Delayed hemolytic transfusion reaction/hyperhemolysis syndrome in children with sickle cell disease

Prevention of potential delayed hemolytic transfusion reaction in two sickle cell patients using intravenous immunoglobulins and steroids before and after red blood cell exchange with antigen positive units and review literature

Emergent Red Blood Cell (RBC) exchange is indicated in sickle cell disease (SCD) patients with severe acute chest syndrome. However, fully matched RBC units may not be available for patients with multiple RBC antibodies. Intravenous immunoglobulin (IVIG) and steroids were reported for preventing potential delayed hemolytic transfusion reaction (HTR) in simple transfusion of antigen-positive RBCs. We investigated the efficacy and safety of IVIG and steroids in two SCD patients presented with acute chest syndrome receiving RBC exchange with multiple incompatible units. The first patient had multiple historical alloantibodies, including anti-Jsb, although none of them were reactive. IVIG (1 g/kg) was given before and after RBC exchange with methylprednisolone (500 mg IV) one hour before exchange. Her sickle hemoglobin (HbS) was reduced from 89.4% to 17.4% after the exchange with five Jsb-positive units. The patient improved clinically without acute or delayed hemolysis. The second patient had reactive anti-Jsb on two different admissions 18 months apart. Only one of the sixteen units used in the exchanges was Jsb negative. He received the same IVIG regimen during both admissions but 100 mg IV hydrocortisone instead of methylprednisolone. His HbS was reduced from 63.4% to 22.4% after the first exchange. Significant clinical improvements were achieved after both exchanges. No delayed HTR was observed. Our experience of these two patients suggested that IVIG and steroids may be used in preventing potential delayed HTR in some SCD patients with rare antibodies receiving large amounts of antigen-positive RBC products.

What is the role of complement in bystander hemolysis? Old concept, new insights

INTRODUCTION

Bystander hemolysis occurs when antigen-negative red blood cells (RBCs) are lysed by the complement system. Many clinical entities including passenger lymphocyte syndrome, hyperhemolysis following blood transfusion, and paroxysmal nocturnal hemoglobinuria are complicated by bystander hemolysis.

AREAS COVERED

The review provides data about the role of the complement system in the pathogenesis of bystander hemolysis. Moreover, future perspectives on the understanding and management of this syndrome are described.

EXPERT OPINION

Complement system can be activated via classical, alternative, and lectin pathways. Classical pathway activation is mediated by antigen-antibody (autoantibodies and alloantibodies against autologous RBCs, infectious agents) complexes. Alternative pathway initiation is triggered by heme, RBC microvesicles, and endothelial injury that is a result of intravascular hemolysis. Thus, C5b is formed, binds with C6-C9 compomers, and MAC (C5b-9) is formulated in bystander RBCs membranes, leading to cell lysis. Intravascular hemolysis, results in activation of the alternative pathway, establishing a vicious cycle between complement activation and bystander hemolysis. C5 inhibitors have been used effectively in patients with hyperhemolysis syndrome and other entities characterized by bystander hemolysis.

Immune-Mediated Hemolytic Anemia and Clinically Suspected Acute Pancreatitis in Dogs, a Pilot Study

Acute pancreatitis can be a complication of massive hemolysis, above all when intravascular in nature. Therefore, the aim of this study was to investigate the association between canine immune mediated hemolytic anemia (IMHA) and clinically suspected acute pancreatitis (CSAP) and the role of calculated free plasma hemoglobin (Hbfp) in CSAP occurrence/development. In this cohort study the records of 95 dogs with IMHA and 95 sick dogs with pathologies other than IMHA were compared for CSAP occurrence/development. At presentation, 12/95 dogs with IMHA met criteria for CSAP, while only 3/95 sick control dogs met these criteria (χ2 =1.58, P = .008). Within 7 days of hospitalization 9 additional dogs with IMHA had developed CSAP. The Hbfp was calculated and compared for dogs with IMHA that had/developed CSAP and for those without CSAP. In dogs with IMHA, a calculated Hbfp concentration ≥ 0.08 g/dL resulted in an increased relative risk (RR) of having/developing CSAP (RR = 2.54, 95% CI, 1.51-4.29; P = .003). No significant effect on short-term prognosis in dogs with IMHA was found between those having/developing CSAP and those without CSAP. This study showed that dogs with IMHA have an increased risk of having CSAP and Hbfp concentration may be involved in the pathogenesis of acute pancreatitis.

Variant RHD alleles and Rh immunization in patients with sickle cell disease

RH diversity among patients and donors contributes to Rh immunization despite serologic Rh-matched red cell transfusions. Anti-D can occur in D+ patients with RHD variants that encode partial D antigens. Anti-D has also been reported in patients with conventional RHD transfused primarily with units from Black donors who frequently have variant RHD. We report 48 anti-D in 690 D+ transfused individuals with sickle cell disease, categorized here as expressing conventional D, partial D or D antigen encoded by RHD*DAU0. Anti-D formed in a greater proportion of individuals with partial D, occurred after fewer D+ unit exposures, and remained detectable for longer than for those in the other categories. Among all anti-D, 13 had clinical or laboratory evidence of poor transfused red cell survival. Most individuals with anti-D were chronically transfused, including 32 with conventional RHD who required an average of 62 D- units/year following anti-D. Our findings suggest that patients with partial D may benefit from prophylactic D- or RH genotype-matched transfusions to prevent anti-D. Future studies should investigate whether RH genotype-matched transfusions can improve use of valuable donations from Black donors, reduce D immunization and minimize transfusion of D- units to D+ individuals with conventional RHD or DAU0 alleles.

Managing the Cerebrovascular Complications of Sickle Cell Disease: Current Perspectives

The importance of protecting brain function for people with sickle cell disease (SCD) cannot be overstated. SCD is associated with multiple cerebrovascular complications that threaten neurocognitive function and life. Without screening and preventive management, 11% of children at 24% of adults with SCD have ischemic or hemorrhagic strokes. Stroke screening in children with SCD is well-established using transcranial Doppler ultrasound (TCD). TCD velocities above 200 cm/s significantly increase the risk of stroke, which can be prevented using chronic red blood cell (RBC) transfusion. RBC transfusion is also the cornerstone of acute stroke management and secondary stroke prevention. Chronic transfusion requires long-term management of complications like iron overload. Hydroxyurea can replace chronic transfusions for primary stroke prevention in a select group of patients or in populations where chronic transfusions are not feasible. Silent cerebral infarction (SCI) is even more common than stroke, affecting 39% of children and more than 50% of adults with SCD; management of SCI is individualized and includes careful neurocognitive evaluation. Hematopoietic stem cell transplant prevents cerebrovascular complications, despite the short- and long-term risks. Newer disease-modifying agents like voxelotor and crizanlizumab, as well as gene therapy, may treat cerebrovascular complications, but these approaches are investigational.

Delayed haemolytic transfusion reaction in paediatric patients with sickle cell disease: A retrospective study in a French national reference centre

Delayed haemolytic transfusion reaction (DHTR) is a life-threatening haemolytic anaemia following red blood cell transfusion in patients with sickle cell disease, with only scarce data in children. We retrospectively analysed 41 cases of DHTR in children treated between 2006 and 2020 in a French university hospital. DHTR manifested at a median age of 10.5 years, symptoms occurred a median of 8 days after transfusion performed for an acute event (63%), before surgery (20%) or in a chronic transfusion programme (17%). In all, 93% of patients had painful crisis. Profound anaemia (median 49 g/L), low reticulocyte count (median 140 ×10⁹ /L) and increased lactate dehydrogenase (median 2239 IU/L) were observed. Antibody screening was positive in 51% of patients, and more frequent when there was a history of alloimmunisation. Although no deaths were reported, significant complications occurred in 51% of patients: acute chest syndrome (12 patients), cholestasis (five patients), stroke (two patients) and kidney failure (two patients). A further transfusion was required in 23 patients and corticosteroids were used in 21 to reduce the risk of additional haemolysis. In all, 13 patients subsequently received further transfusions with recurrence of DHTR in only two. The study affords a better overview of DHTR and highlights the need to establish guidelines for its management in children.

Adverse events of red blood cell transfusions in patients with sickle cell disease

Blood transfusion is a common medical intervention for patients with sickle cell disease (SCD) and disease related complications. While patients with SCD are at risk for all transfusion related adverse events defined by the National Healthcare Safety Network (NHSN) Biovigilance Component Hemovigilance Module Surveillance Protocol, they are uniquely susceptible to certain adverse events. This review discusses risk factors, mitigation strategies, and management recommendations for alloimmunization, hemolytic transfusion reactions, hyperviscosity and transfusion-associated iron overload in the context of SCD.

Preoperative Transfusion and Surgical Outcomes for Children with Sickle Cell Disease

BACKGROUND

Current guidelines recommending preoperative transfusion to a hemoglobin level of 9 to 10 g/dL for patients with sickle cell disease (SCD) are based on imperfect evidence. The benefit of preoperative transfusion in children specifically is not known. This study aimed to evaluate whether preoperative RBC transfusion is associated with different rates of sickle cell crisis and surgical complications, compared with no preoperative transfusion, among children with SCD undergoing common abdominal operations.

STUDY DESIGN

The NSQIP-Pediatrics database (2013 to 2019) was queried. Patients who underwent cholecystectomy, splenectomy, or appendectomy with a preoperative Hct level of less than 30% were included. The primary outcome was 30-day readmission for sickle cell crisis. Secondary outcomes were 30-day surgical complications and hospital length of stay. Propensity score matching methods were used to obtain two statistically similar cohorts of patients comprised of those who were preoperatively transfused and those who were not.

RESULTS

Among 357 SCD patients, 200 (56%) received preoperative transfusion. In the matched cohort of 278 patients (139 per group), there was no statistically significant difference in 30-day readmission for sickle cell crisis in the transfused and non-transfused groups (5.8% vs 7.2%, p = 0.80). The rate of 30-day surgical complications did not differ between matched groups (10.8% vs 9.4%, p = 0.84). Subgroups defined by presenting Hct levels of 27.3% or greater or less than 27.3%, American Society of Anesthesiologists classification, wound class, and index operation were not associated with an altered risk of sickle cell crisis or surgical complications after preoperative transfusion compared with no transfusion.

CONCLUSIONS

Preoperative transfusion for children with SCD undergoing semi-elective abdominal operations was not associated with improved outcomes. Prospective investigation is warranted to strengthen guidelines and minimize unnecessary perioperative transfusions in this population.

Acute Hyperhemolysis Syndrome in a Patient with Known Sickle Cell Anemia Refractory to Steroids and IVIG Treated with Tocilizumab and Erythropoietin: A Case Report and Review of Literature

Patients with sickle cell anemia often receive multiple red blood cell (RBC) transfusions during their lifetime. Hyperhemolysis is a life-threatening phenomenon of accelerated hemolysis and worsening anemia that occurs when both transfused RBCs and autologous RBCs are destroyed. The level of hemoglobin post-transfusion is lower than pre-transfusion levels, and patients are usually hemodynamically unstable. Hyperhemolysis must be differentiated from a delayed hemolytic transfusion reaction during which destruction of transfused RBC is the cause of anemia. Hyperhemolysis syndrome can be differentiated into acute (within seven days) and chronic forms (after seven days) post-transfusion. The authors present a case of acute hyperhemolysis syndrome in a patient with sickle cell anemia refractory to steroids and IVIG, which are the treatment of choice. The patient was treated with tocilizumab, combined with supportive measures of erythropoietin, iron, vitamin B12, and folate.

Preventing antibody positive delayed hemolytic transfusion reactions in sickle cell disease: Lessons learned from a case

INTRODUCTION

Red blood cell (RBC) transfusions are important in the management of patients with sickle cell disease (SCD). However, a potentially catastrophic complication of transfusion in this population is the delayed hemolytic transfusion reaction (DHTR). The pathophysiology of all DHTRs is not understood, but some are known to be caused by an anamnestic resurgence of RBC alloantibodies.

CASE PRESENTATION

A child with SCD transfused for acute chest syndrome re-presented a week after hospital discharge with severe anaemia, hemolysis, and a newly detected anti-E. This patient had been previously transfused years ago at an outside institution and the anti-E had not been previously documented.

DISCUSSION

The presented case of an antibody positive DHTR illustrates several concepts critical to the prevention of this complication. RBC alloantibodies must be detected and this information must be shared. Prophylactic C/c, E/e, K antigen matching is helpful for patients with SCD, but systems must be in place to identify these patients. Patients transfused at multiple different hospitals are especially at risk for this complication and efforts are needed to prevent them from suffering a DHTR.

A Case Study in Process Improvement to Minimize Delays from Obtaining Blood for Red Cell Exchange for a Patient with Sickle Cell Disease and Multiple Red Blood Cell Alloantibodies

The process of procuring several units of red blood cells for red cell exchange can sometimes take several hours to days, especially for patients with multiple clinically significant red cell alloantibodies. This can introduce delays, inconveniences, and even health challenges for the patient. For most planned exchanges, these delays are preventable with some foresight and process modifications that are relatively minor yet high leverage. We report a case study of process improvement whereby the apheresis nurse sends an e-mail to the blood bank when the nurse makes the patient's next red cell exchange appointment as the signal to order blood about 6–8 weeks before the exchange.

Eculizumab as a Treatment for Hyper-Haemolytic and Aplastic Crisis in Sickle Cell Disease

Background

Patients with sickle cell disease can experience various crises including sequestration crisis, haemolytic crisis and aplastic crisis. Due to alloantibody formation, transfusion alloantibodies can cause a haemolytic crisis. Treatment involves avoiding packed red blood cell transfusions, as well as intravenous immunoglobulin, steroids and eculizumab to decrease the chances of haemolysis.

Case description

We report the case of a 42-year-old man who was found to have worsening anaemia after packed red blood cell transfusion with evidence suggestive of haemolytic crisis. Due to reticulocytopenia, aplastic crisis was also suspected and later confirmed via parvovirus IgG and IgM titres. The patient did not improve with steroid and intravenous immunoglobulin therapy and was treated with eculizumab as a salvage therapy.

Conclusion

Concurrent hyper-haemolytic crisis and aplastic crisis should be suspected in patients with features of haemolysis and reticulocytopenia. Prompt recognition and treatment with eculizumab are paramount in those who fail steroid and intravenous immunoglobulin treatment.

LEARNING POINTS

Treatment of hyper-haemolytic and aplastic crisis in sickle cell disease with eculizumab offers therapeutic benefit.A high index of suspicion for hyper-haemolytic crisis and aplastic crisis should be maintained in those with haemolytic features as well as reticulocytopenia in the setting of sickle cell disease.

Extended phenotyping does not preclude the occurrence of delayed haemolytic transfusion reactions in sickle cell disease

Delayed haemolytic transfusion reaction (DHTR) is a potentially life-threatening complication of red blood cell (RBC) transfusions in sickle cell disease (SCD) and is classically induced by reactivation of previously formed antibodies. Improved antigenic matching has reduced alloimmunization and may reduce DHTR risk. We conducted a retrospective cohort study to investigate the incidence rate of DHTR in SCD patients receiving extended matched units (ABO/RhDCcEe/K/Fy^a /Jk^b /S). Occasional transfusion episodes (OTE) between 2011 and 2020 were reviewed for occurrence of DHTR symptoms using four screening criteria: decreased Hb, increased lactate dehydrogenase (LDH), pain, and dark urine. We included 205 patients who received a cumulative number of 580 transfusion episodes of 1866 RBC units. During follow-up, 10 DHTR events were observed. The incidence rate of DHTR was 13·8/1000 OTEs [95% confidence interval (CI): 7·37-22·2], with a cumulative incidence of 15·2% (95% CI: 8·4-24·0%) after 25 patients having received RBC units. One DHTR event was fatal (10%). Symptoms were misdiagnosed in four DHTR events (40%) as other acute SCD complications. Despite a lower incidence rate compared to most other studies, the incidence rate of DHTR in SCD remains high, in spite of extended matching of donor RBCs. Increased awareness of DHTR is of utmost importance to facilitate early diagnosis and, consequently, improve outcome.

Hyperhemolysis Syndrome Following Red Cell Exchange in a Newly Diagnosed Sickle Cell Disease Patient With Spinal Cord Infarction

Hyperhemolysis syndrome (HS) is a rare red blood cell (RBC) transfusion reaction that shares similarities with other hemolytic transfusion reactions. Because of this, it is important to recognize key presenting clinical and laboratory features in order to guide therapy. In this case report, a patient with a sickling hemoglobinopathy who developed HS is presented. The atypical nature of this case resides in the clinical presentation of paraplegia secondary to spinal cord infarction, increasingly complex blood group serological findings, and multiple RBC exchanges prior to the HS reaction. Once the patient was diagnosed with probable HS, approximately 4 weeks into her clinical course, RBC transfusion (including exchange transfusion) was withheld. Instead, corticosteroids and erythropoietin were initiated without complication. The patient remained stable with this treatment modality until her care was transferred to a hospital with a comprehensive sickle cell center. This case highlights the need to withhold transfusion in HS patients, barring exceptional circumstances, and the efficacy of initiating immunomodulatory and erythropoiesis stimulating therapies.

Increased Prevalence of Alloimmunization in Sickle Cell Disease? Should We Restore Blood Donation in French Guiana?

Patients with sickle cell disease often undergo frequent blood transfusions. This increases their exposure to red blood cell alloantigens of donor units, thus making it more likely that they produce alloantibodies. This cross-sectional study aimed to describe the prevalence of allo-immunization in patients with sickle cell disease who were monitored at Cayenne Hospital in 2016. Of the 451 patients recruited during the study period, 238 (52.8%) were female. There were 262 (58.1%) homozygous sickle cell and 151 (33.5%) compound heterozygous sickle cell patients. The median age of the participants was 23.09 years (range, 0.5–68). We noted different red blood cell extended phenotypes: -in the Duffy system, the Fy^a- Fy^b–profile was found in 299 patients (66%);—for the Kidd system, the most represented profile was Jka+ Jkb-, with 213 patients (47%). The Jka antigen was present in 355 patients;—in the MNS system, the S-s+ profile was found in 297 patients (66%);—the Lea antigen of the Lewis system was absent in 319 patients. The most frequent Rh phenotype in our patients was D+ C- E- c+ e+ K-, representing 51% of the patients. A total of 6,834 transfused packed red blood cell units were recorded. Sixty-eight patients (23%; 95% confidence interval, 20–25%) had detectable RBC alloantibodies. In multivariate logistic regression, only the mean number of single transfusions was statistically higher for the alloimmunized patients (p < 0.04). Thirteen (19%) of the patients with alloimmunization developed a delayed hemolytic transfusion reaction, thus representing 4.4% of the total number of transfused patients. Whether differences between donors from France vs. recipients from French Guiana could explain this high prevalence of alloimmunization to be examined. In conclusion, careful transfusion strategies for patients with RBC alloantibodies should allow further reduction of the rate of alloimmunization.

Screening for new red blood cell alloantibodies after transfusion in patients with sickle cell disease

BACKGROUND

Patients with sickle cell disease (SCD) are frequent recipients of red blood cell (RBC) transfusions and are at risk for RBC alloimmunization. RBC alloimmunization is diagnosed by identifying RBC alloantibodies as part of pre-transfusion testing, but this testing fails to detect alloantibodies that have evanesced. It may be beneficial to screen for new RBC alloantibody development after transfusion before possible antibody evanescence.

STUDY DESIGN AND METHODS

Our institution started a new initiative for episodically transfused patients with SCD to obtain at least one antibody screen 2-6 months after transfusion as part of their clinical care. A database was created to prospectively track all transfused patients for 1 year and their post-transfusion antibody screen results. Patients received prophylactically CEK-matched RBC units.

RESULTS

During the study year, 138 patients with SCD received a total of 242 RBC transfusions. Patients with a history of an RBC alloantibody (n = 13, 9.4%) had previously received more RBC units than non alloimmunized patients (median 11 vs. 2 RBC units, p = .0002). A total of 337 post-transfusion antibody screens were obtained in 127 patients (92.0%) with 110 patients (79.7%) having at least one antibody screen 2-6 months post-transfusion. With this prospective testing, two new RBC alloantibodies (anti-C and -M) were identified in two patients.

CONCLUSION

It is feasible to test for new RBC alloantibody development in most episodically transfused patients with SCD as part of their routine care. The yield of this screening appears low with CEK matching, but it could still provide important information for individual patients.

Antigen density dictates RBC clearance, but not antigen modulation, following incompatible RBC transfusion in mice

Incompatible red blood cell (RBC) transfusion can result in life-threatening transfusion complications that can be challenging to manage in patients with transfusion-dependent anemia. However, not all incompatible RBC transfusions result in significant RBC removal. One factor that may regulate the outcome of incompatible RBC transfusion is the density of the incompatible antigen. Despite the potential influence of target antigen levels during incompatible RBC transfusion, a model system capable of defining the role of antigen density in this process has not been developed. In this study, we describe a novel model system of incompatible transfusion using donor mice that express different levels of the KEL antigen and recipients with varying anti-KEL antibody concentrations. Transfusion of KEL+ RBCs that express high or moderate KEL antigen levels results in rapid antibody-mediated RBC clearance. In contrast, relatively little RBC clearance was observed following the transfusion of KEL RBCs that express low KEL antigen levels. Intriguingly, unlike RBC clearance, loss of the KEL antigen from the transfused RBCs occurred at a similar rate regardless of the KEL antigen density following an incompatible transfusion. In addition to antigen density, anti-KEL antibody levels also regulated RBC removal and KEL antigen loss, suggesting that antigen density and antibody levels dictate incompatible RBC transfusion outcomes. These results demonstrate that antibody-induced antigen loss and RBC clearance can occur at distinct antigen density thresholds, providing important insight into factors that may dictate the outcome of an incompatible RBC transfusion.

Delayed Severe Hemolytic Transfusion Reaction During Pregnancy in a Woman with β-Thalassemia Intermediate: Successful Outcome After Eculizumab Administration

BACKGROUND Delayed hemolytic transfusion reactions (DHTR) are life-threatening complications mostly triggered by red blood cell (RBC) transfusions in patients with hemoglobinopathy. CASE REPORT We present a case of DHTR and hyperhemolysis syndrome in a 39-year-old pregnant woman with a history of ß-thalassemia intermediate in whom the hemoglobin (Hb) level fell to 27 g/L after transfusion of 2 units of crossmatch-compatible packed RBCs. No allo- or auto-antibody formation was detected. Administration of intravenous immunoglobulins and methylprednisolone followed by anti-CD20 rituximab was tried, but was unsuccessful. Infusions of eculizumab (900 mg twice at a 7-day interval) followed by another course of intravenous immunoglobulins (2 g/kg/day for 5 days) and combined with repeated erythropoietin injections (darbepoetin alpha 300 µg/week) finally allowed biological and clinical improvement. Blood counts remained controlled until delivery. Despite signs of intrauterine growth retardation, she gave birth by cesarean section at 31 weeks of pregnancy to a 1.15-kg infant. CONCLUSIONS Eculizumab seems to be of benefit in DHTR associated with hyperhemolysis and should be used early in the treatment of this pathology. Despite premature birth, our case report showed an acceptable outcome for the infant when eculizumab treatment was used during pregnancy.

Recurrent Hyperhemolysis Syndrome in Sickle Cell Disease

Sickle cell disease is a disorder of hemoglobin. The abnormal hemoglobin S disrupts blood flow, thereby resulting in acute painful sickle cell crisis. These episodes frequently prompt packed red blood cell transfusions to replace a patient’s functional hemoglobin stores. Production of alloantibodies and autoantibodies to these transfusions can result in a rare, but serious, complication known as hyperhemolysis syndrome. Hyperhemolysis syndrome presents several challenges in regard to its acute management and the consequent difficulties in finding future compatible blood products. We report a case of recurrent hyperhemolysis syndrome. Both episodes occurred following orthopedic procedures, and the recurrent episode proved refractory to multiple treatments.

Hyperhemolysis Syndrome in a Patient with Sickle Cell Disease: A Case Report

Introduction

Hyperhemolysis syndrome (HHS) is a rare complication of repeat blood transfusions in sickle cell disease (SCD). This can occur acutely or have a delayed presentation and often goes unrecognized in the emergency department (ED) due to its rapid progression and similarity to acute chest syndrome and other common complications of SCD.

Case Report

We present a case of a 20-year-old male with SCD who presented to the ED with pain and tenderness in his lower extremities one day after discharge for a crisis. Unbeknownst to the ED team, during his admission he had received a blood transfusion. On presentation he was noted to have hyperkalemia, hyperbilirubinemia, anemia, and uncontrolled pain, and was admitted for sickle cell pain crisis. Over the next 36 hours, his hemoglobin dropped precipitously from 8.9 grams per deciliter (g/dL) to 4.2 g/dL (reference range: 11.5–14.5 g/dL), reticulocyte count from 11.7 % to 3.8% (0.4–2.2%), and platelets from 318,000 per cubic centimeter (K/cm³) to 65 K/cm³ (140–350 K/cm³). He also developed a fever, hypoxia, transaminitis, a deteriorating mental status, and severe lactic acidosis. Hematology was consulted and he was treated with methylprednisolone, intravenous immunoglobulin, two units of antigen-matched red blood cells, fresh frozen plasma, and cryoprecipitate. He was transferred to an outside hospital for exchange transfusion and remained hospitalized for 26 days with acute liver failure, bone marrow necrosis, and a fever of unknown origin.

Conclusion

Because of the untoward outcomes associated with delay in HHS diagnosis and the need for early initiation of steroids, it is important for emergency providers to screen patients with hemoglobinopathies for recent transfusion at ED presentation. Asking the simple question about when a patient’s last transfusion occurred can lead an emergency physician to include HHS in the differential and work-up of patients with sickle cell disease complications.

Delayed Hemolytic Transfusion Reaction in a Patient With Sickle Cell Disease and the Role of the Classical Complement Pathway: A Case Report

A 14-year-old female patient with sickle cell disease developed a severe delayed hemolytic transfusion reaction (DHTR) leading to multiple transfusions and intensive care management. To better understand the extent to which the classical complement pathway was contributing to her DHTR, we utilized the complement hemolysis using human erythrocytes (CHUHE) assay and the classical complement pathway inhibitor, PIC1. Residual discarded de-identified plasma and erythrocytes from the patient obtained from routine phlebotomy was acquired. These reagents were used in the CHUHE assay in the presence of increasing concentrations of PIC1. Complement-mediated hemolysis of the patient's erythrocytes occurred in her plasma and complement permissive buffer. Increasing concentrations of PIC1 dose-dependently inhibited hemolysis to levels found for the negative control - complement inhibitor buffer. Complement-mediated hemolysis was demonstrated by the CHUHE assay for this patient with sickle cell disease and severe DHTR. PIC1 inhibition of hemolysis suggested that the classical complement pathway was contributing to her DHTR.

Hyperhemolysis Syndrome in a Patient With Sickle Cell Disease and Acute Chest Syndrome

Sickle cell anemia patients often present to the hospital with acute vaso-occlusive pain crisis. Symptoms can include, but are not limited to, chest pain, abdominal pain, and musculoskeletal pain. These symptoms are brought about due to the pathology of the disease. Abnormal hemoglobin S causes red blood cells to band together, otherwise known as "sickling." These patients also often present with very low hemoglobin levels on initial evaluation. In most cases, packed red blood cell transfusions are needed in order to replenish these patient's functional hemoglobin supply. Unfortunately, transfusing sickle cell patients can lead to an unwanted consequence, that of hyperhemolysis syndrome, in which blood transfusions prompt further hemolysis of the already sickled red blood cells. When this complication arises, caution must be exercised in deciding the next steps of treatment.

Hyperhaemolytic Syndrome in Sickle Cell Disease: Clearing the Cobwebs

Sickle cell disease (SCD) presents with a dynamic background of haemolysis and deepening anaemia. This increases the demand for transfusion if any additional strain on haemopoiesis is encountered due to any other physiological or pathological causes. Patients with cerebrovascular accidents are placed on chronic blood transfusion; those with acute sequestration and acute chest syndrome are likewise managed with blood transfusion. These patients are prone to develop complications of blood transfusion including alloimmunization and hyperhaemolytic syndrome (HHS). This term is used to describe haemolysis of both transfused and "own" red cells occurring during or post-transfusion in sickle cell patients. Hyperhaemolysis results in worsening post-transfusion haemoglobin due attendant haemolysis of both transfused and autologous red cells. The mechanism underlying this rare and usually fatal complication of SCD has been thought to be secondary to changes in the red cell membrane with associated immunological reactions against exposed cell membrane phospholipids. The predisposition to HHS in sickle cell is also varied and the search for a prediction pattern or value has been evasive. This review discusses the pathogenesis, risk factors and treatment of HHS, elaborating on what is known of this rare condition.

Delayed Hemolytic Transfusion Reaction in a Sickle Cell Disease Patient: A Case Report

Alloimmunization has been reported in patients with sickle cell disease (SCD). Delayed hemolytic transfusion reaction (DHTR) is one of the complications of alloimmunization. DHTR is of particular clinical significance in this patient population as it may pose a diagnostic and management challenge to most healthcare providers. Symptoms of DHTR are often misinterpreted as pain crisis or worsening of baseline anemia. Furthermore, DHTR may take a turn for the worse in patients with SCD, thereby leading to worsening anemia and hyper-hemolytic crisis.

In this report, we discuss the case of a 33-year-old African female, with hemoglobin SS (Hb SS) SCD and a history of multiple blood transfusions in her home country of Nigeria, who presented to the emergency department with generalized body pain, which was typical of her prior vaso-occlusive crisis (VOC).

The trigger of her crisis was an acute onset of sepsis secondary to Escherichia coli (E. coli)-associated pyelonephritis. Owing to a worsening of her VOC and a significant drop in her steady-state Hb levels, she required a blood transfusion of one unit of packed red blood cells (PRBC), which was later complicated by a delayed hemolytic reaction and worsening anemia.

Delayed Hemolytic Transfusion Reaction in a Patient with Sickle Cell Disease: Case Report

Background

Blood transfusion is a key treatment of sickle cell disease (SCD) complications. Delayed hemolytic transfusion reaction (DHTR) is a delayed reaction, that occurs days to weeks following a transfusion, characterized by mild anemia and/or hyperbilirubinemia and is one of the serious complications of blood transfusion. The symptoms of DHTR resemble those of vaso-occlusive crisis secondary to SCD leading to difficulty or delaying in diagnosis of DHTR. DHTR may lead to multiple organ failure and death.

Case Report

A 31-year-old female patient with a known case of SCD presented to our ER in King Fahad hospital Hofuf in the Kingdom of Saudi Arabia, with a history of generalized body ache, exertional dyspnoea, headache and easy fatigability for a few days on a background history of episodic hospital admissions for SCD, but she was admitted 3 times over the previous 6 months and received 6 units of packed red blood cells (PRBCs). The last blood transfusion was 18 days earlier. She was sick and her Hb level was 4.5 g/dL with positive Coombs test and positive alloantibodies, diagnosed as DHTR. We treated her with prednisolone tablets 1 mg/kg daily, intravenous immunoglobulins, 0.4 gm/kg daily for 5 days, and rituximab 500 mg IV every week for 4 weeks. Her Hb level raised up to 8.2 g/dL and she was discharged in good condition.

Conclusion

Identifying risk factors for DHTR by history and presentation is urgently needed in order to risk stratify the transfusion regimen. It is important to avoid additional transfusions in these patients if possible because these may exacerbate the hemolysis and worsen the degree of anemia.

The cause and pathogenesis of hemolytic transfusion reactions in sickle-cell disease

PURPOSE OF REVIEW

The current review aims to summarize the epidemiology, cause, pathophysiology, and management of hemolytic transfusion reactions in sickle-cell disease (SCD).

RECENT FINDINGS

Patients undergoing occasional, isolated transfusions have been shown to have a higher risk of developing this condition. Despite the identification of well known risk factors, including alloimmunization, the pathophysiology of this syndrome remains unclear, as very severe forms with hyperhemolysis may develop in the absence of detectable antibodies, or with antibodies that are not considered to be clinically significant. Complement plays a crucial role in this reaction, particularly in cases of intravascular hemolysis. Complement triggers the reaction, but it also amplifies the inflammatory response and aggravates tissue damage. Free heme and hemoglobin are released and interact with complement, causing tissue damage.

SUMMARY

Hemolytic transfusion reactions are the most feared complications of blood transfusion in patients with SCD. This reaction is underdiagnosed because it mimics a vaso-occlusive crisis. Alloimmunization against red blood cell antigens is known to be a major trigger of this reaction, but abnormal complement activation and the underlying condition in patients with chronic hemolysis, may amplify the reaction. There is an urgent need to develop evidence-based approaches for preventing and treating this reaction.

Transfusion support: Considerations in pediatric populations

Over 400,000 units of blood and blood products are transfused to pediatric patients annually, yet only sparse high-quality data exist to guide the preparation and administration of blood products in this population. The direct application of data from studies in adult patients should be undertaken with caution, as there are dissimilarities in the pathology and physiology between adult and pediatric patients. We provide an overview of available evidence in the field of pediatric transfusion medicine, summarizing indications for blood product transfusion, thresholds for transfusion and indications for blood product modifications.

Catastrophic Delayed Hemolytic Transfusion Reaction in a Patient With Sickle Cell Disease Without Alloantibodies: Case Report and Review of Literature

While packed red blood cell (PRBC) transfusion therapy is a mainstay in the treatment of certain patients with sickle cell disease (SCD) and the standard of care for preoperative management, there are associated risks. Delayed hemolytic transfusion reaction (DHTR) is a risk of PRBC transfusion occurring 2 to 20 days from transfusion and typically presents with severe pain characteristic of vaso-occlusive crisis, fever, and hemolytic anemia. DHTRs are uncommon, occurring in only 4% to 11% of transfused patients with SCD, but may be catastrophic in nature with progression to multiorgan failure within hours. Here, we describe a case of a 20-year-old female with sickle cell SS disease who developed a severe DHTR 5 days following an elective preoperative PRBC transfusion, and rapidly progressed to multiorgan failure and death. This is the first reported case of a catastrophic DHTR in a patient with SCD without any detectable known or new alloantibodies.

Delayed haemolytic and serologic transfusion reactions: pathophysiology, treatment and prevention

PURPOSE OF REVIEW

The aim of this study was to summarize the basic epidemiology, pathophysiology and management of delayed serologic and delayed haemolytic transfusion reactions (DHTRs), as well as recent developments in our understanding of these adverse events.

RECENT FINDINGS

Several studies have identified risk factors for DHTRs, including high alloantibody evanescence rates among both general patient groups and those with sickle cell disease (SCD). Antibody detection is also hampered by the phenomenon of transfusion record fragmentation. There have also been enhancements in understanding of what may contribute to the more severe, hyperhaemolytic nature of DHTRs in SCD, including data regarding 'suicidal red blood cell death' and immune dysregulation amongst transfusion recipients with SCD. With growing recognition and study of hyperhaemolytic DHTRs, there have been improvements in management strategies for this entity, including a multitude of reports on using novel immunosuppressive agents for preventing or treating such reactions.

SUMMARY

Delayed serologic and haemolytic reactions remain important and highly relevant transfusion-associated adverse events. Future directions include further unravelling the basic mechanisms, which underlie DHTRs and developing evidence-based approaches for treating these reactions. Implementing practical preventive strategies is also a priority.

Adverse transfusion reactions in transfused children

Transfusion in paediatrics requires specific guidelines, because child physiology and pathology differ significantly as compared to adults. Adverse transfusion reactions in transfused children also vary in type and frequency, but there is a better understanding of these reactions in adults than in children. However, for the most frequent adverse transfusion reactions, the overall prevalence is higher in children than in adults, with the exception of post-transfusion red blood cell alloimmunisation, which is lower, excluding patients with haemoglobinopathies. In several studies, allergic reactions were the most frequently reported adverse transfusion reaction in paediatrics, and the platelet concentrate the most frequently implicated blood product. Early diagnosis of certain adverse transfusion reactions such as haemosiderosis, is essential in order to initiate the best therapy and obtain a good clinical outcome. The prevention of adverse transfusion reactions in children is required, but needs further clinical studies in paediatrics. Lastly, changes in technology, policy and clinical practices will improve transfusion safety in children.

A Differential Approach to an Uncommon Case of Acute Anemia in a Child With Sickle Cell Disease

Introduction: Hyperhemolytic crisis is a rare and dangerous complication of sickle cell disease where the hemoglobin level drops rapidly. This can quickly lead to organ failure and death. In the literature, most cases of hyperhemolysis in sickle cell patients followed a red cell transfusion. Case Summary: In this article, we report a case of a 6-year-old African American boy with sickle cell disease who presented with fever, increased work of breathing, and consolidation in the left lower lobe of the lung on chest X-ray. He initially improved with oxygen, fluids, and antibiotics but his hemoglobin acutely dropped from 7.6 to 6 g/dL the next day of admission. He was not previously transfused, and his reticulocyte count remained high. Subsequent transfusion recovered his hemoglobin. Conclusion: This case demonstrates that in the background of the chronic hemolysis of sickle cell disease, an acute anemia should warrant exploration of aplastic crisis (parvovirus infection), immune hemolytic anemia, hepatic sequestration crisis, splenic sequestration crisis, and hyperhemolytic crisis as possible etiologies. Ongoing reticulocytosis and a source of infection may direct suspicion especially toward hyperhemolytic crisis even without preceding red cell transfusion. We propose that the optimum management should include full supportive care (including transfusions if necessary) and treatment of the underlying cause of hemolysis (such as infections or drug exposure).

Alloimmunization in patients with sickle cell disease and underrecognition of accompanying delayed hemolytic transfusion reactions

BACKGROUND

Patients with sickle cell disease (SCD) often require red blood cell (RBC) transfusions but alloimmunization remains a significant complication. Alloantibodies can lead to delayed hemolytic transfusion reactions (DHTRs) days to weeks after a RBC transfusion, but may be underrecognized in patients with chronic hemolysis.

STUDY DESIGN AND METHODS

This retrospective study aimed to determine the incidence and severity of DHTRs associated with new antibody detection in a cohort of 624 patients with SCD who received transfusion with C-, E-, and K-matched RBCs from primarily African American donors over a 14-year period. We identified potential DHTRs by the change in hemoglobin (Hb) and %HbS at baseline, before transfusion, and up to 30 days after the transfusion that preceded new antibody identification.

RESULTS

Laboratory evidence of a DHTR was associated with 54 of 178 evaluable antibodies at first detection (30%), among which less than half were recognized by the patient or provider at the time of the event. A DHTR was associated with 26% of Rh antibodies identified in patients receiving serologic Rh-matched RBCs, and 38% of non-Rh antibodies. Twenty-one of the 54 DHTRs (39%) were associated with a Hb decline greater than 1 g/dL lower than pretransfusion values. Among these 21 severe DHTRs, Rh specificities were identified in 10 of 12 DHTRs in chronically transfused patients, while non-Rh specificities were associated with seven of nine DHTRs in episodically transfused patients.

CONCLUSION

High clinical suspicion and monitoring for DHTRs is warranted, as they may be more common in patients with SCD than previously appreciated.

Challenges in preventing and treating hemolytic complications associated with red blood cell transfusion

Red blood cell (RBC) transfusion support represents a critical component of sickle cell disease (SCD) management. However, as with any therapeutic intervention, RBC transfusion is not without risk. Repeat exposure to allogeneic RBCs can result in the development of RBC alloantibodies that can make it difficult to find compatible RBCs for future transfusions and can directly increase the risk of developing acute or delayed hemolytic transfusion reactions, which can be further complicated by hyperhemolysis. Several prophylactic and treatment strategies have been employed in an effort to reduce or prevent hemolytic transfusion reactions. However, conflicting data exist regarding the efficacy of many of these approaches. We will explore the challenges associated with predicting, preventing and treating different types of hemolytic transfusion reactions in patients with SCD in addition to describing future strategies that may aid in the management of the complex transfusion requirements of SCD patients.

Challenges in the treatment and prevention of delayed hemolytic transfusion reactions with hyperhemolysis in sickle cell disease patients

BACKGROUND

Delayed hemolytic transfusion reactions (DHTRs) are serious complications of RBC transfusion that can occur in previously alloimmunized patients. Patients who require episodic transfusions during heightened inflammatory states, such as patients with sickle cell disease (SCD), are particularly prone to alloimmunization and developing DHTRs with hyperhemolysis. While efforts to mitigate these hemolytic episodes via immunosuppressive drugs can be employed, the relative efficacy of various treatment options remains incompletely understood.

CASE REPORTS

In this study, we explored five patients with SCD and multiple RBC alloantibodies who received various forms of immunosuppressive therapy in an attempt to prevent or treat severe DHTRs.

RESULTS

The clinical course for these five patients provides insight into the difficulty of effectively treating and preventing DHTRs in patients with SCD with currently available immunosuppressive therapies.

CONCLUSION

Based on our experience, and the current literature, it is difficult to predict the potential impact of various immunosuppressive therapies when seeking to prevent or treat DHTRs. Future mechanistic studies are needed to identify the optimal treatment options for DHTRs in the presence or absence of distinct alloantibodies in patients with SCD.

Red blood cell alloimmunization and delayed hemolytic transfusion reactions in patients with sickle cell disease

Red blood cell (RBC) alloimmunization is more common in patients with sickle cell disease (SCD) than in any other studied patient population. The high prevalence of RBC alloimmunization is multi-factorial, likely involving the chronic hemolysis and inflammatory status of SCD itself, the transfusion burden of patients, and the RH genetic diversity of patients and blood donors, among other reasons. Antibody evanescence, or the decrease of RBC alloantibodies below levels detectable by blood bank testing, occurs frequently with fewer than 30% of alloantibodies estimated to be detected by current screening practices. Evanescence increases the likelihood that a patient with SCD will have a delayed hemolytic transfusion reaction upon future RBC exposure, with previously undetected alloantibodies coming roaring back in an anamnestic manner after exposure to the cognate RBC antigen. A subset of patients having delayed hemolytic transfusion reactions go on to experience hyperhemolysis; some but not all cases of hyperhemolysis are associated with previously evanescent RBC alloantibodies. There is an increasing appreciation of the association between RBC alloantibodies and RBC autoantibodies, as well as involvement of the alternative complement pathway in some instances of hyperhemolysis. A case report in this manuscript describes a highly alloimmunized patient with SCD who experiences a delayed hemolytic transfusion reaction with bystander hemolysis due to a previously evanescent, complement binding anti-M RBC alloantibody. Additional studies, including those involving multiple centers and countries, are needed to further understand RBC alloimmunization in patients with SCD and to develop strategies to prevent or mitigate potentially life-threatening hemolytic transfusion reactions.

Complement activation during intravascular hemolysis: Implication for sickle cell disease and hemolytic transfusion reactions

Intravascular hemolysis is a hallmark of a large spectrum of diseases, including the sickle cell disease (SCD), and is characterized by liberation of red blood cell (RBC) degradation products in the circulation. Released Hb, heme, RBC fragments and microvesicles (MVs) exert pro-inflammatory, pro-oxidative and cytotoxic effects and contribute to vascular and tissue damage. The innate immune complement system not only contributes to the RBC lysis, but it is also itself activated by heme, RBC MVs and the hypoxia-altered endothelium, amplifying thus the cell and tissue damage. This review focuses on the implication of the complement system in hemolysis and hemolysis-mediated injuries in SCD and in cases of delayed hemolytic transfusion reactions (DHTR). We summarize the evidences for presence of biomarkers of complement activation in patients with SCD and the mechanisms of complement activation in DHTR. We discuss the role of antibodies-dependent activation of the classical complement pathway as well as the heme-dependent activation of the alternative pathway. Finally, we describe the available evidences for the efficacy of therapeutic blockade of complement in cases of DHTR. In conclusion, complement blockade is holding promises but future prospective studies are required to introduce Eculizumab or another upcoming complement therapeutic for DHTR and even in SCD.

Anti-N and anti-Doa immunoglobulin G alloantibody-mediated delayed hemolytic transfusion reaction with hyperhemolysis in sickle cell disease treated with eculizumab and HBOC-201: case report and review of the literature

BACKGROUND

Delayed hemolytic transfusion reaction (DHTR) with hyperhemolysis is a potentially fatal complication resulting from alloimmunization that can cause severe hemolysis of both transfused and intrinsic red blood cells (RBCs). Patients with sickle cell disease often receive multiple RBC units during their lifetime and thus are likely to develop alloantibodies that increase the risk for DHTR. Treatment to decrease hemolysis includes intravenous immunoglobulin (IVIG), steroids, eculizumab, rituximab, and plasmapheresis in addition to erythropoietin (EPO), intravenous (IV) iron, vitamin B12, and folate to support erythropoiesis. RBC transfusion is preferably avoided in DHTR due to an increased risk of exacerbating the hemolysis.

CASE REPORT

We report a rare case of anti-N and anti-Do^a immunoglobulin (Ig)G alloantibody-mediated life-threatening DHTR with hyperhemolysis in a patient with hemoglobin SS after RBC transfusion for acute chest syndrome who was successfully treated with eculizumab and HBOC-201 (Hemopure) in addition to steroids, IVIG, EPO, IV iron, and vitamin B12. HBOC-201 (Hemopure) was successfully used as a RBC alternative in this patient.

CONCLUSION

Anti-N and anti-Do^a IgG alloantibodies can rarely cause severe life-threatening DHTR with hyperhemolysis. HBOC-201 (Hemopure) can be a lifesaving alternative in this scenario. Our report also supports the use of eculizumab in DHTR; however, prospective studies are needed to determine the appropriate dose and sequence of eculizumab administration.

Complement Component 3 Negatively Regulates Antibody Response by Modulation of Red Blood Cell Antigen

Red blood cell (RBC) alloimmunization can make it difficult to procure compatible RBCs for future transfusion, directly leading to increased morbidity and mortality in transfusion-dependent patients. However, the factors that regulate RBC alloimmunization remain incompletely understood. As complement has been shown to serve as a key adjuvant in the development of antibody (Ab) responses against microbes, we examined the impact of complement on RBC alloimmunization. In contrast to the impact of complement component 3 (C3) in the development of an immune response following microbial exposure, transfusion of C3 knockout (C3 KO) recipients with RBCs expressing KEL (KEL RBCs) actually resulted in an enhanced anti-KEL Ab response. The impact of C3 appeared to be specific to KEL, as transfusion of RBCs bearing another model antigen, the chimeric HOD antigen (hen egg lysozyme, ovalbumin and Duffy), into C3 KO recipients failed to result in a similar increase in Ab formation. KEL RBCs experienced enhanced C3 deposition and loss of detectable target antigen over time when compared to HOD RBCs, suggesting that C3 may inhibit Ab formation by impacting the accessibility of the target KEL antigen. Loss of detectable KEL on the RBC surface did not reflect antigen masking by C3, but instead appeared to result from actual removal of the KEL antigen, as western blot analysis demonstrated complete loss of detectable KEL protein. Consistent with this, exposure of wild-type B6 or C3 KO recipients to KEL RBCs with reduced levels of detectable KEL antigen resulted in a significantly reduced anti-KEL Ab response. These results suggest that C3 possesses a unique ability to actually suppress Ab formation following transfusion by reducing the availability of the target antigen on the RBC surface.

Red cell transfusion in paediatric patients with thalassaemia and sickle cell disease: Current status, challenges and perspectives

Notwithstanding the high safety level of the currently available blood for transfusion and the decreasing frequency of transfusion-related complications, administration of labile blood products to paediatric patients still poses unique challenges and considerations. The incidence of thalassaemia and sickle cell disease in the paediatric population may be high enough under specific racial and geographical contexts. Red cell transfusion is the cornerstone of β-thalassaemia treatment and one of the most effective ways to prevent or correct specific acute and chronic complications of sickle cell disease. However, this life-saving strategy comes with its own complications, such as additional iron overload, alloimmunization and haemolytic reactions, among others. In paediatrics, the dependency of the transfusion outcome upon disease and other recipient characteristics is more prominent compared with the adults, owing to differences in developmental maturity and physiology that render them more susceptible to common risks, exacerbate the host response to transfused cells, and modify the type or the clinical severity of the transfusion-related morbidity. The adverse branch of red cell transfusion is likely the overall effect of several factors acting synergistically to shape the clinical phenotype of this therapy, including inherent donor/blood unit variables, like antigenicity, red cell deformability and extracellular vesicles, as well as recipient variables, such as history of alloimmunization and inflammation level at time of transfusion. This review focuses on paediatric patients with β-thalassaemia and sickle cell disease as a recipient group with distinct transfusion-related characteristics, and introduces new concepts for consideration, not adequately studied and elucidated so far.

How I safely transfuse patients with sickle-cell disease and manage delayed hemolytic transfusion reactions

Transfusions can be a life-saving treatment of patients with sickle-cell disease (SCD). However, availability of matched units can be limiting because of distinctive blood group polymorphisms in patients of African descent. Development of antibodies against the transfused red blood cells (RBCs), resulting in delayed hemolytic transfusion reactions (DHTRs), can be life-threatening and pose unique challenges for this population with regard to treatment strategies and transfusion management protocols. In cases where the transfused cells and the patient's own RBCs are destroyed, diagnosis of DHTR can be difficult because symptoms may mimic vaso-occlusive crisis, and frequently, antibodies are undetectable. Guidelines are needed for early diagnosis of DHTR because treatment may need to include temporarily withholding any new transfusions to avoid further hemolysis. Also needed are case-control studies to optimally tailor treatments based on the severity of DHTR and develop preventive transfusion strategies for patients at DHTR risk. Here, we will review gaps in knowledge and describe through case studies our recommended approach to prevent alloimmunization and to diagnose and treat symptomatic DHTRs for which complementary mechanistic studies to understand their pathogenesis are sorely needed.

When a transfusion in an emergency service is not really urgent: hyperhaemolysis syndrome in a child with sickle cell disease

A 13-month-old boy with sickle cell disease (SCD) from Equatorial Guinea, who had recently arrived in Spain, presented with fever. He had suffered from malaria and had received a blood transfusion. Following physical examination and complementary tests, intravenous antibiotics and a red blood cell (RBC) transfusion were administered. Soon after a second transfusion 5 days later, the haemoglobin level fell below pretransfusion levels, together with reticulocytopenia, and haematuria-the so-called hyperhaemolysis syndrome-requiring intensive care and treatment with intravenous immunoglobulins and corticosteroids, with resolution of the complication. We want to emphasise the importance of suspecting this rare, though severe complication that can appear after any RBC transfusion especially in patients with SCD, as the clinical syndrome can simulate other more common complications of these patients and a further transfusion is contraindicated. There is no standardised treatment, but intravenous immunoglobulin and corticosteroids are usually effective.

Whole-exome sequencing of sickle cell disease patients with hyperhemolysis syndrome suggests a role for rare variation in disease predisposition

BACKGROUND

Hyperhemolysis syndrome (HHS) is an uncommon, but life-threatening, transfusion-related complication of red blood cell transfusion. HHS has predominantly been described in patients with sickle cell disease (SCD) and is difficult to diagnose and treat. The pathogenesis of HHS, including its occurrence in only a subset of apparently susceptible individuals, is poorly understood. We undertook whole-exome sequencing (WES) of 12 SCD-HHS patients to identify shared genetic variants that might be relevant to the development of HHS.

STUDY DESIGN AND METHODS

DNA from adults with SCD having at least one previous episode of HHS were subject to WES. High-quality variants were passed through a series of bioinformatics filters to identify variants that were uncommon among African populations represented in public databases. Recurrent, putative loss-of-function variants occurring in biologically plausible genes were prioritized and then genotyped in a larger, ancestry-matched cohort of non-HHS controls.

RESULTS

A rare, heterozygous stop-gain variant (p.Glu210Ter) in MBL2 was significantly enriched among HHS cases (p = 0.002). This variant is predicted to result in a premature termination codon that escapes nonsense-mediated mRNA decay, potentially leading to a novel phenotype. We also observed a complex insertion-deletion variant in the final exon of KLRC3 that was enriched among cases (p = 0.0019), although neither variant was found among seven pediatric SCD-HHS patients.

CONCLUSION

Our results suggest a potential role for rare genetic defects in the development of HHS among adult SCD patients. Such enriched variants may ultimately be useful for identifying high-risk individuals and informing therapeutic approaches in HHS.

Incidence and predictive score for delayed hemolytic transfusion reaction in adult patients with sickle cell disease

Delayed hemolytic transfusion reaction (DHTR) is a life-threatening complication of transfusion in sickle cell disease (SCD). The frequency of DHTR is underestimated because its symptoms mimic those of vaso-occlusive crisis and antibodies (Abs) are often not detectable. No predictive factors for identifying patients likely to develop DHTR have yet been defined. We conducted a prospective single-center observational study over 30 months in adult sickle cell patients. We included 694 transfusion episodes (TEs) in 311 patients, divided into occasional TEs (OTEs: 360) and chronic transfusion program (CTEs: 334). During follow-up, 15 cases of DHTR were recorded, exclusively after OTEs. DHTR incidence was 4.2% per OTE (95% CI [2.6; 6.9]) and 6.8% per patient during the 30 months of the study (95% CI [4.2; 11.3]). We studied 11 additional DHTR cases, to construct a predictive score for DHTR. The DHTR mortality is high, 3 (11.5%) of the 26 DHTR patients died. The variables retained in the multivariate model were history of DHTR, number of units previously transfused and immunization status before transfusion. The resulting DHTR-predictive score had an area under the ROC curve of 0.850 [95% CI: 0.780-0.930], a negative-predictive value of 98.4% and a positive-predictive value of 50%. We report in our study population, for the first time, the incidence of DHTR, and, its occurrence exclusively in occasionally transfused patients. We also describe a simple score for predicting DHTR in patients undergoing occasional transfusion, to facilitate the management of blood transfusion in SCD patients.

Fatal delayed haemolytic transfusion reaction in a patient without previous transfusions but with an obstetric history of 13 pregnancies

Delayed haemolytic transfusion reaction is a rare, life-threatening complication of blood transfusion that has been typically described among patients with sickle cell disease (SCD) due to alloimmunisation induced by their exposure to red blood cell antigens through recurrent transfusions. We report the case of a patient who suffered from fatal delayed haemolytic transfusion reaction (DHTR) occurring 1 week after blood transfusion. Indirect antiglobulin testing confirmed the presence of anti-Kell antibodies that were absent in the pretransfusion sample. The patient did not receive blood transfusions in the past, but her obstetric history was remarkable for 13 pregnancies. Although DHTR occurs more commonly among patients with SCD, this type of reaction can occur in any patient who is able to mount an immune response. We would to like to draw the attention of physicians to this rare and potentially lethal complication of blood transfusion, especially in grand multiparous women.