Delayed hemolytic transfusion reaction due to anti-Go(a), an antibody against the low-prevalence Gonzales antigen

Modeling primitive and definitive erythropoiesis with induced pluripotent stem cells

ABSTRACT

During development, erythroid cells are produced through at least 2 distinct hematopoietic waves (primitive and definitive), generating erythroblasts with different functional characteristics. Human induced pluripotent stem cells (iPSCs) can be used as a model platform to study the development of red blood cells (RBCs) with many of the differentiation protocols after the primitive wave of hematopoiesis. Recent advances have established that definitive hematopoietic progenitors can be generated from iPSCs, creating a unique situation for comparing primitive and definitive erythrocytes derived from cell sources of identical genetic background. We generated iPSCs from healthy fetal liver (FL) cells and produced isogenic primitive or definitive RBCs which were compared directly to the FL-derived RBCs. Functional assays confirmed differences between the 2 programs, with primitive RBCs showing a reduced proliferation potential, larger cell size, lack of Duffy RBC antigen expression, and higher expression of embryonic globins. Transcriptome profiling by scRNA-seq demonstrated high similarity between FL- and iPSC-derived definitive RBCs along with very different gene expression and regulatory network patterns for primitive RBCs. In addition, iPSC lines harboring a known pathogenic mutation in the erythroid master regulator KLF1 demonstrated phenotypic changes specific to definitive RBCs. Our studies provide new insights into differences between primitive and definitive erythropoiesis and highlight the importance of ontology when using iPSCs to model genetic hematologic diseases. Beyond disease modeling, the similarity between FL- and iPSC-derived definitive RBCs expands potential applications of definitive RBCs for diagnostic and transfusion products.

Hemolytic Disease of the Fetus and Newborn Due to Anti-Gonzales Antibody

Hemolytic disease of the fetus and newborn (HDFN) is an immune-mediated condition caused by the production of maternal antibodies to fetal red blood cells. This condition most commonly arises due to Rh factor incompatibility. The case presented here displays an example of HDFN in which the mother and fetus's blood type was O+. Upon further investigation, it was determined that the mother is a producer of anti-Gonzales antibodies (anti-Go(a)). With no cases published in the 21st century, this antibody is a rare cause of HDFN. Anti-Go(a) is produced against the Go antigen, a low-frequency Rh antigen found predominantly in African and Puerto Rican populations. Bringing awareness to this rare cause of HDFN may accelerate diagnosis when the physician is faced with non-ABO and non-Rh isoimmunization in these ethnic groups.

The use of pluripotent stem cells to generate diagnostic tools for transfusion medicine

Red blood cell (RBC) transfusion is one of the most common medical treatments, with more than 10 million units transfused per year in the United States alone. Alloimmunization to foreign Rh proteins (RhD and RhCE) on donor RBCs remains a challenge for transfusion effectiveness and safety. Alloantibody production disproportionately affects patients with sickle cell disease who frequently receive blood transfusions and exhibit high genetic diversity in the Rh blood group system. With hundreds of RH variants now known, precise identification of Rh antibody targets is hampered by the lack of appropriate reagent RBCs with uncommon Rh antigen phenotypes. Using a combination of human-induced pluripotent stem cell (iPSC) reprogramming and gene editing, we designed a renewable source of cells with unique Rh profiles to facilitate the identification of complex Rh antibodies. We engineered a very rare Rh null iPSC line lacking both RHD and RHCE. By targeting the AAVS1 safe harbor locus in this Rh null background, any combination of RHD or RHCE complementary DNAs could be reintroduced to generate RBCs that express specific Rh antigens such as RhD alone (designated D--), Goa+, or DAK+. The RBCs derived from these iPSCs (iRBCs) are compatible with standard laboratory assays used worldwide and can determine the precise specificity of Rh antibodies in patient plasma. Rh-engineered iRBCs can provide a readily accessible diagnostic tool and guide future efforts to produce an alternative source of rare RBCs for alloimmunized patients.

Red Blood Cell Alloimmunization in Transfused Patients With Sickle Cell Disease in Sub-Saharan Africa; a Systematic Review and Meta-Analysis

Sickle cell disease (SCD) is the most common monogenic disorder in sub-Saharan Africa (SSA). Blood transfusion to increase the oxygen carrying capacity of blood is vital in the management of many patients with SCD. However, red blood cell (RBC) alloimmunization is a major challenge to transfusions in these patients. Commonly in SSA, pretransfusion tests only involve ABO D grouping and compatibility without RBC antibody testing. Data on the frequency of RBC alloimmunization in patients with SCD in SSA are limited. We performed a systematic review and meta-analysis on available data on alloimmunization in transfused patients with SCD to determine the published prevalence of RBC alloimmunization in SCD patients in SSA. Six databases were systematically searched to identify relevant studies, without year or language restrictions. In all, 249 articles were identified and 15 met our selection criteria. The overall proportion of alloimmunization was 7.4 (95% confidence interval: 5.1-10.0) per 100 transfused patients. Antibodies against E, D, C, and K antigens accounted for almost half of antibody specificities, and antibodies to low- and high-frequency antigens were also common and represented almost 30% (20% to low-frequency antigens and 9% to high-frequency antigens) of specificities. Heterogeneity between studies was moderate, and meta-analysis found region of Africa as the major contributor to the heterogeneity. We also observed inconsistencies across studies in reporting of factors that may influence alloimmunization. This review provides an overview of the extent of the alloimmunization problem in SSA and provides a baseline against which to compare the effect of any interventions to reduce the alloimmunization risk.

How we evaluate red blood cell compatibility and transfusion support for patients with sickle cell disease undergoing hematopoietic progenitor cell transplantation

Multiple hematopoietic progenitor cell (HPC) transplantation options for patients with sickle cell disease (SCD) are currently under investigation. Patients with SCD have a high rate of alloimmunization to red blood cell antigens, often complicating transfusion support. Transfusion reactions, including acute and delayed hemolytic reactions, have been observed despite immunosuppressive regimens. Allogeneic donor transplants have been shown to carry a risk of prolonged reticulocytopenia and acute hemolysis with severe anemia in nonmyeloablative regimens. We discuss our experience providing transfusion support to patients with SCD undergoing HPC transplantation, propose an outline for a complete pretransplantation evaluation, and discuss donor/recipient compatibility issues and their implications.

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.

High immunogenicity of red blood cell antigens restricted to the population of African descent in a cohort of sickle cell disease patients

BACKGROUND

Sickle cell disease (SCD) patients undergo multiple red blood cell (RBC) transfusions and are regularly exposed to low-prevalence (LP) antigens specific to individuals of African descent. This study evaluated the prevalence of antibodies against LP antigens in SCD patients and the need to identify these antibodies in everyday practice.

STUDY DESIGN AND METHODS

Plasma from 211 SCD patients was tested with RBCs expressing the following LP antigens: RH10 (V), RH20 (VS), RH23 (D^W ), RH30 (Go^a ), KEL6 (Js^a ), and MNS6 (He).

RESULTS

Nine LP antibodies were found in eight patients (3.8%): five anti-RH23, two anti-RH30, and two anti-MNS6. The exposure risk, calculated for each LP antigen, was below 3% per RBC unit, for all antigens tested. Thus, in this cohort of transfused SCD patients, the prevalence of LP antibodies was similar to that of antibodies against antigens of the FY, JK, and MNS blood group systems. These findings also reveal the occurrence of anti-RH23 in SCD patients. No anti-RH20 or anti-KEL6 were found, despite the high frequency of mismatch situations.

CONCLUSION

These results highlight the immunogenicity of these LP antigens, and the evanescence of antibodies against LP antigens. They also highlight the importance of appropriate pretransfusion testing for patients frequently transfused, who are likely to be exposed to multiple types of blood group antigens.

Red blood cell alloimmunization in sickle cell disease: pathophysiology, risk factors, and transfusion management

Red blood cell transfusions have reduced morbidity and mortality for patients with sickle cell disease. Transfusions can lead to erythrocyte alloimmunization, however, with serious complications for the patient including life-threatening delayed hemolytic transfusion reactions and difficulty in finding compatible units, which can cause transfusion delays. In this review, we discuss the risk factors associated with alloimmunization with emphasis on possible mechanisms that can trigger delayed hemolytic transfusion reactions in sickle cell disease, and we describe the challenges in transfusion management of these patients, including opportunities and emerging approaches for minimizing this life-threatening complication.

Relevance of RH variants in transfusion of sickle cell patients

Transfusion remains the main treatment of sickle cell disease patients. Red cell alloimmunization is frequent because of the antigen disparities between patients of African descent and donors of European ancestry. Alloimmunization is associated with severe hemolytic transfusion reaction, autoantibody formation, and difficulties in the management of transfusion compatibility. Beside common antigens, a number of different RH variant antigens found in individuals of African descent can be involved in alloimmunization. If some variants, such as Hr(S) negative antigens, are known to prone significant alloantibodies and delayed hemolytic transfusion reactions, it is not clear whether all the described variants represent a clinical risk for sickle cell disease patients. The knowledge of the clinical relevance of RH variants is a real issue. An abundance of molecular tools are developed to detect variants, but they do not distinguish those likely to prone immunization from those that are unlikely to prone immunization and delayed hemolytic transfusion reactions. A strategy of prevention, which generally requires rare red blood cells, cannot be implemented without this fundamental information. In this review, we discuss the relevance of RH variants in sickle cell disease, based on the published data and on our experience in transfusion of these patients.

[Study of 206 transfused sickle cell disease patients: immunization, transfusion safety and red blood cell supply]

BACKGROUND

Prevention of hemolytic transfusion reactions depends upon our capacity to prevent allo-immunization and conflicts between antigens of transfused red blood cells and antibodies produced by the recipient. In this study, we show that to secure transfusion of sickle cell disease patients, it is necessary to take into account their immunohematologic characteristics in the organization of transfusion.

METHODS AND RESULTS

Immunohematological data of 206 chronically transfused patients have been collected as well as phenotypes of transfused units. In order to prevent allo-immunization against C and E antigens for patients typed D+C-E-c+e+ (56%), 26% of the transfused units were D-C-E-c+e+. We found that 47% of the patients had a history of allo-immunization, whereas only 15% produced an antibody the day of inclusion in the study. The non-detectable antibodies were frequently known as dangerous for transfusion. Finally, this study shows the frequency of anti-D in D+ patients and anti-C in C+ patients, pointing out the question of partial antigens.

CONCLUSION

To insure optimal transfusion safety for sickle cell disease patients, three points have to be improved: blood donation within the Afro-Caribbean community living in France, access to history of immuno-hematological data, detection of variant antigens, especially within the RH blood system.

Current issues with blood transfusions in sickle cell disease

With increased recognition of the profound morbidity of sickle cell disease and with growing evidence of the efficacy of transfusion therapy in prevention and treatment of sickle cell complications, most patients now receive intermittent transfusion therapy. The purpose of this report is to review blood component therapy and Its risks for sickle cell patients. Packed red cells are the preferred blood component. Leukocyte-reduced units should be standard because of their beneficial effects in reducing alloimmunization, transfusion reactions, platelet refractoriness, and infection transmission. The use of washed, frozen, or Irradiated units is limited to specific problems. Sickle trait-positive units function normally, but because of difficulties with calculating hemoglobin S percentages and leukocyte filters, they are not routinely used. Transfusion-acquired infections have shown a marked decrease but still present a major risk. Viral hepatitis transmission is currently low, but at least 10% of adult sickle cell patients are hepatitis C positive, and they often have liver damage. Although bacterial infections are rare, they account for 16% of transfusion-related fatalities. Patients who are iron overloaded are particularly vulnerable to Yersina enterocolitica. Red cell alloimmunization is a serious problem that could potentially affect 50% of transfused patients. However, preventive phenotypic matching for common antigens can minimize alloimmunization; limited matching for at least E, C, and K has become the standard of care. Recently, more patients are being identified who have developed red cell autoantibodies, which can mask alloantibodies and occasionally are hemolytic. Careful laboratory evaluation of all cases is essential. Transfusions also may trigger sickle cell events, including pain crises, stroke, and acute pulmonary deterioration. In part, these are induced by blood viscosity and increased blood pressure. Diuretic therapy and close monitoring of transfusion volume and vital signs can minimize these events. In summary, transfusion therapy carries risks, but the routine use of leukocyte-reduced, phenotypically matched units in conjunction with close monitoring of patients can make transfusion therapy safer.