warm AIHA and in cold agglutinin disease (CAD). The causative antibodies in CAD and sometimes in warm AIHA are from the IgM class. Depending on strength of complement activation they can induce extravascular hemolysis, intravascular hemolysis and eryptosis. We studied the three types of hemolysis by use of sera from patients with CAD under various conditions. We found that additionally to the routinely applied C3d-DAT, indirect tests for complement activity (free hemoglobin and Annexin V-binding to phosphatidylserine-exposing RBCs) should be used to determine the portion of extravascular, intravascular and eryptotic hemolysis. Eryptotic hemolysis may have a significant share in clinical relevant CAD or IgM warm AIHA, which should be considered for successful treatment.

Hemolysis-Inspired, Highly Sensitive, Label-Free IgM Detection Using Erythrocyte Membrane-Functionalized Nanomechanical Resonators

Immunoglobulin detection is important for immunoassays, such as diagnosing infectious diseases, evaluating immune status, and determining neutralizing antibody concentrations. However, since most immunoassays rely on labeling methods, there are limitations on determining the limit of detection (LOD) of biosensors. In addition, although the antigen must be immobilized via complex chemical treatment, it is difficult to precisely control the immobilization concentration. This reduces the reproducibility of the biosensor. In this study, we propose a label-free method for antibody detection using microcantilever-based nanomechanical resonators functionalized with erythrocyte membrane (EM). This label-free method focuses on the phenomenon of antibody binding to oligosaccharides (blood type antigen) on the surface of the erythrocyte. We established a method for extracting the EM from erythrocytes and fabricated an EM-functionalized microcantilever (MC), termed EMMC, by surface-coating EM layers on the MC. When the EMMC was treated with immunoglobulin M (IgM), the bioassay was successfully performed in the linear range from 2.2 pM to 22 nM, and the LOD was 2.0 pM. The EMMC also exhibited excellent selectivity compared to other biomolecules such as serum albumin, γ-globulin, and IgM with different paratopes. These results demonstrate that EMMC-based nanotechnology may be utilized in criminal investigations to identify blood types with minimal amounts of blood or to evaluate individual immunity through virus-neutralizing antibody detection.

Direct antibody test negative autoimmune hemolytic anemia with pulmonary tuberculosis: A diagnostic challenge

Tuberculosis (TB) has varied manifestations, but autoimmune hemolytic anemia (AIHA) due to TB is rare. Direct antibody test (DAT) or Coombs negative AIHA is also rare. We report a case of a 14-year-old boy who presented with hemolytic anemia and pneumonia. The Coombs test was repeatedly negative. After ruling out the possible infectious and noninfectious causes by extensive investigations, he was diagnosed as DAT-negative AIHA by monospecific antibody test with 4°C low ionic strength saline washes and column agglutination method which revealed the presence of IgG-2+ antibodies. Bronchoalveolar lavage fluid for acid-fast bacilli and gene Xpert was also positive. It is important to recognize TB as a cause of AIHA in South Asian countries where its incidence is high.

Multiple autoimmune disorders in a patient with neuromyelitis optica spectrum disorder presenting with rhabdomyolysis

Neuromyelitis optica spectrum disorder (NMOSD) is a demyelinating disease of the central nervous system characterised by longitudinal extensive transverse myelitis and involvement of the optic nerve and is associated with many autoimmune disorders. The index case, a known case of Hashimoto's thyroiditis, presented with quadriparesis and tea-coloured urine. Investigations revealed ongoing rhabdomyolysis related to autoimmune myositis and autoimmune haemolytic anaemia leading to pigment-induced acute kidney injury. Suspicion of other autoimmune disease prompted an immunological workup, which showed a positive Schirmer's test and a positive anti-nuclear antibody (ANA) antibody test, disclosing Sjögren's syndrome. Lack of improvement in muscle power with corticosteroids despite reduction in muscle enzymes led to an MRI of the spine, which showed longitudinal extensive transverse myelitis and involvement of the intracranial segment of the right optic nerve. These findings, along with a positive test for aquaporin-4 antibodies, confirmed NMOSD. Treatment with cyclophosphamide led to improvement in muscle power to grade 4 at discharge.

Hemolytic Anemia after Acute Hepatitis B Virus Infection: A Case Report and Systematic Review

Hemolytic anemia and pure red cell aplasia are rare hematological complications of hepatitis B virus infection. We herein report a 24-year-old man who was diagnosed with hemolytic anemia and possible transient pure red cell anemia eight weeks after a severe episode of acute hepatitis B virus infection. Rapid recovery was observed with conservative management. Hemoglobin returned to baseline within three months. As the clinical features of hemolytic anemia associated with hepatitis B virus have not yet been elucidated, we conducted a systematic review and present an analysis of the 20 reported cases, including our present case.

Characteristics and outcomes of autoimmune hemolytic anemia after pediatric allogeneic stem cell transplant

BACKGROUND

Autoimmune hemolytic anemia (AIHA) after allogeneic hematopoietic stem cell transplant (HSCT) is a rare but complex and serious complication. Detailed descriptions of cases and management strategies are needed due to lack of prospective trials.

OBJECTIVES

Describe the incidence, clinical characteristics, and management of AIHA after HSCT in a pediatric cohort.

METHODS

This is a retrospective cohort study of 33 pediatric patients with AIHA after HSCT at an academic tertiary care center from 2003 to 2019.

RESULTS

The overall incidence of AIHA after allogeneic HSCT was 3.8% (33/868). AIHA was significantly more common after transplant for nonmalignant versus malignant diagnoses (7.0% [26/370] vs. 1.4% [7/498], p < .0001). AIHA developed at a median of 4.7 months (range 1.0-29.7) after transplant. Sixteen of 33 patients (48.5%) required new AIHA-directed pharmacologic therapy; 17 (51.5%) were managed on their current immunosuppression and supportive care. Patients managed without additional therapy were significantly older, more likely to have a malignant diagnosis, and tended to develop AIHA at an earlier time point after transplant. Patients received a median of two red blood cell transfusions within the first 2 weeks of diagnosis and a median of one AIHA-directed medication (range one to four), most commonly corticosteroids and rituximab.

CONCLUSIONS

AIHA after HSCT is rare but occurs more commonly in patients transplanted for nonmalignant diagnoses. While some pediatric patients who develop AIHA after transplant can be managed on current immunosuppression and supportive care, many require AIHA-directed therapy including second-line medications.

Diagnostic algorithm for classification and characterization of direct antiglobulin test-negative autoimmune hemolytic anemia with 1-year clinical follow-up

BACKGROUND

Approximately 5%-10% of autoimmune hemolytic anemia (AIHA) cases are negative for direct antiglobulin test (DAT). We previously reported a classification system for untreated patients with DAT-negative AIHA by quantifying levels of red blood cell (RBC)-bound IgG. This study investigated the clinical utility of a novel diagnostic algorithm with a comprehensive classification system and characterized each subgroup in DAT-negative AIHA.

STUDY DESIGN AND METHODS

We assessed 637 patients with undiagnosed hemolytic anemia using our diagnostic algorithm and classification system, which was based on RBC-bound IgG levels and results of column method-DAT before and after washing RBCs.

RESULTS

Patients were diagnosed with DAT-negative AIHA with 97% sensitivity and 84% specificity when the laboratory tests were performed before treatment and classified into the following six categories: tube DAT-negative, low-affinity IgG, double DAT-negative, IgA- or IgM-positive, low-affinity IgM, and s/o non-AIHA. The first three types were major conditions and accounted for 76% of DAT-negative AIHA cases. Based on multivariate analyses of idiopathic DAT-negative AIHA (n = 71), platelet count and albumin concentration were significant factors for survival at 1-year follow-up. The low-affinity IgG group showed the highest platelet count and albumin levels, better response to steroids, and higher 1-year survival rate than those in other groups.

DISCUSSION

Our classification included DAT-negative, IgA-driven, and warm-IgM AIHA categories, which were atypical forms of AIHA with the severe onset and increased risk of relapse. When treating a patient with DAT-negative hemolysis, atypical AIHA should be considered and tested in reference laboratories, especially before treatment.

Autoimmune Hemolytic Anaemias in Pregnancy: Experience in a Tertiary Care Hospital in South India

Background

Autoimmune hemolytic anaemia is very rare and there is limited data regarding their pregnancy outcomes. Hence we aimed to study the maternal and perinatal outcomes in pregnancies with autoimmune hemolytic anaemias (AIHA).

Methods

A retrospective descriptive study of pregnant women with AIHA, who delivered at SJMCH between January 2011 and January 2016 was carried out. Their antenatal and labour records were reviewed and demographic details noted.The primary outcome measures studied were-the prevalence of AIHA, gestational age at delivery, antepartum, intrapartum and postpartum complications, mode of delivery and requirement of transfusion of blood and blood products. The secondary outcome measures studied included neonatal outcomes such as low birth weight, intrauterine growth restriction and need for intensive care. The data is presented as descriptive statistics, including means and percentage.

Results

The prevalence of AIHA was (18/12,420) 0.14%. The mean gestational age at delivery was 34 weeks; 100%, 77% and 50% had antenatal, intra partum or postpartum complications, respectively. 44% had preeclampsia, 38% intrauterine growth restriction and 16% preterm labour. 83% required additional drugs for treatment of AIHA.72% had vaginal delivery; 28% had caesarean delivery; 33% were transfused antenatally and 22% postnatally; 50% of the babies were preterm and required intensive care, 66% had low birth weight. There was no maternal mortality.

Conclusion

Multidisciplinary approach, early diagnosis and detection of autoimmune hemolytic anaemia and complications, good antenatal care, judicious transfusions and delivery at tertiary care centre are the keys to successful outcomes.

Pathogenesis, risk factors and therapeutic options for autoimmune haemolytic anaemia in the post-transplant setting

Autoimmune haemolytic anaemia (AIHA) is a rare complication of allogeneic haematopoietic stem cell transplantation (HSCT), observed with an incidence of 1-5%. Paediatric age, diagnosis of non-malignant disease, lympho-depleting agents in the conditioning regimen, use of unrelated donor, graft versus host disease and infections have been associated with a higher risk of AIHA post HSCT. Post-HSCT AIHA is associated with high mortality and morbidity, and it is often very difficult to treat. Steroids and rituximab are used with a response rate around 30-50%. These and other therapeutic strategies are mainly derived from data on primary AIHA, although response rates in post-HSCT AIHA have been generally lower. Here we review the currently available data on risk factors and therapeutic options. There is a need for prospective studies in post-HSCT AIHA to guide clinicians in managing these complex patients.

Alectinib-induced Immune Hemolytic Anemia in a Patient with Lung Adenocarcinoma

Drug-induced immune hemolytic anemia (DIIHA) is a rare condition with an increasing incidence associated with the frequent use of certain drugs. An 85-year-old woman with lung adenocarcinoma prescribed alectinib complained of dyspnea on exertion at our hospital. Based on her laboratory tests results on admission, we focused on the clinical course of anemia and hemolysis progression after alectinib administration. The patient's anemia and hemolysis gradually improved after discontinuation of alectinib, leading to a diagnosis of alectinib-induced IHA, presented here as the first case encountered in a patient with lung adenocarcinoma. Furthermore, we discuss the importance of correlating clinical laboratory findings in DIIHA.

Primary IgA-mediated Autoimmune Hemolytic Anemia in an Infant Successfully Treated With Rituximab

Autoimmune hemolytic anemia (AIHA) is uncommon in the pediatric population and is often associated with an infectious etiology or postvaccination. Mostly, the child presents with a positive direct antiglobulin test. The diagnosis can be challenging, as in our case with an immunoglobulin A-mediated AIHA. In addition to supportive therapy, such as a red blood cell transfusion, steroids are the first choice of treatment. Rituximab, as second-line treatment, can be given in conjunction. We report the first case of immunoglobulin A-mediated AIHA treated with rituximab in the literature.

[Autoimmune hemolytic anemia: Case review]

INTRODUCTION

Autoimmune hemolytic anemia (AIHA) is a rare and generally self-limiting disease in children.

MATERIAL AND METHODS

A descriptive cross-sectional study was performed in children under 18 years diagnosed with AIHA from January/1997 to July/2019. Clinical variables were collected and AIHA was classified according to the direct antiglobulin test (DAT) in warm AIHA (IgG+/-C3d) and cold AIHA (C3d). Response to treatment and evolution were analyzed.

RESULTS

25 patients were included and 72% were males. The median age at diagnosis was 2 years (range 0.4 to 9). Fever (72%), pallor (68%), jaundice (64%), hepatosplenomegaly and coluria (48%) were the most common presenting symptoms. The median hemoglobin at diagnosis was 5.4 g/dl. DAT was positive in 96%, with detection of IgG antibodies in 76%. A single case presented negative DAT. 20% of the patients associated another cytopenia, one of which was subsequently diagnosed with common variable immunodeficiency. Concomitant viral infection was suspected or documented in 32%. Most of the cases were self-limiting and responded to corticosteroid treatment (72%). Those with partial response (24%), mainly those associated with other cytopenias, required other lines of treatment (rituximab, mycophenolate, immunoglobulins). Complications (32%) and relapses (26%) were detected only in warm AIHA.

CONCLUSIONS

Our case series confirms that AIHA is a very rare disease in childhood. Most cases evolve favorably, although up to a quarter of them require second lines of treatment and, in exceptional cases, they need very aggressive treatments. These latter cases generally correspond to patients who present more than one cytopenia in the course of the disease.

Ceftriaxone-Induced Hemolytic Anemia: A Rare Case Report

INTRODUCTION

Drug-induced immune hemolytic anemia (DIIHA) is a rare complication of any drug therapy, which if not recognized early can be fatal. It is usually underdiagnosed. Ceftriaxone is a commonly used antibiotic in routine practice and is one of the most common drugs to cause DIIHA.

CASE PRESENTATION

We report a case of ceftriaxone-induced immune hemolytic anemia in a 62-year-old woman who had a negative result of a direct antiglobulin test.

DISCUSSION

A review of the literature highlights the salient features of DIIHA and underscores the importance of keeping the suspicion of DIIHA high in the relevant clinical settings because ceftriaxone has been associated with particularly severe outcomes of DIIHA. In cases of unclear hemolysis and despite a negative result of a direct antiglobulin test, the treating physician must keep suspicion of DIIHA high and meticulously look for the possible culprit drugs. Treatment with suspected drugs must be stopped promptly to prevent severe complications and fatal outcomes.

Common presentation of an uncommon anaemia in a resource-limited setting: A diagnostic challenge

A 38-year-old female in the reproductive age group presented with anaemia in a resource-poor setting. The patient was given multiple transfusions during the course of her treatment. After a proper work-up she was diagnosed with Coomb's negative autoimmune haemolytic anaemia (AIHA). She was later treated with steroid and she showed significant improvement. Early diagnosis in her case at the primary care level with other causes of anaemia in mind could have prevented unnecessary transfusions and morbidity. Proper history and approach to anaemia is the key in a resource-poor setting.

Autoimmune Hemolytic Anemia in a Renal Transplant Patient Following Seasonal Influenza Vaccination

Vaccines aim to prevent disease occurrence, its severity, and resultant complications. Our patient, a 58-year-old male, received seasonal influenza vaccination as part of routine health maintenance. Three days later, he presented with malaise, fever, and yellowish discoloration of eyes. His labs showed hyperbilirubinemia, anemia, elevated lactate dehydrogenase, and low haptoglobin, consistent with hemolytic anemia. Autoimmune hemolytic anemia has been associated with vaccine use and may result from phenomena of molecular mimicry and cross-reactivity with the possible role of vaccine adjuvants as well. An underlying structural defect of the red blood cell membrane may make them prone to hemolysis. The differential diagnosis and work-up of hemolytic anemia is extensive, as performed in our case. Management strategies for vaccine-induced hemolysis may involve supportive care, red blood cell transfusion, steroids, and intravenous immunoglobulin.

Role of complement in patients with autoimmune hemolytic anemia and platelet transfusion refractoriness

The complement is a key player of the innate immune response. It provides defense mechanisms that are not specific, but very efficient at neutralizing any invader, accounting for 4% of the proteins in the peripheral blood. Nevertheless, there is a dark side to the complement system, as it may activate its machinery against healthy cells such as peripheral blood red blood cells and platelets resulting in undesired hemolysis and thrombocytopenia, respectively. Understanding and identifying the role of complement in these settings allow physicians to adjust their diagnostic and therapeutic modalities accordingly. The role of complement in the pathophysiology and management of autoimmune hemolytic anemia and of alloimmune-mediated thrombocytopenia is under investigation and discussed.

Characteristics of Bilirubin According to the Results of the Direct Antiglobulin Test and Its Impact in Hemolytic Disease of the Newborn

BACKGROUND

Hyperbilirubinemia, which is a sign of hemolytic disease of the newborn (HDN), can irreversibly damage the central nervous system.

OBJECTIVES

To determine the etiology of HDN in affected patients and characterize the changing pattern of bilirubin using direct antiglobulin testing (DAT).

METHODS

We collected clinical data from newborns who underwent perinatal DAT and from their mothers, between August 2008 and July 2017.

RESULTS

Among 303 neonates, 37 (12.2%) showed positive DAT results. The positive predictive values (PPVs) and negative predictive values (NPVs) based on DAT results were 75.7% and 28.9%, respectively, for starting phototherapy. Bilirubin levels increased more rapidly in the DAT-positive group, compared with the DAT-negative group. The initial bilirubin level differed significantly according to the etiology of hyperbilirubinemia. Further, neonates with anti-D showed higher delta bilirubin per day than neonates with other antibodies.

CONCLUSION

Our results may help to determine the measurement period for bilirubin according to DAT results and etiology.

The first reported case of drug-induced hemolytic anemia caused by dimethyl fumarate in a patient with multiple sclerosis

BACKGROUND

Drug-induced hemolytic anemia is a rare and potentially fatal complication of drug treatment. Specific laboratory tests are crucial to confirm the diagnosis.

CASE REPORT

A 38-year-old woman on treatment with dimethyl fumarate for multiple sclerosis presented with a 7-day history of weakness and fatigue. Laboratory tests revealed profound hemolytic anemia with hemoglobin levels of 4.7 g/dL (reference, 12.5-16.0), decreased haptoglobin, increased reticulocyte count, and increased indirect bilirubin. A first direct antiglobulin test was negative. The patient was started on prednisone 1 mg/kg/day, and dimethyl fumarate was withdrawn. A blood sample was drawn on Day 7 and sent to a reference laboratory. A direct antiglobulin test performed 7 days later was positive. Furthermore, an indirect antiglobulin test was positive only in the presence of the drug.

RESULTS

The patient did not receive a blood transfusion, recovered clinically during the following days, and was discharged on Day 7. On Day 36, the patient's RBCs had normalized. She was changed to another disease-modifying treatment for her multiple sclerosis, and at 10-month follow-up she remained stable without any notable adverse effects.

CONCLUSION

This case describes the first report of a dimethyl fumarate-induced hemolytic anemia. Laboratory results should always be interpreted within the clinical context. Specific laboratory expertise is often needed, given the complexity of the field.

Reliable assessment of the incidence of childhood autoimmune hemolytic anemia

BACKGROUND

Childhood autoimmune hemolytic anemia (AIHA) is a rare and severe disease characterized by hemolysis and positive direct antiglobulin test (DAT). Few epidemiologic indicators are available for the pediatric population. The objective of our study was to reliably estimate the number of AIHA cases in the French Aquitaine region and the incidence of AIHA in patients under 18 years old.

PROCEDURE

In this retrospective study, the capture-recapture method and log-linear model were used for the period 2000-2008 in the Aquitaine region from the following three data sources for the diagnosis of AIHA: the OBS'CEREVANCE database cohort, positive DAT collected from the regional blood bank database, and the French medico-economic information system.

RESULTS

A list of 281 different patients was obtained after cross-matching the three databases; 44 AIHA cases were identified in the period 2000-2008; and the total number of cases was estimated to be 48 (95% confidence interval [CI]: 45-55). The calculated incidence of the disease was 0.81/100,000 children under 18 years old per year (95% CI 0.76-0.92).

CONCLUSION

Accurate methods are required for estimating the incidence of AIHA in children. Capture-recapture analysis corrects underreporting and provides optimal completeness. This study highlights a possible under diagnosis of this potentially severe disease in various pediatric settings. AIHA incidence may now be compared with the incidences of other hematological diseases and used for clinical or research purposes.

A Rare Case of Successfully Treated Coombs Negative Immune Haemolytic Anaemia in Pregnancy

Immune haemolytic anaemia in pregnancy, although rare, but it can be life threatening. Severe anaemia with jaundice, unresponsive to blood transfusion can clinch the diagnosis of immune haemolytic anaemia. Our patient was a 27-year-old second gravida, with all the above features, but there was diagnostic challenge as her Coombs test was negative. A high index of suspicion and rapid response to glucocorticoids, pointed towards the diagnosis. Thereafter, the course of pregnancy and postpartum period was uneventful. Thus, successful maternal and fetal outcome can be achieved with prompt diagnosis and treatment.

How I treat autoimmune hemolytic anemia

Autoimmune hemolytic anemia (AIHA) is an uncommon entity that presents diagnostic, prognostic, and therapeutic dilemmas despite being a well-recognized entity for over 150 years. This is because of significant differences in the rates of hemolysis and associated diseases and because there is considerable clinical heterogeneity. In addition, there is a lack of clinical trials required to refine and update standardized and evidence-based therapeutic approaches. To aid the clinician in AIHA management, we present four vignettes that represent and highlight distinct clinical presentations with separate diagnostic and therapeutic pathways that we use in our clinical practice setting. We also review the parameters present in diagnostic testing that allow for prognostic insight and present algorithms for both diagnosis and treatment of the AIHA patient in diverse situations. This is done in the hope that this review may offer guidance in regard to personalized therapy recommendations. A section is included for the diagnosis of suspected AIHA with negative test results, a relatively infrequent but challenging situation, in order to assist in the overall evaluation spectrum for these patients.

The Direct Antiglobulin Test: Indications, Interpretation, and Pitfalls

The direct antiglobulin test (DAT; sometimes referred to as the "Coombs" test) continues to be one of the most widely used assays in laboratory medicine. First described about 70 years ago, it is elegantly simple in design, yet it is widely complex in its applications and interpretations, and it is prone to false-positive and false-negative results. The overall objective of our review is to provide practicing pathologists with a guide to identify situations when the DAT is useful and to highlight disease-specific shortcomings as well as general pitfalls of the test. To accomplish these goals, this review will discuss the following: (1) the history of the DAT, (2) how the test is performed in the clinical laboratory, (3) clinical situations for its use, (4) its interpretation, and (5) the pitfalls associated with DAT assays, including causes of false positivity.

The Kidd (JK) Blood Group System

The Kidd blood group system was discovered in 1951 and is composed of 2 antithetical antigens, Jk^a and Jk^b, along with a third high-incidence antigen, Jk3. The Jk3 antigen is expressed in all individuals except those with the rare Kidd-null phenotype. Four Kidd phenotypes are therefore possible: Jk(a+b-), Jk(a-b+), Jk(a+b+), and Jk(a-b-). The glycoprotein carrying the Kidd antigens is a 43-kDa, 389-amino acid protein with 10 membrane-spanning domains which functions as a urea transporter on endothelial cells of the renal vasa recta as well as erythrocytes. The HUT11/UT-B/JK (SLC14A1) gene encoding this glycoprotein is located on chromosome 18q12-q21. The Jk^a and Jk^b antigens are the result of a single-nucleotide polymorphism present at nucleotide 838 resulting in an aspartate or asparagine amino acid at position 280, respectively. The Kidd blood group can create several difficult transfusion situations. Besides the typical acute hemolytic transfusion reactions common to all clinically relevant blood group antigens, the Kidd antigens are notorious for causing delayed hemolytic transfusion reactions due to the strong anamnestic response exhibited by antibodies directed against Kidd antigens. The Kidd-null phenotype is extremely rare in most ethnic groups, but is clinically significant due to the ability of those with the Kidd-null phenotype to produce antibodies directed against the high-incidence Jk3 antigen. Anti-Jk3 antibodies behave in concordance with anti-Jk^a or anti-Jk^b possessing the capability to cause both acute and delayed hemolytic reactions. Antibodies against any of the 3 Kidd antigens can also be a cause of hemolytic disease of the fetus and newborn, although this is generally mild. In this review, we will outline the makeup of the Kidd system from its historical discovery to the details of the Kidd gene and glycoprotein, and then discuss the practical aspects of Kidd antibodies and transfusion reactions with an extended focus on the Kidd-null phenotype. We will end with a brief discussion of the donor aspects related to the screening and supply management of blood from donors with the rare Jk(a-b-) phenotype.

Clinically and/or Serologically Misleading Findings Surrounding Immune Haemolytic Anaemias

Autoimmune haemolytic anaemias (AIHAs) are well-characterized disorders. They can be differentiated from one another and from other non-immune haemolytic anaemias by clinical, laboratory and serological testing. However, several misleading clinical presentations and/or serological findings may result in misinterpretation, delay and/or misdiagnosis. Such failures are avoidable by adequate clinical and serological experience of the responsible physicians and serologists or, at least, by an optimised bidirectional communication. As long as this has not been achieved, unpleasant failures are to be expected. A true diagnosis of AIHA can neither be verified by clinical nor serological findings alone. Thus, a collective clinical and serological picture remains obligatory for fulfilling the criteria of optimal diagnosis and therapy. Ultimately, the majority of pioneer scientific and practical work in this field stems from scientists who were simultaneously involved in both the clinic and serology.

Profound autoimmune hemolysis and Evans syndrome in two asplenic patients with babesiosis

BACKGROUND

Evans syndrome (ES) is characterized by the simultaneous or sequential presence of multiple autoimmune cytopenias. It is often secondary to rheumatologic disorders or lymphoid malignancies, but has not previously been associated with babesiosis. Here we present two cases of severe cytopenias in asplenic patients precipitated by active babesiosis.

CASE REPORT

The first patient had a history of Hodgkin's lymphoma in remission and autoimmune hemolytic anemia (AIHA) treated by splenectomy 12 years prior who presented with severe AIHA and thrombocytopenia after Babesia infection. The second patient had a history of ES requiring splenectomy, which relapsed after Babesia infection.

RESULTS

The complex presentation and medical histories of both patients made the diagnosis challenging. Both patients' cytopenias responded to therapy, although the use of immunosuppressive agents in patients with active hematologic infections was challenging and required a multidisciplinary approach.

CONCLUSION

These two cases illustrate the possibility of babesiosis to not only reactivate ES in asplenic patients, but also precipitate increased levels of immune deregulation, potentially provoking ES, a phenomenon not previously reported.

Simultaneous detection of IgG, IgM, IgA complexes and C3d attached to erythrocytes by flow cytometry

INTRODUCTION

Immune complexes attached to erythrocyte membrane are involved in autoimmune hemolytic anemia (AIHA) pathogenesis. Currently, direct antiglobulin test (DAT) is used for AIHA diagnosis; however, its performance can be variable. The aim of this study was to design a flow cytometry protocol for simultaneous detection of IgG, IgM, IgA immune complexes and C3d attached to erythrocytes in AIHA patients .

METHODS

A procedure was standardized for assessing independent or simultaneous IgG, IgM, IgA immune complexes and C3d, which were detected using secondary antibodies. The protocol developed was applied to blood samples of patients with AIHA, donors at risk of developing the disease, and healthy controls.

RESULTS

Twenty-four blood samples were assessed: nine patients with AIHA, five donors at risk of developing the disease, and 10 healthy controls. In the AIHA group, all were positive for C3d, seven for IgG, four for IgA, and one for IgM. Two AIHA patients that were negative for DAT-IgG and C3d were positive for C3d by flow cytometry.

CONCLUSION

Flow cytometry is a consistent method for identifying the presence of IgG, IgM, IgA immune complexes and C3d attached to erythrocytes and can be helpful for understanding the mechanisms involved in AIHA pathogenesis.

Diagnostic and therapeutic challenges of primary autoimmune haemolytic anaemia in children

Autoimmune haemolytic anaemias (AIHAs) are extracorpuscular haemolytic anaemias produced by antierythrocyte autoantibodies which cause a shortened red blood cell life span. There are several reasons why the diagnosis and treatment of AIHAs in children represent a bigger challenge than in adult patients, including the presence of particular AIHA types, the uncertainty of serological tests and the limited clinical experience. All these facts have added up to a poor understanding and management of some topics in childhood AIHA. We discuss some of these questions, for example, the occurrence of AIHA with negative direct antiglobulin (Coombs) test, the correct diagnosis and actual incidence of paroxysmal cold haemoglobinuria, the most appropriate second-line therapy of AIHA in childhood or the management of transfusion procedures in these patients. This review takes a practical point of view, providing with some ground rules on how to identify and deal with these paediatric patients.

Survival of red blood cells after transfusion: processes and consequences

THE CURRENTLY AVAILABLE DATA SUGGEST THAT EFFORTS TOWARD IMPROVING THE QUALITY OF RED BLOOD CELL (RBC) BLOOD BANK PRODUCTS SHOULD CONCENTRATE ON: (1) preventing the removal of a considerable fraction of the transfused RBCs that takes place within the first hours after transfusion; (2) minimizing the interaction of the transfused RBCs with the patient's immune system. These issues are important in reducing the number and extent of the damaging side effects of transfusions, such as generation of alloantibodies and autoantibodies and iron accumulation, especially in transfusion-dependent patients. Thus, it becomes important for blood bank research not only to assess the classical RBC parameters for quality control during storage, but even more so to identify the parameters that predict RBC survival, function and behavior in the patient after transfusion. These parameters are likely to result from elucidation of the mechanisms that underly physiological RBC aging in vivo, and that lead to the generation of senescent cell antigens and the accumulation of damaged molecules in vesicles. Also, study of RBC pathology-related mechanisms, such as encountered in various hemoglobinopathies and membranopathies, may help to elucidate the mechanisms underlying a storage-associated increase in susceptibility to physiological stress conditions. Recent data indicate that a combination of new approaches in vitro to mimick RBC behavior in vivo, the growing knowledge of the signaling networks that regulate RBC structure and function, and the rapidly expanding set of proteomic and metabolomic data, will be instrumental to identify the storage-associated processes that control RBC survival after transfusion.

Hemolytic anemia in adults: main causes and diagnostic procedures

Hemolytic anemia is not an exceptional situation in adults. Although establishing the hemolytic mechanism of an anemia is usually rather easy, finding the etiology may be quite difficult as both hereditary (corpuscular) and acquired causes of hemolytic anemia may occur during adulthood. The diagnosis of hemolytic anemia, therefore, requires a multistep procedure taking into account both the patient's and family history, a careful analysis of the blood smear and a direct antiglobulin test. Based on these first data, the diagnostic procedure may then require more specific tests whose indications are discussed in this review.

The direct antiglobulin test: a critical step in the evaluation of hemolysis

The direct antiglobulin test (DAT) is a laboratory test that detects immunoglobulin and/or complement on the surface of red blood cells. The utility of the DAT is to sort hemolysis into an immune or nonimmune etiology. As with all tests, DAT results must be viewed in light of clinical and other laboratory data. This review highlights the most common clinical situations where the DAT can help classify causes of hemolysis, including autoimmune hemolytic anemia, transfusion-related hemolysis, hemolytic disease of the fetus/newborn, drug-induced hemolytic anemia, passenger lymphocyte syndrome, and DAT-negative hemolytic anemia. In addition, the pitfalls and limitations of the test are addressed. False reactions may occur with improper technique, including improper washing, centrifugation, and specimen agitation at the time of result interpretation. Patient factors, such as spontaneous red blood cell agglutination, may also contribute to false results.

Post-transfusion survival of biotin-labeled allogeneic RBCs in adult horses

BACKGROUND

Post-transfusion survival of allogeneic RBCs has been reported to be much shorter in horses than in other species. We hypothesized that post-transfusion survival of biotinylated allogeneic equine RBCs would be greater than the survival previously reported from studies using radioactive RBC-labeling techniques.

OBJECTIVE

The study objective was to determine post-transfusion survival of N-hydroxysuccinimide (NHS)-biotin-labeled allogeneic equine RBCs transfused into adult horses.

METHODS

Horses were adults and included 5 donors and 5 recipients. All horses were blood-typed, and donors were paired with recipients based upon blood type and crossmatch results. Donor blood was collected in a volume of 4 L into citrate phosphate dextrose adenine-1 and stored for 24 hours, labeled with NHS-biotin, and re-infused into recipients. Post-transfusion blood samples were collected at 15 minutes and at 1, 2, 3, 5, 7, 14, 21, 28, and 35 days. Biotin-labeled RBCs were detected by flow cytometry using streptavidin-phycoerythrin. Post-transfusion survival at 24 hours, lifespan, and half-life of biotinylated RBCs were determined.

RESULTS

Mean ± SD survival of biotinylated RBCs at 24 hours post-transfusion was 95 ± 24%; the mean lifespan of transfused allogeneic RBCs was 39 days based on calculation of a linear regression survival curve, and mean post-transfusion RBC half-life was 20 days.

CONCLUSIONS

Post-transfusion survival of 24-hour stored equine allogeneic RBCs was greater than previously reported but less than that observed for other companion animal species. Mechanisms for the relatively short post-transfusion lifespan of allogeneic equine RBCs remain unknown and warrant further study.