Direct antiglobulin (“Coombs”) test-negative autoimmune hemolytic anemia: A review

Transfusion support and pre-transfusion testing in autoimmune haemolytic anaemia

Autoimmune haemolytic anaemia (AIHA) is characterized by an increased destruction of red blood cells due to immune dysfunction and auto-antibody production. Clinical manifestations are mainly related to anaemia, which can become life-threatening in case of acute haemolysis. Aiming at counterbalancing severe anaemia, supportive treatments for these patients frequently include transfusions. Unfortunately, free serum auto-antibodies greatly interfere in pre-transfusion testing, and the identification of compatible red blood cell units for AIHA patients can be challenging or even impossible. Problems faced in pre-transfusion testing often lead to delay or abandonment of transfusions for AIHA patients. In this review, we discuss publications concerning global transfusion management in AIHA, with a focus on pre-transfusion testing, and practical clues to manage the selection of transfusion units for these patients. Depending on the degree of transfusion emergency, we propose an algorithm for the selection and laboratory testing of units to be transfused to AIHA patients.

A Case of Coombs-Negative Primary Warm Autoimmune Hemolytic Anemia Due to IgA Antibody That Responded Well to Rituximab and Steroids

Warm autoimmune hemolytic anemia (WAIHA) occurs due to antibodies active at body temperature that react with antigens on the surface of red blood cells, leading to hemolysis. Antibodies are typically IgG. WAIHA, associated exclusively with IgA antibodies, remains rare. Direct antiglobulin (Coombs) test may result negative in IgA antibody associated WAIHA. IgA-mediated WAIHA can present with severe hemolytic anemia. Further testing using an expanded direct antiglobulin test (DAT) panel is necessary to detect IgA antibodies if there is a high suspicion of autoimmune hemolytic anemia in cases that initially test negative for DAT. Steroids with or without rituximab are the mainstay of treatment. Early detection using an extended DAT panel with monospecific antisera helps avoid further investigations, unnecessary transfusions, and complications.

Autoimmune Hemolytic Anemias: Classifications, Pathophysiology, Diagnoses and Management

Autoimmune hemolytic anemias (AIHAs) are conditions involving the production of antibodies against one's own red blood cells (RBCs). These can be primary with unknown cause or secondary (by association with diseases or infections). There are several different categories of AIHAs recognized according to their features in the direct antiglobulin test (DAT). (1) Warm-antibody AIHA (wAIHA) exhibits a pan-reactive IgG autoantibody recognizing a portion of band 3 (wherein the DAT may be positive with IgG, C3d or both). Treatment involves glucocorticoids and steroid-sparing agents and may consider IVIG or monoclonal antibodies to CD20, CD38 or C1q. (2) Cold-antibody AIHA due to IgMs range from cold agglutinin syndrome (CAS) to cold agglutin disease (CAD). These are typically specific to the Ii blood group system, with the former (CAS) being polyclonal and the latter (CAD) being a more severe and monoclonal entity. The DAT in either case is positive only with C3d. Foundationally, the patient is kept warm, though treatment for significant complement-related outcomes may, therefore, capitalize on monoclonal options against C1q or C5. (3) Mixed AIHA, also called combined cold and warm AIHA, has a DAT positive for both IgG and C3d, with treatment approaches inclusive of those appropriate for wAIHA and cold AIHA. (4) Paroxysmal cold hemoglobinuria (PCH), also termed Donath-Landsteiner test-positive AIHA, has a DAT positive only for C3d, driven upstream by a biphasic cold-reactive IgG antibody recruiting complement. Although usually self-remitting, management may consider monoclonal antibodies to C1q or C5. (5) Direct antiglobulin test-negative AIHA (DAT-neg AIHA), due to IgG antibody below detection thresholds in the DAT, or by non-detected IgM or IgA antibodies, is managed as wAIHA. (6) Drug-induced immune hemolytic anemia (DIIHA) appears as wAIHA with DAT IgG and/or C3d. Some cases may resolve after ceasing the instigating drug. (7) Passenger lymphocyte syndrome, found after transplantation, is caused by B-cells transferred from an antigen-negative donor whose antibodies react with a recipient who produces antigen-positive RBCs. This comprehensive review will discuss in detail each of these AIHAs and provide information on diagnosis, pathophysiology and treatment modalities.

Erythrophagocytosis in autoimmune immunoglobulin A-mediated hemolysis

INTRODUCTION

Warm antibody-mediated autoimmune hemolysis (WAIHA) is most often due to immunoglobulin G (IgG) antibodies and is detected by direct antiglobulin test (DAT). However, about 10% cases of hemolytic anemia are DAT negative. Herein, we describe a patient with DAT-negative hemolytic anemia due to an anti-IgA antibody. We investigate if isolated IgA can promote erythrophagocytosis.

METHODS

We isolated patient and control IgA on Jacalin agarose. Isolated IgA was used to sensitize healthy ABO/Rh-matched donor red blood cells (RBC). Antibody binding was examined by flowcytometry. The effect of IgA on erythrophagocytosis was evaluated using Macrophage colony stimulating factor 1 (M-CSF)-differentiated autologous macrophages by Giemsa staining and immunofluorescence microscopy.

RESULTS

We show that isolated IgA from the serum can bind to red cells. In addition, RBCs were phagocytosed efficiently by autologous macrophages in the presence of patient IgA.

CONCLUSION

Our results show that IgA antibodies are capable of inducing erythrophagocytosis like IgG antibodies in the absence of complement fixation.

Comparison of the conventional tube and erythrocyte-magnetized technology in titration of red blood cell alloantibodies

BACKGROUND

Erythrocyte alloantibodies are mainly produced after immune stimulation, such as blood transfusion, pregnancy, and transplantation, and are the leading causes of severe hemolytic transfusion reactions and difficulty in blood grouping and matching. Therefore, antibody screening is critical to prevent and improve red cell alloantibodies. Routine tube assay is the primary detection method of antibody screening. Recently, erythrocyte-magnetized technology (EMT) has been increasingly used in clinical practice. This study intends to probe the application and efficacy of the conventional tube and EMT in red blood cell alloantibody titration to provide a reference for clinical blood transfusion.

AIM

To investigate the application value of conventional tube and EMT in red blood cell alloantibody titration and enhance the safety of blood transfusion practice.

METHODS

A total of 1298 blood samples were harvested from blood donors at the Department of Blood Transfusion of our hospital from March 2021 to December 2022. A 5 mL blood sample was collected in tubing, which was then cut, and the whole blood was put into a test tube for centrifugation to separate the serum. Different red blood cell blood group antibody titers were simultaneously detected using the tube polybrene test, tube antiglobulin test (AGT), and EMT screening irregular antibody methods to determine the best test method.

RESULTS

Simultaneous detection was performed through the tube polybrene test, tube AGT and EMT screening irregular antibodies. It was discovered that the EMT screening irregular antibody method could detect all immunoglobulin G (IgG) and immunoglobulin M (IgM) irregular antibodies, and the results of manual tube AGT were satisfactory, but the operation time was lengthy, and the equipment had a large footprint. The EMT screening irregular antibody assay was also conducted to determine its activity against type O Rh (D) red blood cells, and the outcomes were satisfactory. Furthermore, compared to the conventional tube method, the EMT screening irregular antibody method was more cost-effective and had significantly higher detection efficiency.

CONCLUSION

With a higher detection rate, the EMT screening irregular antibody method can detect both IgG and IgM irregular antibodies faster and more effectively than the conventional tube method.

Autoimmune Hemolytic Anemia in the Pediatric Age Group: The Egyptian Experience

Autoimmune hemolytic anemia (AIHA) is a common disease entity among adults; however, it is rare among the pediatric age group. Evidence is scarce regarding pediatric AIHA in the literature. The objective of this study is to assess the frequency of AIHA and describe the clinical and laboratory characteristics and treatment outcomes of a cohort of children with AIHA in Egypt. A retrospective study was conducted on 50 children with AIHA who were registered and followed up at the New Children's Hospital in Cairo, Egypt, between January 2010 and January 2021. The study group comprised 60% females and 40% males. Their median age was 8.25 years. All patients showed low hemoglobin levels with a mean of 5.40 ± 1.34 g/dl and a median reticulocyte count of 10 (IQR: 8-15). Twelve (24%) patients were diagnosed with Evans syndrome, and a positive Coombs test was detected in 46 patients (92%). The frequency of primary AIHA was 40%, whereas it was 60% for secondary AIHA. The first line of therapy for acute attacks was high-dose IV steroids which responded well in 38 (76%) patients. Secondary AIHA was more common among our children (60%). AIHA is more prevalent in females (60%). The clinical and laboratory characteristics matched previous reports.

Successful Treatment with Brigatinib after Alectinib-Induced Hemolytic Anemia in Patients with Metastatic Lung Adenocarcinoma-A Case Series

Alectinib is a second-generation anaplastic lymphoma kinase (ALK) inhibitor used in the treatment of advanced ALK-rearrangement positive non-small-cell lung cancer (NSCLC). Many tolerable adverse events were reported with the use of Alectinib; nevertheless, hemolytic anemia was not mentioned in the safety analysis. In this case, series, we report four cases of Alectinib-induced oxidative hemolytic anemia and discuss different etiologic hypotheses on the underlying mechanism of such overlooked adverse event of the drug. Furthermore, we draw attention to the successful treatment with Brigatinib, an alternative second-generation ALK-inhibitor without recurrence of hemolytic anemia in three of our four cases, suggesting a probable class effect.

Hemolytic Disease of the Newborn: A Community Hospitalist Perspective

Hemolytic disease of the newborn is commonly diagnosed and managed by pediatric and newborn hospitalists. Severe cases, however, pose unique challenges for community hospitals without higher level neonatal intensive care units. This case highlights the challenges faced by pediatric hospitalists in the community and suggests a focused approach to management.

Cytomegalovirus and Hemolytic Anemia in an Immunocompetent Adult

Hemolytic anemia is an increasingly recognized complication of cytomegalovirus (CMV) infection in immunocompetent patients. Although it is thought to be immune-mediated, other mechanisms have been proposed. The decision to treat is controversial but it may include antiviral and immunosuppressive therapy. We report a case of CMV-induced hemolytic anemia in a previously healthy 55-year-old woman. The patient presented with asthenia and choluria, and laboratory tests showed severe anemia with hyperbilirubinemia and elevated lactate dehydrogenase. A diagnosis of hemolytic anemia was made. Structural, enzymatic, toxic, pharmacological, and neoplastic causes were excluded. The CMV immunoglobulin M was positive, with a negative direct antiglobulin test. The patient had an improvement in clinical and laboratory status without any treatment, and two months later she had a full recovery of the anemia. This case illustrates that CMV infection might be associated with severe organ damage in immunocompetent patients but has an overall good prognosis without any directed treatment.

Severe hemolysis with negative direct antiglobulin test: A case report

A 49-year-old woman with type 2 diabetes mellitus (T2DM) presented to the emergency department. Her examination showed marked pallor, exhaustion, lethargy, yellowish eyes, anorexia, nausea and vomiting.

Hematuria; negative standard direct antiglobulin test (DAT); normal glucose 6 phosphate dehydrogenase (G6PD); hemoglobin (Hb), 4.8 g/dl; Mean cell volume (MCV), 91fl; platelet count, 233 × 10⁶/L; Total bilirubin, 7.0 mg/dl; Glucose, 316 mg/dl; lactate dehydrogenase (LDH), 1750U/L. Undoubtedly, therapeutic panel should have been used for hemolytic anemia. Intravenous (IV) fluids and 2 units of packed cell were transfused. Methylprednisolone with rituximab were started for the patient. After 3 weeks of the patient admission, she was discharged home with stable vital signs and Hb, 10 g/dl. We concluded in the cases that presented along with a severe drop in Hb and evidence of hemolysis which non immune hemolytic anemia is excluded in spite of negative standard DAT limited transfusion besides corticosteroids combined with rituximab, could be helpful in saving the patient.

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Autoimmune hemolytic anemia (AIHA) is caused by increased erythrocyte destruction with autoantibodies directed against the person's own red blood cells and susceptible them to lyse and consequent insufficient number of red blood cells in the circulation.

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A diagnosis of DAT-negative AIHA can be made following careful exclusion of alternative causes of hemolysis, and confirmation by a sensitive technique and by a response to steroid therapy.

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.

A Curious Case of Hemolytic Anemia with Pseudoreticulopenia

Herein, we present a unique case of a Coombs-negative, steroid-refractory autoimmune hemolytic anemia (AIHA) complicated by pseudoreticulopenia, describe its clinical presentation, histopathologic findings, and management, and review the salient literature. Coombs-negative, steroid-refractory AIHAs represent fewer than 1% of all AIHAs. Diagnosis of the disease is difficult and often delayed due to the pursuit of alternate diagnoses following a negative Coombs test. However, when suspicion remains high for an autoimmune process, the super-Coombs test may be utilized for the diagnosis of AIHA that the traditional Coombs test fails to detect. A majority of cases respond to rituximab as the indicated second-line therapy, but delays in diagnosis and subsequent treatment may increase morbidity. Reticulopenia may be associated with AIHAs secondary to bone marrow dysfunction, but this patient had a normal function marrow confirmed on biopsy. Indeed, reticulopenia in this case was a diagnostic conundrum that further obscured the diagnosis and delayed treatment. Ultimately, reticulopenia was determined to be pseudoreticulopenia secondary to an alteration in the maturation of the erythroid lineage due to an independent, newly diagnosed pernicious anemia. The interaction of these multiple coexisting disease processes is not previously described in the literature. Increased physician awareness of steroid-refractory, Coombs-negative AIHA, and the development of pseudoreticulopenia as a laboratory finding in pernicious anemia may help to improve patient outcomes.

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.

IgM Warm Autoantibodies Causing Autoimmune Hemolytic Anemia in a Pediatric Patient

Most often, IgM-mediated autoimmune hemolytic anemia (AIHA) presents as cold agglutinin disease in the pediatric population. The IgM warm agglutinins are rare, with few reports in the literature. This case study describes a 5 year old girl with nausea, abdominal pain and jaundice, and a hemoglobin of 5.5 g/dL who was diagnosed with a warm reactive IgM AIHA. The laboratory workup revealed a pan-reactive antibody and a direct antiglobulin test negative for IgG and C3. A thermal amplitude assay revealed reactive IgM antibodies at 37°C, 30°C, 25°C, and 4°C and an antibody titer of 1:8. An adsorption for IgM-specific autoantibodies exposed underlying anti-E and anti-Cw alloantibodies. Transfusion of phenotypically matched red blood cell units supported ongoing hemolysis. The AIHA treatment included steroids followed by rituximab with complete resolution. A literature review shows variable outcomes for warm AIHA in the pediatric population and often describes the presence of warm reactive IgM-mediated AIHA as an indicator for poor prognosis.

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.

Comparative study of immunohematological tests with canine blood samples submitted for a direct antiglobulin (Coombs') test

BACKGROUND

A 2019 ACVIM consensus statement on diagnostics for immune-mediated hemolytic anemia (IMHA) in dogs made testing recommendations. As data on the performance of immunohematological tests was lacking, we undertook a comparative analysis.

MATERIAL AND METHODS

Anticoagulated blood samples from 126 dogs suspected of having IMHA submitted to a diagnostic veterinary laboratory for a routine direct antiglobulin test (DAT) and from 28 healthy control dogs were evaluated for spherocytosis and autoagglutination before and after three saline washes. Samples were also subjected to different DATs: a gel minitube and an immunochromatographic strip kit used in clinics; neutral gel column cards, microtiter plates (at 4°, 22°, and 37°C), capillary tubes, and flow cytometry used in laboratories.

RESULTS

Samples from healthy dogs yielded negative results with all immunodiagnostic tests. Among the 126 samples submitted for DAT 67 were positive by a DAT utilizing microtiter plates with goat anti-dog antiglobulin DAT at 22°C. Notably, DAT results were comparable and consistent across all evaluated methods regardless of antiglobulin and temperature used. DAT+ dogs were more severely anemic and more likely to have erythroid regeneration compared to DAT- dogs. Macroscopic agglutination in tubes or on slides was observed in 48 samples after 1:1 and 1:4 blood to saline dilution, but only persisted in four samples after washing. Among the DAT+ samples, 57% had agglutination, 87% had spherocytosis, and 45% had both. There was good correlation between spherocytosis and DAT results from the six DAT techniques, but the correlation with autoagglutination was only fair. Clinical follow-up was available for 42 dogs. Of the sample from 12 DAT+ dogs collected during treatment, 10 remained DAT+ when tested 1-24 weeks after initial assessment.

CONCLUSIONS

Based upon this comparative prospective survey, all in-clinic and laboratory DAT techniques produced similar results when performed by trained personnel and can therefore be recommended for detection of antibody-coated erythrocytes and immunohematological diagnosis. In addition, use of these tests for monitoring response of IMHA dogs to treatment might be valuable.

Comparison between the Manual Method of Indirect Coombs via Gel Technology and Solid Phase Red Cell Adherence

Objective: An experiment was conducted to define the principle of the conventional tube technique, gel card technology, and solid-phase technology of blood transfusion. The study also highlights the test reactions and various methods of grading reactions for each technology. It further discusses the automated equipment available for each technology and compares the equipment, tests reactions, procedures, and sensitivity of these techniques. Material and methods: This cross-sectional study was conducted on blood samples of 40 patients with positive indirect antiglobulin test at the Padmashree Diagnostics Center and the Bangalore Medical Services Trust, India. Tube and gel card method and solid-phase red cell adherence assay (SPRCA) were evaluated. Results: The results revealed SRPCA of 1+ in nine samples, 2+ in 15 samples, 3+ in 13 samples and 4+ in three samples, while the manual method yielded 1+ in 14 samples, 2+ in 13 samples, 3+ in 13 samples and 4+ in one sample. Conclusion: Solid-phase red cell adherence assay is more precise and capable of detecting red cell adherence assay than tube method and indirect Coombs test gel technology.

Pembrolizumab-induced autoimmune haemolytic anemia in a patient with chronic lymphocytic leukaemia successfully treated with ibrutinib

We present a unique case of a patient with a long-standing history of indolent chronic lymphocytic leukaemia (CLL) who suddenly developed autoimmune haemolytic anaemia after starting immune checkpoint inhibitor therapy for bladder cancer. He had no clear indication to start CLL-directed treatment based on current clinical practice guidelines; however, targeted treatment of CLL with ibrutinib proved to be effective in treating the haemolytic anaemia.

Post-transfusion hyperhemolysis syndrome in a patient with beta thalassemia major

Hyperhemolysis syndrome (HS) is characterized by the occurrence of severe anemia with post-transfusion hemoglobin and hematocrit levels being markedly lower than those present prior to transfusion. A high index of suspicion of HS in a multi-transfused thalassemia patient allows prompt institution of therapy resulting in improved survival outcome.

Immune cytopenia after allogeneic haematopoietic stem-cell transplantation: challenges, approaches, and future directions

Immune-mediated cytopenia after allogeneic haematopoietic stem-cell transplantation is rare. The pathophysiology of immune-mediated anaemia, thrombocytopenia, and neutropenia, which occur alone or in combination with other cytopenias, is unclear and most probably a consequence of immune dysregulation. Risk factors for this complication have been identified in retrospective studies but these should be interpreted with caution and should not be generalised to this heterogeneous patient population. Diagnosis is challenging, requires awareness of such complications, and has to be differentiated from a multitude of other, and sometimes overlapping, possible complications. The clinical course of immune-mediated cytopenia is highly variable. Treatment requires an interdisciplinary approach and ranges from observation to symptomatic measures and directed therapies. Intensive immunosuppression is associated with an increased risk of infections and relapse, and current treatments are based on approaches in patients who have not undergone transplantation. Plasma cell-directed therapies, immunomodulation, and receptor-stimulating agents can be used to treat immune-mediated cytopenia.

A renewed understanding of anti-human globulin reagents: interference constraints using an optimization method in pretransfusion compatibility tests

Anti‐human globulin (AHG) reagents are widely applied in pretransfusion compatibility tests. The accuracy of detection with AHG reagents is mainly affected by irregular antibodies or cold agglutinins in blood samples, which are related to the human complement system. Although much has been written about various types and applications of AHG reagents, their characteristics, interference factors and optimal selection in pretransfusion compatibility tests still need to be further clarified. Here, we review clinical practice and basic studies that describe each AHG reagent, summarize the advantages and disadvantages of using different AHG reagents in the presence of cold agglutinins or complement‐fixing antibodies, explore the potential mechanisms by which the complement system influences detection with AHG reagents and address the question of how to optimally select AHG reagents for clinically significant antibody detection.

Autoimmune Hemolytic Anemia in the Pediatric Setting

Autoimmune hemolytic anemia (AIHA) is a rare disease in children, presenting with variable severity. Most commonly, warm-reactive IgG antibodies bind erythrocytes at 37 °C and induce opsonization and phagocytosis mainly by the splenic macrophages, causing warm AIHA (w-AIHA). Post-infectious cold-reactive antibodies can also lead to hemolysis following the patient’s exposure to cold temperatures, causing cold agglutinin syndrome (CAS) due to IgM autoantibodies, or paroxysmal cold hemoglobinuria (PCH) due to atypical IgG autoantibodies which bind their target RBC antigen and fix complement at 4 °C. Cold-reactive antibodies mainly induce intravascular hemolysis after complement activation. Direct antiglobulin test (DAT) is the gold standard for AIHA diagnosis; however, DAT negative results are seen in up to 11% of warm AIHA, highlighting the need to pursue further evaluation in cases with a phenotype compatible with immune-mediated hemolytic anemia despite negative DAT. Prompt supportive care, initiation of treatment with steroids for w-AIHA, and transfusion if necessary for symptomatic or fast-evolving anemia is crucial for a positive outcome. w-AIHA in children is often secondary to underlying immune dysregulation syndromes and thus, screening for such disorders is recommended at presentation, before initiating treatment with immunosuppressants, to determine prognosis and optimize long-term management potentially with novel targeted medications.

A rare haematological disorder in a Sudanese child: Evans syndrome, case report and literature review

Evans syndrome is a condition in which autoimmune-mediated red blood cells and platelet destruction happens consecutively. It may be associated with a reduction in neutrophil count as a result of immune neutropenia. No sex preference is known and it presents in all ages and any ethnic cohort. Generally, this syndrome tends to be chronic and is characterised by remission and exacerbation. We document a case of the immune-mediated disease associated with Epstein-Barr virus infection in an 8-year-old boy from eastern Sudan who presented with both immune thrombocytopenia purpura and autoimmune haemolytic anaemia. Complete blood count and peripheral blood picture revealed features consistent with immune haemolytic anaemia (rouleaux formation and spherocytes) and thrombocytopenia. Direct anti-human globulin test and indirect anti-human globulin test were positive. Evans syndrome is a potentially life-threatening condition due to the concomitant existence with antiplatelet and anti-erythrocyte antibodies distinguished by a positive antiglobulin test and possibly linked to other autoimmune or lymphoproliferative diseases.

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.

Diagnosis and management of autoimmune hemolytic anemia in children

BACKGROUND AND AIM

The aim of this study is to evaluate the clinical, biological and hematological profiles of autoimmune hemolytic anemia (AIHA) in children and to specify its etiologies, therapeutic modalities, and treatment responses.

METHODS

This is a 14-year retrospective study of AIHA cases collected at the department of pediatric emergency and reanimation of Hedi Chaker University Hospital in Sfax. We included patients under 14 years old with clinical and biological features of hemolysis and a positive direct antiglobulin test (DAT). The selected patients' demographic characteristics, physical signs, laboratory findings, and treatment responses were recorded.

RESULTS

Thirteen cases of AIHA were collected, including 8 girls and 5 boys. The median age at diagnosis was 4 years and 6 months (range: 8 months to 13 years). Consanguinity was reported in 6 cases and 4 patients had a previous infection history. The onset of AIHA was progressive in 9 cases, marked by an anemic syndrome and hemolysis symptoms in 6 and 8 cases, respectively. The clinical triad (pallor, jaundice and splenomegaly) was found in only 4 cases. At the time of diagnosis, the median hemoglobin (Hb) level was 6g/dL (range: 4.2 to 9.2g/dL), anemia was non-regenerative in 2 patients. Thrombocytopenia and neutropenia were noted in 5 and 1 patient, respectively. Peripheral smear examination showed spherocytosis in 2 cases. All the patients had a positive DAT. Of these, 10 were positive with IgG and 3 with both IgG and C3d. AIHA was secondary to other conditions in 9 patients: infection (3 cases), autoimmune disease (4 cases), and immunodeficiency (2 cases). All the patients received first-line corticosteroid therapy but only 8 of them required blood transfusions due to severe anemia. Complete remission was obtained in 7 cases. Corticosteroid resistance and dependence were noted in 1 and 2 cases, respectively. During evolution, additional therapy was indicated in 4 patients and it included cyclosporine A, azathioprine, and mycophenolate mofetil (MMF). After a median follow-up of 4.5 years, the cure rate was 80% and only 1 patient (a boy) died due to his underlying pathology.

CONCLUSION

Our study highlights the rarity, severity, and heterogeneity of etiological contexts of AIHA in children. The therapeutic difficulties justify specific expertise in pediatric hematology.

IgA-mediated autoimmune hemolytic anemia in an infant

Autoimmune Hemolytic anemia (AIHA) a relatively uncommon form of hemolytic anemia in children, occurs due to the premature destruction of red blood cells caused by presence of autoantibodies directed against antigens on RBCs. Warm reactive AIHA is the most common form due to IgG isotype of immunoglobulin class binding to autologous RBCs at 37⁰C and confirmed with a positive DAT screening. We present a case of DAT-negative primary warm AIHA in an infant due to IgA antibody. A 10 month old male infant presented with dark colored urine and irritability for past two months, with associated history of fever, diarrhea and vomiting. He had received one red cell transfusion 10 days prior. On physical examination he had pallor with tachycardia without splenomegaly. On investigation his hemoglobin was 5.8 g/dl, WBC 25.9 × 10³/mm³ and normal platelets counts. Peripheral blood smear had spherocytes and biochemical values showed high bilirubin and LDH. Immunohematological work up revelaed polyspecific DAT was negative but monospecific DAT screening showed strong (4+) positivity for IgA and a weak IgG positivity. The patient was diagnosed as IgA-mediated Warm AIHA and was started on prednisolone at 2 mg/kg/day following which hemoglobin improved over the next 2 months. After 2 weeks, prednisolone was tapered and stopped by the end of 3 months. Patients with clinical and laboratory evidence of acute hemolysis, an additional screening for IgA antibody may be done even in cases where poly-specific DAT is negative. Early detection helps in avoiding further investigations and provide efficient management.

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.

A case-control analysis of hyperhemolysis syndrome in adults and laboratory correlates of complement involvement

BACKGROUND

Hyperhemolysis syndrome (HS) is a poorly understood, severe hemolytic anemia provoked by transfusion. Both host and donor RBCs are destroyed in HS; thus, transfusion paradoxically worsens anemia. Risk factors and mechanism of HS are unknown.

STUDY DESIGN AND METHODS

A retrospective case-control analysis was performed on adults with HS. Patients with HS were matched 1:1 with matched, transfused controls, and HS risk factors were analyzed with multivariable logistic regression. HS samples were analyzed for complement deposition by flow cytometry, and an in vitro model of bystander hemolysis was developed.

RESULTS

Forty-one patients with 54 episodes of HS were identified in a 26-year period from 1992 to 2018. Of the HS episodes, only 18.5% were associated with a new alloantibody, and such patients were more tolerant of additional transfusion in the acute episode (p = 0.005). Thirteen percent of episodes were fatal, and HS recurred in 52.6%. Alloimmunization (odds ratio [OR], 17.3), non-B blood type (OR, 9.8), D antigen (OR, 9.1), and infection (OR, 5.5) were associated with HS on multivariable analysis. Hyperbilirubinemia was predictive of fatal HS (OR, 33.6). Increased complement was observed on RBCs during HS episodes, and the in vitro model of bystander hemolysis recapitulated complement decoration of sickled RBCs.

CONCLUSIONS

HS is associated with significant morbidity, mortality, and recurrence. Risk factors such as known alloimmunization, blood group, and infection predispose to HS. Bystander complement activation may drive HS. These factors may help physicians refine risk-benefit assessments for transfusion and guide further therapeutic development.

The chemical and laboratory investigation of hemolysis

The abnormal breakdown of circulating red blood cells (RBCs), also known as hemolysis, is a significant clinical issue that can present as a primary disorder or arise secondary to another disease process. The evaluation for pathologic hemolysis (and the establishment of a hemolytic disorder) is heavily dependent on assays performed and overseen by the divisions of Hematology, Blood Bank/Transfusion Medicine, Clinical Chemistry, and Immunology in the clinical laboratory. Because of the wide variety of assays used across the spectrum of clinical pathology and potential pitfalls/limitations associated with this testing, the decision of which assay to choose and, perhaps more importantly, how to interpret results, can both be quite challenging. Thus, the aim of this manuscript is to provide a comprehensive review on the laboratory investigation of pathologic forms of hemolysis and hemolytic disorders. This chapter will: (1) introduce basic concepts on the pathophysiology of hemolysis and (2) examine assays available for hemolysis on a laboratory-by-laboratory basis, with a particular emphasis on the strengths, limitations, and clinical interpretations of each of these assays.

Clinical and laboratory features of autoimmune hemolytic anemia associated with immune checkpoint inhibitors

Immune checkpoint inhibitors (ICPis) are a novel class of immunotherapeutic agents that have revolutionized the treatment of cancer; however, these drugs can also cause a unique spectrum of autoimmune toxicity. Autoimmune hemolytic anemia (AIHA) is a rare, but often severe, complication of ICPis. We identified 14 patients from nine institutions across the United States who developed ICPi-AIHA. The median interval from ICPi initiation to development of AIHA was 55 days (interquartile range [IQR], 22-110 days). Results from the direct antiglobulin test (DAT) were available for 13 of 14 patients: 8 patients (62%) had a positive DAT and 5 (38%) had a negative DAT. The median pretreatment and nadir hemoglobin concentrations were 11.8 g/dL (IQR, 10.2-12.9 g/dL) and 6.3 g/dL (IQR, 6.1-8.0 g/dL), respectively. Four patients (29%) had a preexisting lymphoproliferative disorder, and two (14%) had a positive DAT prior to initiation of ICPi therapy. All patients were treated with glucocorticoids, with three requiring additional immunosuppressive therapy. Complete and partial recoveries of hemoglobin were achieved in 12 (86%) and 2 (14%) patients, respectively. Seven patients (50%) were rechallenged with ICPis, and one (14%) developed recurrent AIHA. Clinical and laboratory features of ICPi-AIHA were similar in DAT positive and negative patients. ICPi-AIHA shares many clinical features with primary AIHA; however, a unique aspect of ICPi-AIHA is a high incidence of DAT negativity. Glucocorticoids are an effective first-line treatment in the majority of patients with ICPi-AIHA, and most patients who are rechallenged with an ICPi do not appear to develop recurrence of AIHA.

Acute Retroviral Syndrome Presenting with Hemolytic Anemia Induced by G6PD Deficiency

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common enzyme defect described in humans. Hemolysis in affected patients is usually triggered by circumstances involving free radical damage. While acute HIV infection is known to be a state of overwhelming oxidative stress, virus-induced hemolytic events in G6PD-deficient patients has rarely been reported. Despite an estimated overall prevalence of 6.8%⁻13% of this disorder in the HIV population, clinically significant hemolysis has been largely attributed to the use of offending medications rather than HIV infection itself. Here, we present a patient whose first episode of G6PD deficiency-associated hemolysis occurred as the main presentation of acute HIV infection.

Autoimmune haemolytic anaemia associated with P. vivax malaria

Autoimmune haemolytic anaemia due to malaria or following its treatment with artesunate is rare. A child presented with severe anaemia after being treated with artesunate for P. vivax malaria. Blood transfusion was difficult as cross-matching showed major incompatibility; group O negative blood under the cover of steroids was transfused. Oral steroids were given for six weeks. The patient made a complete recovery.

Features of peripheral CD8+CD57+ lymphocytes in patients with autoimmune hemolytic anemia

Autoimmune hemolytic anemia (AIHA) is an acquired condition characterized by the presence of autoantibodies recognizing erythrocyte-related antigens. Several components of the immune system are involved in disease pathogenesis. Among them, as for other autoimmune disorders, a role for specific CD8⁺CD57⁺ regulatory cells subset could be hypothesized. We evaluated this lymphocyte subset by flow cytometry in 18 AIHA patients randomly selected in a retrospective population of 29 cases. Secondary forms were observed in 65.5% of cases, whereas frequencies of warm, cold, mixed, and atypical forms were similar. Cold agglutinins and cryoglobulins tested positive in 44.8% and 10.3% of cases, respectively. These patients exhibited a higher frequency of peripheral vascular symptoms (odds ratio = 8.2, p = .04) and complement consumption (odds ratio = 7.2, p = .02). Frequency of CD8⁺CD57⁺ cells resulted significantly higher in AIHA patients than in control group (17.0 ± 15.8% vs 8.2 ± 5.0%, p = .04). Regardless of therapeutic schedule, patients with partial or no response to therapy (8/18) showed higher frequencies of CD8⁺CD57⁺ cells as compared with controls (23.6 ± 21.3% vs 8.9 ± 4.9%, p = .01), whereas 10/18 complete responders (CR) showed lower levels of CD8⁺CD57⁺ cells (11.7 ± 6.9%, p = .11). CR and controls showed similar values (p = .24). This study suggests that monitoring this lymphocyte subset before and after treatment administration might have a prognostic value. Moreover, CD8⁺CD57⁺ cells may represent a possible therapeutic target to restore the normal balance between lymphocyte populations.