Coexistence of autoantibodies and alloantibodies to red blood cells due to blood transfusion

Immunohematological evaluation of red cell alloimmunization and statistical assessment of various adsorption techniques in warm autoimmune hemolytic anemia

Adsorption techniques are widely applied to detect underlying masked alloantibodies in warm autoimmune hemolytic anemia (WAIHA). We established various adsorption techniques with an aim to detect alloimmunization in WAIHA This study conducted over a period of nine years included 298 patients of WAIHA. Complete immunohematological evaluation was performed on these 298 samples following departmental protocols. Clinical and laboratory details of patients were obtained from patient files. Various adsorption methods were performed and statistically evaluated in the study. Out of 479 cases of autoimmune hemolytic anemia, WAIHA comprised of 62.2 % (N = 298). A total of 139 (46.6 %) serum samples revealed autoantibodies. Adsorption study was performed in 101 (72.7 %) indicated samples and 24 (23.8 %) of these showed 26 alloantibodies. Among the patients subjected to adsorption study hemolytic marker were significantly deranged in the alloimmunization group (p < 0.01). Polyethylene glycol (PEG) adsorption was the quickest (52.2-54.6 min) of all adsorption techniques with minimum (1.3-1.5) numbers of adsorptions needing for complete removal of serum antibodies. The LISS-papain (LP) technique was found to be more sensitive and specific compared to the other two techniques. The agreement between PEG adsorption and LP adsorption was found to be 'perfect' (96.4 %) with a Cohen's kappa (k) value of 0.9. We conclude that identification of alloantibody specificities underlying a warm autoantibody is critical for a safe and effective transfusion. All WAIHA patients with history of blood transfusion, pregnancy or both should be subjected to adsorption study. Selection of a suitable adsorption technique depends on multiple important factors.

Implementation of a molecular genotyping protocol for patients with warm autoantibodies

BACKGROUND

Warm autoantibodies (WAAs) cause delays and additional expenses while determining suitable products when using a traditional protocol (TP). In 2013, Carter BloodCare Immunohematology Reference Laboratory (IRL) introduced a molecular protocol (MP) for patients with WAAs.

STUDY DESIGN AND METHODS

Retrospective review of records for samples referred to the IRL from November 2004 to September 2020, was performed. Referrals, alloantibody(ies), gender, and age were recorded. Additionally, the count of common clinically significant antigens needed for phenotypically matched red blood cells (RBCs) were recorded for patients in MP. To further analyze charges and time spent testing patients with WAAs, 300 patients were selected.

RESULTS

Analysis of average charges to the referring hospital and time spent testing in the IRL determined savings at two or more referrals. Overall, 219 of 300 (73%) of patients in the study met or exceeded the number of referrals. Further analysis shows that while the population of patients with WAA (n = 300) shared similar demographics, there was a statistically significant difference between the average time testing patients in TP (M = 264.18, SD = 15.06) and MP (M = 156.00, SD = 90.37), t(157) = 14.46, p < .001, 95% confidence interval [CI] (93.41-122.97). Additionally, the assumption that each patient received two RBCs per referral provided no statistically significant difference between average charges to the hospitals of patients in TP (M = 1222.58, SD = 165.69) and MP (M = 1269.78, SD = 433.52), t(192) = -1.25, p = .214, 95% CI (-121.95-27.54).

CONCLUSION

The MP has been effective in saving time spent testing patients with WAAs, which benefits referring hospitals, patients, and IRLs. Charges for prophylactic phenotypically matched blood were negligible and a MP would alleviate some of the current laboratory difficulties while providing safe products to patients.

Cellular Nanosponges for Biological Neutralization

Biological neutralization represents a general strategy that deploys therapeutic agents to bind with harmful molecules or infectious pathogens, block their bioactivity, and thus prevent them from causing the diseases. Here, a comprehensive review of using cell-membrane-coated nanoparticles, namely "cellular nanosponges," as host decoys for a wide range of biological neutralization applications is provided. Compared to traditional neutralization strategies, the cellular nanosponges stand out by mimicking susceptible host cells rather than accommodating the structures of the causative agents for the design of therapeutics. As all pathological agents must interact with host cells for bioactivity, nanosponges bypass the diversity of these agents and create function-driven and broad-spectrum neutralization solutions. The review focuses on the recent progress of using this new nanomedicine platform for neutralization against five primary pathological agents, including bacterial toxins, chemical toxicants, inflammatory cytokines, pathological antibodies, and viruses. Existing studies have established cellular nanosponges as versatile tools for biological neutralization. A thorough review of the cellular nanosponge technology is expected to inspire more refined cellular nanosponge designs and unique neutralization applications to address unsolved medical problems.

Antikörper-Adsorptionsmethoden für die Diagnostik von erythrozytären Alloantikörpern bei Patienten mit panreaktiven Autoantikörpern

Der Nachweis und die Differenzierung von erythrozytären Alloantikörpern bei Patienten mit freien wärmereaktiven Autoantikörpern (WAK) im Plasma stellt das immunhämatologische Labor vor eine Herausforderung. Eine Allo- und/oder Autoadsorption kann die Autoantikörperreaktivität des Patientenplasmas reduzieren oder vollständig entfernen und vorhandene Alloantikörper demaskieren. Wir schlagen einen diagnostischen Stufenplan vor, der diese Methoden besonders berücksichtigt, und eine Transfusionsstrategie, die sich an der Dringlichkeit der Transfusion orientiert. Eine indizierte Transfusion darf durch die Diagnostik nicht verzögert werden.

Frequency and specificity of Red blood cell alloantibodies in multitransfused Egyptian patients with hematological and nonhematological malignancies

BACKGROUND

Repeated blood transfusions can result in the production of alloantibodies against one or more red blood cell (RBC) antigens, which can complicate future transfusions.

AIM

This study aims to determine the frequency and specificities of RBC alloantibodies in multitransfused adult cancer patients admitted at the National Cancer Institute, Cairo University.

METHODS

This cohort study enrolled 2000 multitransfused cancer patients diagnosed with different types of malignancies; they were screened for RBC alloantibodies using Serascan Diana 3 and Identisera Diana 11-cell identification panels (Diagnostic Grifols, Spain).

RESULTS

Of the 2000 patients tested, 25 had autoantibodies and were excluded from the study. Of the remaining 1975 patients, 181 patients had a total of 267 different alloantibodies (9.16%), with some having more than 1 antibody detected. Our study showed that more female patients (63%) than male patients (37%) had acquired RBC alloantibodies, and a higher prevalence of alloantibodies in patients with nonhematological malignancies (14%) compared with those with hematological malignancies (6.5%). The highest percentage of alloantibodies belongs to the Rh blood group system, followed by the Kell system, then Duffy, MNS, Kidd, and Lewis. Patients who received combined chemotherapy and immunotherapy exhibited a lesser antibody response compared to other patients.

CONCLUSION

The prevalence of alloimmunization in our study is comparable to previous reports on oncology patients. Repeated blood transfusions, which can lead to alloimmunization, often complicate future transfusions. Therefore, we recommend extending phenotype matching for patients who are presumed to depend on blood transfusions in the long term.

Prevalence of red-blood-cell and non-red-blood-cell-targeted autoantibodies in alloimmunized postpartum women

BACKGROUND AND OBJECTIVES

Alloantibodies against red-blood-cell (RBC) antigens often coincide with alloantibodies against leucocytes and platelets and sometimes with autoantibodies towards various antigens. Chimerism may be one of the factors responsible for the combination of allo- and autoantibodies. Women with alloantibodies against RBC antigens causing haemolytic disease of the fetus and neonate may need to receive intrauterine transfusions. These transfusions increase not only maternal antibody formation but also fetomaternal bleeding and may enhance fetal chimerism. We determined the prevalence of and risk factors for autoantibodies against some common clinical target antigens, in alloimmunized women after IUT.

MATERIALS AND METHODS

We tested for autoantibodies against RBC, anti-thyroid peroxidase, anti-extractable nuclear antigens, anti-cyclic citrullinated proteins and anti-tissue transglutaminase. Women with and without autoantibodies were compared for age; number of RBC alloantibodies, pregnancies and IUTs, and other factors that may play a role in immunization.

RESULTS

Non-RBC-targeted autoantibodies were present in 40 of 258 tested women (15·5%, with 90% anti-TPO specificity), comparable to the prevalence reported in healthy Dutch women of these ages. Surprisingly, compared with women who had a single RBC alloantibody, a significantly higher proportion of women with multiple RBC alloantibodies had autoantibodies (5·3% and 18·4%, respectively; odds ratio 4·06, 95% CI: 1·20-13·7). Other characteristics of women with and without autoantibodies were not different.

CONCLUSION

Multiple RBC alloantibodies after extensive allogeneic exposure during pregnancy and presumed increased fetomaternal chimerism are not associated with (selected) autoantibodies. Lack of allo-RBC multi-responsiveness seems associated with decreased auto(-TPO) antibody formation.

Comparison of two column agglutination tests for red blood cell antibody testing

Background

Several sensitive methods are available for red blood cell (RBC) antibody screening. Among these, gel and glass card systems have demonstrated comparably good performance in retrospective studies and are widely used in routine patient diagnostics, but their performance in prospective studies has not been sufficiently characterised.

Patients and methods

Gel card (Bio-Rad DiaMed) and glass bead-based (Ortho Clinical Diagnostics) column agglutination technologies were used to screen for antibodies prospectively (group A) and for antibody identification in stored and fresh samples known to contain RBC antibodies retrospectively (group B). Untreated reagent RBCs and either papain-treated (Bio-Rad) or ficin-treated panel C cells (Ortho) were used for antibody identification.

Results

RBC-reactive antibodies were detected in 22 of 1000 group A samples, three of which tested positive only by gel card agglutination, and four only by glass bead agglutination (including one false positive each). Group B comprised 202 sera with known antibodies: 33 of these samples contained 36 antibodies detected only by gel card agglutination, whereas 9 samples contained antibodies detectable only by glass bead-based agglutination. Discrepancies mostly involved weak antibodies reactive by enzyme only. Two sera contained antibody mixtures that neither system detected completely. Of note, in antibody differentiation batches one and two, anti-Lu^a was reactive in 7 of 7 and 1 of 8 samples, respectively.

Conclusion

Both column agglutination tests for red cell antibodies had equal sensitivity and specificity with unstored samples. In stored samples, weak and enzyme-only antibodies were more frequently detected with the gel card system.

Red blood cell alloimmunization among hospitalized patients: transfusion reactions and low alloantibody identification rate

Background

Unexpected red blood cell alloantibodies can cause hemolytic transfusion reactions. In this study, the prevalence of alloimmunization, the rate of identification of alloantibodies and the rate of blood transfusion reactions among transfused patients were identified in a clinical emergency hospital in Brazil.

Methods

Transfusions and clinical records of patients who had a positive indirect antiglobulin test between January and December 2013 were analyzed.

Results

Of 1169 patients who received blood transfusions, 28 had positive indirect antiglobulin tests, with one patient having two positive tests at different times, resulting in 29 positive tests during the period of this study. Alloantibodies were identified in 58.6% (17/29) of the cases. In 27.5% (8/29), identification was inconclusive and it was not possible to confirm alloimmunization. The rate of red blood cell alloimmunization was 1.71% (21/1169). Of 21 cases of alloimmunization, four (19%) were unidentified due to an unusual agglutination profile. All identified alloantibodies were clinically significant (10/17 anti-Rh, 5/17 anti-Kell and 2/17 anti-MNS). In two patients who had positive indirect antiglobulin tests, one had an unidentified alloantibody, and the other had an inconclusive test and developed a hemolytic transfusion reaction.

Conclusion

The prevalence of clinically important red blood cell alloantibodies and hemolytic transfusion reactions among patients with unidentified alloantibodies suggests that specific laboratory techniques should be performed to identify alloantibodies in cases of pan-reactivity or autoantibodies to improve transfusion safety.

Clinical and epidemiological profile of alloimmunized and autoimmunized multi-transfused patients against red blood cell antigens in a blood center of Minas Gerais

Background

The large diversity of red blood cell antigens favors, especially in multi-transfused patients, the occurrence of autoimmunization and alloimmunization with the risk of hemolytic transfusion reactions. Thus, this study aimed to determine the rates of alloimmunization and autoimmunization in these individuals, as well as the types of alloantibodies and their systems, clinical and epidemiological aspects and the frequency of autoimmunity in alloimmunized and non-alloimmunized patients.

Methods

In a retrospective study, 153 multi-transfused patients from 2006 to 2014 were evaluated. Sixty-eight had onco-hematological diseases, 64 had hemoglobinopathies and 21 had chronic renal failure. Descriptive analyses were carried out with the proportions being compared using the chi-square test, with the significance level set at 5%.

Results

The Rh system was the most frequently involved (53.11%) and anti-E and anti-K (Kell system) were the most prevalent alloantibodies (21.87% each). Autoantibodies were found in ten patients (6.54%) with the percentages of autoimmunization in alloimmunized and non-alloimmunized individuals being 29.16% and 2.32%, respectively (p = 0.0001). There was a significant difference between autoimmunization and the number of transfusions (16.21% in 6–10 vs. 5.26% <6 vs. 2.56% >10; p = 0.0203) and diseases (19.04% in chronic renal failure vs. 6.25% in hemoglobinopathies vs. 2.94% in onco-hematological diseases; p = 0.0329).

Conclusion

The results show a strong correlation between alloimmunization and autoimmunization. Moreover, they reinforce the need for further studies on the clinical and epidemiological profile of multi-transfused patients in relation to alloimmunity and autoimmunity, especially the latter, for a better understanding of its etiopathogenesis and physiopathogenesis.

Red cell alloimmunization is associated with development of autoantibodies and increased red cell transfusion requirements in myelodysplastic syndrome

Up to 90% of patients with a myelodysplastic syndrome require red blood cell transfusion; nevertheless, comprehensive data on red cell alloimmunization in such patients are limited. This study evaluates the incidence and clinical impact of red cell alloimmunization in a large cohort of patients with myelodysplastic syndrome registered in the statewide South Australian-MDS registry. The median age of the 817 patients studied was 73 years, and 66% were male. The cumulative incidence of alloimmunization was 11%. Disease-modifying therapy was associated with a lower risk of alloimmunization while alloimmunization was significantly higher in patients with a revised International Prognostic Scoring System classification of Very Low, Low or Intermediate risk compared to those with a High or Very High risk (P=0.03). Alloantibodies were most commonly directed against antigens in the Rh (54%) and Kell (24%) systems. Multiple alloantibodies were present in 49% of alloimmunized patients. Although 73% of alloimmunized patients developed alloantibodies during the period in which they received their first 20 red cell units, the total number of units transfused was significantly higher in alloimmunized patients than in non-alloimmunized patients (90±100 versus 30±52; P<0.0001). In individual patients, red cell transfusion intensity increased significantly following alloimmunization (2.8±1.3 versus 4.1±2.0; P<0.0001). A significantly higher proportion of alloimmunized patients than non-alloimmunized patients had detectable autoantibodies (65% versus 18%; P<0.0001) and the majority of autoantibodies were detected within a short period of alloimmunization. In conclusion, this study characterizes alloimmunization in a large cohort of patients with myelodysplastic syndrome and demonstrates a signficant increase in red cell transfusion requirements following alloimmunization, most probably due to development of additional alloantibodies and autoantibodies, resulting in subclinical/clinical hemolysis. Strategies to mitigate alloimmunization risk are critical for optimizing red cell transfusion support.

Prevalence and risk factors for red blood cell alloimmunization in 175 children with sickle cell disease in a French university hospital reference centre

Patients with sickle cell disease (SCD) show a high prevalence of red blood cell (RBC) alloimmunization, but few studies have focused on children. We aimed to study the prevalence and risk factors of RBC alloimmunization in SCD children. We retrospectively analysed the medical and transfusion files for 245 SCD children hospitalized in our centre in 2014 and included 175 patients who had received at least one RBC unit in their lifetime. The main clinical and immuno-haematological characteristics of alloimmunized and non-alloimmunized patients were compared. The prevalence of alloimmunization was 13·7% [95% confidence interval (CI) (8·6-18·6)], and 7·4% [95% CI (3·5-11·3)] after excluding the probable irregular natural antibodies (anti-M, anti-Le^a , anti-Le^b , anti-Le^x ). Main risk factors for alloimmunization were increased number of RBC units received (median of 65 vs. 10 units per patient; P = 0·01) and the presence of one or more red cell autoantibodies (46·2% vs. 4·7%; P < 0·0001). The alloimmunization rate was higher for episodically transfused than chronically transfused patients (1·43 vs. 0·24/100 units received; P < 0·001). The presence of red cell autoantibodies appears to be a major risk factor for alloimmunization in SCD children and could justify specific transfusion guidelines.

Emergency transfusion of patients with unknown blood type with blood group O Rhesus D positive red blood cell concentrates: a prospective, single-centre, observational study

BACKGROUND

Emergency patients with unknown blood type usually receive O Rhesus D negative (RhD-) red blood cell concentrates until their blood group is determined to prevent RhD+ related adverse transfusion reactions. As 85% of individuals are RhD+, this consumption of O RhD- red blood cell concentrates contributes to shortages of O RhD- red blood cell concentrates, sometimes forcing transfusion of known RhD- patients with RhD+ red blood cell concentrates. Here we report the outcome of this transfusion policy transfusing all emergency patients with unknown blood type with O RhD+ red blood cell concentrates.

METHODS

In this prospective single-centre observational study done between Jan 1, 2001, and Dec 31, 2015, we assessed all consecutive RhD- patients at the University Medicine Greifswald who received RhD+ red blood cell concentrates (emergency patients with unknown blood type; and RhD- patients receiving RhD+ red blood cell concentrates during RhD- red blood cell concentrate shortages). No patients were excluded. The primary endpoint was anti-D allo-immunisation at 2 months follow-up or later. Patients were followed up and tested for immunisation against red blood cell antigens using the direct antiglobulin test and an antibody screen every 3-5 days for 4 weeks or until death, or hospital discharge. Surviving patients were screened for development of anti-D antibodies for up to 12 months (at the predefined timepoints 2, 3, 6, and 12 months) after RhD+ red blood cell transfusion.

FINDINGS

437 emergency patients, of whom 85 (20%) were RhD-, received 2836 RhD+ red blood cell concentrates. The overall risk of inducing anti-D antibodies (in all 437 recipients) was 17 (4%, 95% CI 2·44-6·14) of 437 (assuming all patients lost to follow-up developed anti-D allo-immunisation). During this period, 110 known RhD- patients received RhD+ red blood cell concentrates during RhD- red blood cell concentrate shortages. Of these, 29 (26%; 95% CI 19·0-35·3) developed anti-D allo-immunisation (assuming all patients lost to follow-up developed anti-D), which was significantly higher than in the emergency patients with unknown blood type (p<0·0001).

INTERPRETATION

Transfusing emergency patients with unknown blood type with O RhD+ red blood cell concentrates has a low risk of inducing anti-D antibodies (3-6%), but saves more than 10% of the total O RhD- red blood cell concentrate demand, thereby reducing shortage of O RhD- red blood cell concentrates, the need to transfuse known RhD-patients with RhD+ red blood cell concentrates, and thus the overall risk to induce anti-D allo-immunisation in the population. These findings should be considered for transfusion guidelines.

FUNDING

University Medicine Greifswald.

A Fatal Case of Immune Hyperhemolysis with Bone Marrow Necrosis in a Patient with Sickle Cell Disease

In patients with sickle cell disease, hyperhemolysis is a rare but life-threatening complication of transfusion. In this case report, we describe a 61 year-old woman with hemoglobin sickle cell (SC) disease and history of alloimmunization who developed hyperhemolysis associated with a transfusion. She was found to have a warm and a clinically-significant cold autoantibody. Severe anemia (Hb 2.7 g/dL) with reticulocytopenia and thrombocytopenia prompted a bone marrow biopsy, which demonstrated extensive bone marrow necrosis. Despite treatment, the bone marrow failure did not improve and the patient died on hospital day 38. This case illustrates the potential risks of transfusion in a patient with sickle cell disease, especially one with previous hemolytic reactions. While uncommon, hyperhemolysis can cause death, in this case by extensive bone marrow necrosis. In patients with sickle cell disease, judicious use of red cell transfusions with phenotypically-matched units can diminish, but never completely abrogate, the risks associated with transfusion.

Precautions surrounding blood transfusion in autoimmune haemolytic anaemias are overestimated

BACKGROUND

It is very evident that many precautions are taken regarding transfusion of red blood cells in patients with autoimmune haemolytic anaemia. Frequently, considerable efforts are made to examine the indication and serological compatibility prior to transfusion in such patients. However, at times, this may unnecessarily jeopardize patients who urgently require a red blood cell transfusion.

MATERIALS AND METHODS

Thirty-six patients with warm-type autoimmune haemolytic anaemia were included in this study. All patients had reactive serum autoantibodies and required blood transfusion. Standard serological assays were employed for the detection and characterization of antibodies to red blood cells.

RESULTS

A positive direct antiglobulin test was observed in all 36 patients, in addition to detectable antibodies in both the eluate and serum. Significant alloantibodies were detected in the serum samples of three patients (anti-c, anti-JK(a), and anti-E). In 32 patients, red blood cell transfusion was administered with no significant haemolytic transfusion reactions due to auto- and/or allo-antibodies. Due to overestimation of positive cross-matches three patients received no transfusion or delayed transfusion and died, and one patient died due to unrecognised blood loss and anaemia which was attributed to an ineffective red blood cell transfusion.

DISCUSSION

Many of the reported recommendations regarding transfusion of red blood cells in autoimmune haemolytic anaemia are highly questionable, and positive serological cross-matches should not result in a delay or refusal of necessary blood transfusions.

Harmless Pregnancy-Induced Warm Autoantibodies to Red Blood Cells

Background

There is little information concerning the development and significance of autoantibodies (aab) to red blood cells (RBCs) during pregnancy.

Methods

Unselected pregnant women were routinely screened for the presence of unexpected antibodies to RBCs using standard techniques.

Results

Between 2009 and 2013, 153,612 pregnant women were tested. The antibody screening test was positive in 1,721 women (1.12%). In 1,602 (1.04%) cases, immune and/or non-immune alloantibodies and cold-reactive aab were detected, whereas warm-reactive aab were found in 119 women (0.08%). In almost all cases, warm-reactive aab belonged to the IgG class. No evidence of the presence of significant haemolysis in affected women was observed.

Conclusion

Pregnant women may rarely develop aab to RBCs, which do not appear to cause haemolytic anaemia. Further clarification is required on the reasons behind the development of these aab and their clinical insignificance.

New Insights in the Pathogenesis of Autoimmune Hemolytic Anemia

Autoimmune hemolytic anemia (AIHA) is caused by the increased destruction of red blood cells (RBCs) by anti-RBC autoantibodies with or without complement activation. RBC destruction may occur both by a direct lysis through the sequential activation of the final components of the complement cascade (membrane attack complex), or by antibody-dependent cell-mediated cytotoxicity (ADCC). The pathogenic role of autoantibodies depends on their class (the most frequent are IgG and IgM), subclass, thermal amplitude (warm and cold forms),as well as affinity and efficiency in activating complement. Several cytokines and cytotoxic mechanisms (CD8+ T and natural killer cells) are further involved in RBC destruction. Moreover, activated macrophages carrying Fc receptors may recognize and phagocyte erythrocytes opsonized by autoantibodies and complement. Direct complement-mediated lysis takes place mainly in the circulations and liver, whereas ADCC, cytotoxicity, and phagocytosis occur preferentially in the spleen and lymphoid organs. The degree of intravascular hemolysis is 10-fold greater than extravascular one. Finally, the efficacy of the erythroblastic compensatory response can greatly influence the clinical picture of AIHA. The interplay and relative burden of all these pathogenic mechanisms give reason for the great clinical heterogeneity of AIHAs, from fully compensated to rapidly evolving fatal cases.

Clinically and/or Serologically Misleading Findings Surrounding Immune Haemolytic Anaemias

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

Treatment Options for Primary Autoimmune Hemolytic Anemia: A Short Comprehensive Review

Until now, treatment of primary autoimmune hemolytic anemia of the warm type (wAIHA) is primarily based on immunosuppression. However, many patients do not respond adequately to treatment, and treated patients may develop severe side effects due to uncontrolled, mixed and/or long-lasting immunosuppression. Unfortunately, the newly used therapeutic monoclonal antibodies are unspecific and remain frequently ineffective. Thus, development of a specific therapy for AIHA is necessary. The ideal therapy would be the identification and elimination of the causative origin of autoimmunization and/or the correction or reprogramming of the dysregulated immune components. Blood transfusion is the most rapidly effective measure for patients who develop or may develop hypoxic anemia. Although some effort has been made to guide physicians on how to adequately treat patients with AIHA, a number of individual aspects should be considered prior to treatment. Based on my serological and clinical experience and the analysis of evidence-based studies, we remain far from any optimized therapeutic measures for all AIHA patients. Today, the old standard therapy using controlled steroid administration, with or without azathioprine or cyclophosphamide, is, when complemented with erythropoiesis-stimulating agents, still the most effective therapy in wAIHA. Rituximab or other monoclonal antibodies may be used instead of splenectomy in therapy-refractory patients.

'Chameleonic' Serological Findings Leading to Life-Threatening Hemolytic Transfusion Reactions

Background

The phenomena of co-incidence of transfusion-induced allo- and autoantibodies, blockage and/or loss of red blood cell (RBC) antigens are conspicuous and may result in confusion and misdiagnosis.

Case Report

A 67-year-old female was transferred to the intensive care unit due to hemolysis which developed 2 days following transfusion of three Rh(D)-negative RBC units in the presence of strongly reactive autoantibodies. Standard serological testing and genotyping were performed. Upon arrival, the patient was typed as Ccddee. Her hemolysis was decompensated, and an immediate blood transfusion was required. In addition, direct and indirect antiglobulin tests (DAT and IAT) as well as the eluate were strongly positive. Emergency transfusion of Rh(D)-negative RBCs resulted in increased hemolysis and renal failure. An exhaustive testing revealed anti-D, anti-c, CCddee phenotype and CCD.ee genotype. Three units of cryopreserved CCddee RBCs were transfused, and the patient's condition immediately improved. The discrepancy between Rh-D phenotyping and genotyping was likely caused by masking of the D-epitopes by the autoantibodies. In fact, further enquiry revealed that the patient had been phenotyped as Rh(D)-positive 6 months ago and had been transfused at that time following hip surgery.

Conclusion

The phenomena of transfusion-induced autoantibodies, masked alloantibodies, antigen blockage and/or loss are rare but important features which should be considered in patients presenting with autoimmune hemolytic anemia and/or hemolytic transfusion reactions.

[Anti-erythrocyte and anti-HLA immunization in hemoglobinopathies]

AIM

Evaluate the anti-erythrocyte and anti-HLA immunization rates in hemoglobinopathies.

PATIENTS AND METHODS

Cross-sectional study (October 2009-March 2010) on 83 patients followed for hemoglobinopathies. The irregular antibodies research is realized by two techniques: indirect Coombs and enzymatic technique on gel cards. The search for anti-HLA class I antibodies is done by complement dependent lymphocytotoxicity.

RESULTS

The mean age was 30 years (14-64 years), the sex ratio M/F is 0.84. Our series included 42 cases of sickle cell disease (29 homozygous sickle cell anemia and 13 sickle-thalassemia) and 41 cases of thalassemia syndromes (26 major and 15 intermediate). The anti-erythrocyte alloimmunization rate is 10.84% without difference between thalassemia syndromes and sickle cell disease. The autoimmunization rate (22.89%) is higher in thalassemia syndromes (41.46%) than in the sickle cell disease (7.14%) (P<0.001). The anti-HLA immunization rate is 31.6% without difference between thalassemia syndromes and sickle cell disease. The young age, transfusion at a young age and the total number of transfusions are the factors that increase the risk of anti-erythrocyte autoimmunization. No clinicobiological parameter does influence the anti-erythrocyte and anti-HLA alloimmunization. There is no significant association between anti-erythrocyte and anti-HLA immunization.

CONCLUSION

The erythrocyte and anti-HLA anti-immunization rates are high in our series. Preventive strategy is needed to ensure optimal blood safety.

Prevalence and Specificity of RBC Alloantibodies in Indian Patients Attending a Tertiary Care Hospital

Background. Red blood cell (RBC) alloimmunization results from genetic disparity of RBC antigens between donor and recipients. Data about alloimmunization rate in general patient population is scarce especially from resource limited countries. We undertook this study to determine prevalence and specificity of RBC alloantibodies in patients admitted in various clinical specialties at a tertiary care hospital in North India. Methods. Antibody screening was carried out in 11,235 patients on automated QWALYS 3 platform (Diagast, Loos, France). Antibody identification was carried out with an 11-cell identification panel (ID-Diapanel, Diamed GmbH, Switzerland). Results. The overall incidence of RBC alloimmunization in transfused patients was 1.4% (157/11235), with anti-E being the most common specificity (36.3%), followed by anti-D (16%), anti-c (6.4%), anti-c + E (6.4%), anti-C + D (5.1%), and anti-K (4.5%). The highest incidence of alloimmunization was observed in hematology/oncology patients (1.9%), whereas in other specialties the range was 0.7–1%. Conclusion. As alloimmunization complicates the transfusion outcomes, authors recommend pretransfusion antibody screening and issue of Rh and Kell matched blood to patients who warrant high transfusion requirements in future.

Autoimmune hemolytic anemia after allogeneic hematopoietic stem cell transplantation: analysis of 533 adult patients who underwent transplantation at King's College Hospital

Autoimmune hemolytic anemia (AIHA) is a recognized complication of hematopoietic stem cell transplantation (HSCT); it is often refractory to treatment and carries a high mortality. To improve understanding of the incidence, risk factors, and clinical outcome of post-transplantation AIHA, we analyzed 533 patients who received allogeneic HSCT, and we identified 19 cases of AIHA after HSCT (overall incidence, 3.6%). The median time to onset, from HSCT to AIHA, was 202 days. AIHA was associated with HSCT from unrelated donors (hazard ratio [HR], 5.28; 95% confidence interval [CI], 1.22 to 22.9; P = .026). In the majority (14 of 19; 74%) of AIHA patients, multiple agents for treatment were required, with only 9 of 19 (47%) patients achieving complete resolution of AIHA. Patients with post-transplantation AIHA had a higher overall mortality (HR, 2.48; 95% CI, 1.33 to 4.63; P = .004), with 36% (4 of 11 cases) of deaths attributable to AIHA.

Clearance of pathological antibodies using biomimetic nanoparticles

Pathological antibodies have been demonstrated to play a key role in type II immune hypersensitivity reactions, resulting in the destruction of healthy tissues and leading to considerable morbidity for the patient. Unfortunately, current treatments present significant iatrogenic risk while still falling short for many patients in achieving clinical remission. In the present work, we explored the capability of target cell membrane-coated nanoparticles to abrogate the effect of pathological antibodies in an effort to minimize disease burden, without the need for drug-based immune suppression. Inspired by antibody-driven pathology, we used intact RBC membranes stabilized by biodegradable polymeric nanoparticle cores to serve as an alternative target for pathological antibodies in an antibody-induced anemia disease model. Through both in vitro and in vivo studies, we demonstrated efficacy of RBC membrane-cloaked nanoparticles to bind and neutralize anti-RBC polyclonal IgG effectively, and thus preserve circulating RBCs.

Diagnostic and therapeutic challenges of primary autoimmune haemolytic anaemia in children

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

Clinical management of patients receiving cell-based immunoregulatory therapy

Administering immunoregulatory cells as medicinal agents is a revolutionary approach to the treatment of immunologically mediated diseases. Isolating, propagating, and modifying cells before applying them to patients allows complementation of specific cellular functions, which opens astonishing new possibilities for gain-of-function antigen-specific treatments in autoimmunity, chronic inflammatory disorders, and transplantation. This critical review presents a systematic assessment of the potential clinical risks posed by cell-based immunotherapy, focusing on treatment of renal transplant recipients with regulatory macrophages as a concrete example.

Perioperative management of an IgA-deficient recipient of a double-lung transplant

PURPOSE

When exposed in the perioperative period to blood components containing immunoglobulin (Ig)A IgA-sensitized IgA-deficient patients are at an increased risk of transfusion-associated anaphylaxis. We present the case of an IgA-deficient patient whose candidacy for double-lung transplantation was under review in the preoperative period.

CLINICAL FEATURES

A 49-yr-old patient with end-stage chronic obstructive lung disease secondary to deficiencies in IgA and IgG subclasses was being assessed for double-lung transplantation. Early recognition of the ramifications of perioperative transfusion prompted consultation with the transfusion medicine service. This in turn facilitated specialized laboratory testing and the coordinated provision of appropriate blood products for the unpredictable date of transplantation. The theoretical systemic risks of a non-IgA-deficient graft on the sensitized IgA-deficient host were considered. To affirm the patient's candidacy for transplantation, he was ultimately challenged preoperatively with IgA-containing products in a controlled intensive-care setting.

CONCLUSION

Through a multidisciplinary approach [corrected], a successful transplantation outcome was achieved in an IgA-deficient patient undergoing major surgery. Strategies to mitigate risk include the procurement and transfusion of IgA-deficient components, which may be challenging or untenable in emergent perioperative settings.

Beta thalassemia major in a developing country: epidemiological, clinical and evolutionary aspects

Beta-thalassemia major (TM) remains to be one of the major health problems particularly in developing countries. Tunisia is a part of the Mediterranean countries mostly affected by this disease which is highly concentrated in small towns in families with low-income earners. The main objectives of this study are to provide a description of the demographic, clinical features and transfusion-related complications in patients with TM living in Tunisia. A standardized questionnaire was sent to clinicians throughout 33 different medical institutions caring for thalassemic patients. 391 transfusion dependant thalassemic patients with a median age of 10.7 years (range 3 months- 31 years) were included in the study. The majority originated from the north west of the country. A moderate iron overload between 1501 and 2500 ng/ml was found in 61patients, while 81 patients (26.9%) had a ferritin level more than 2500 ng/ml and greater than 5000ng/ml in 21 patients (6.9%). 51 patients died from complications related to their disease. Heart failure was the main cause of death. The incidence of cardiac, endocrine, and infectious complications will be reviewed. Preventive measures such as health education, carrier screening and premarital screening remain the best ways for lowering the incidence of these diseases, which might be reflected in financial saving, social s and health benefits.

Alternative blood products and clinical needs in transfusion medicine

The primary focus of national blood programs is the provision of a safe and adequate blood supply. This goal is dependent on regular voluntary donations and a regulatory infrastructure that establishes and enforces standards for blood safety. Progress in ex vivo expansion of blood cells from cell sources including peripheral blood, cord blood, induced pluripotent stem cells, and human embryonic stem cell lines will likely make alternative transfusion products available for clinical use in the near future. Initially, alloimmunized patients and individuals with rare blood types are most likely to benefit from alternative products. However, in developed nations voluntary blood donations are projected to be inadequate in the future as blood usage by individuals 60 years and older increases. In developing nations economic and political challenges may impede progress in attaining self-sufficiency. Under these circumstances, ex vivo generated red cells may be needed to supplement the general blood supply.

High frequency of autoimmunization among transfusion-dependent Tunisian thalassaemia patients

BACKGROUND

Limited data are available on the frequency of RBC alloimmunization and autoimmunization in transfusion-dependent Tunisian β thalassaemia patients.

MATERIALS AND METHODS

We analyzed the clinical and transfusion records of 130 patients (57 females and 73 males; mean age 119 months; range 12-11 months) with β thalassaemia major and who had regular blood transfusions for periods ranging from 12 to 311 months.

RESULTS

Of the 130 patients, ten (7.7%) developed RBC alloantibodies. The most common alloantibodies were directed against antigens in the Rh systems. Erythrocyte-autoantibodies as determined by a positive direct antiglobulin Coombs test, developed in 52(40%) patients with and without underlying RBC alloantibodies, thereby causing autoimmune haemolytic anaemia in eleven patients (21%).

CONCLUSIONS

Autoimmunization to erythrocyte antigens is a frequent complication in patients with β thalassaemia major. Several factors might have contributed to the high autoimmunization rate observed in this study, including non phenotypic blood exposure and alloantibody formation prior to positive Coombs test.

Under HEMA conditions, self-replication of human erythroblasts is limited by autophagic death

The number of erythroblasts generated ex-vivo under human-erythroid massive-amplification conditions by mononuclear cells from one unit of adult blood (~10(10)) are insufficient for transfusion (~10(12) red cells), emphasizing the need for studies to characterize cellular interactions during culture to increase erythroblast production. To identify the cell populations which generate erythroblasts under human-erythroid-massive-amplification conditions and the factors that limit proliferation, day 10 non-erythroblasts and immature- and mature-erythroblasts were separated by sorting, labelled with carboxyfluorescein-diacetate-succinimidyl-ester and re-cultured either under these conditions (for proliferation, maturation and/or apoptosis/autophagy determinations) or in semisolid media (for progenitor cell determination). Non-erythroblasts contained 54% of the progenitor cells but did not grow under human-erythroid-massive-amplification conditions. Immature-erythroblasts contained 25% of the progenitor cells and generated erythroblasts under human-erythroid-massive-amplification conditions (FI at 48 h=2.57±1.15). Mature-erythroblasts did not generate colonies and died in human-erythroid-massive-amplification conditions. In sequential sorting/re-culture experiments, immature-erythroblasts retained the ability to generate erythroblasts for 6 days and generated 2-5-fold more cells than the corresponding unfractionated population, suggesting that mature-erythroblasts may limit erythroblast expansion. In co-cultures of carboxyfluorescein-diacetate-succinimidyl-ester-labelled-immature-erythroblasts with mature-erythroblasts at increasing ratios, cell numbers did not increase and proliferation, maturation and apoptotic rates were unchanged. However, Acridine Orange staining (a marker for autophagic death) increased from ~3.2% in cultures with immature-erythroblasts alone to 14-22% in cultures of mature-erythroblasts with and without immature-erythroblasts. In conclusion, these data identify immature-erythroblasts as the cells that generate additional erythroblasts in human-erythroid-massive-amplification cultures and autophagy as the leading cause of death limiting the final cellular output of these cultures.

Increased detection of clinically significant antibodies and decreased incidence of delayed haemolytic transfusion reaction with the indirect antiglobulin test potentiated by polyethylene glycol compared to albumin: a Japanese study

BACKGROUND

The indirect antiglobulin test (IAT) can be potentiated by agents such as polyethylene glycol (PEG-IAT) and albumin (Alb-IAT). PEG-IAT is generally regarded as superior to Alb-IAT for the detection of clinically significant red blood cell (RBC) antibodies. However, supporting data come from Caucasian-dominant populations. Non-Caucasian populations should be investigated as well.

MATERIAL AND METHODS

In this single-centre, retrospective, sequential study, Alb-IAT was used from 1989 to 1996 (8 years) and PEG-IAT from 1997 to 2008 (12 years). Pre-transfusion RBC alloantibody detection rates and specificity, post-transfusion alloantibody production, and the incidence of delayed haemolytic transfusion reaction were assessed and compared for the two periods.

RESULTS

Although overall RBC alloantibody detection rates were comparable, PEG-IAT more frequently detected clinically significant antibodies such as anti-E, anti-Fy(b), and anti-Jk(a), and less frequently detected insignificant antibodies such as anti-Le(b) and anti-P(1). New alloantibodies emerged comparably during the two periods. Delayed haemolytic transfusion reaction was less frequent during the PEG-IAT period (0.30% versus 0.12%, p<0.05).

CONCLUSION

PEG-IAT was superior in the detection of clinically significant antibodies, reduced the detection of insignificant antibodies, and prevented delayed haemolytic transfusion reaction better than Alb-IAT among Japanese transfusion recipients in this retrospective survey of limited power.

Antibody development in pediatric sickle cell patients undergoing erythrocytapheresis

BACKGROUND

Erythrocytapheresis, or red blood cell exchange transfusion (RBCX), with donor red blood cell (RBC) units is now increasingly used in the treatment of acute and chronic complications of sickle cell disease (SCD). As in all transfusions, RCBX carries a risk of immunization against foreign antigen on transfused cells. However, by selecting donor units with RBC phenotypes similar to the patient, the risk of allo- and autoimmunization can be reduced.

PROCEDURE

The formation of RBC alloantibodies and/or autoantibodies in 32 multitransfused pediatric SCD patients undergoing monthly RBCX over a 11-year period (12/1998 to 12/2009) was evaluated utilizing a retrospective patient chart review at Kosair Children's Hospital, Louisville, Kentucky.

RESULTS

After starting C, E, K antigen-matched RBCX, the rate of clinically significant allo-immunization decreased from 0.189/100 to 0.053/100 U, with a relative risk of 27.9%. Likewise, the rate of autoimmunization decreased from 0.063/100 to 0.035/100 U, with a relative risk of 55.9%.

CONCLUSION

After controlling for clinically insignificant antibodies, our auto- and alloimmunization rate was much less than previously reported values. In addition, the incidence of clinically significant allo- and autoimmunization decreased in our patient population after starting minor antigen-matched RBCX. These results suggest that by matching selected RBC phenotypes, there may be an association in the risk of allo- and autoimmunization of multi-transfused SCD patients.

HLA alloimmunization is associated with RBC antibodies in multiply transfused patients with sickle cell disease

BACKGROUND

Alloimmunization to minor red blood cell (RBC) antigens occurs commonly in sickle cell disease (SCD). Patients with alloimmunization demonstrate increased risk for new alloantibody formation with subsequent transfusion. Alloimmunization to human leukocyte antigens (HLA) can occur with RBC transfusion and may result in graft rejection during stem cell or organ transplantation. The prevalence and risk factors for HLA alloimmunization in multiply transfused pediatric SCD patients are unknown.

PROCEDURE

A cross-sectional study of HLA alloimmunization in SCD patients aged 3-21 years with a history of >or=3 RBC transfusions was performed to test the hypothesis that HLA alloimmunization is associated with RBC alloimmunization. Antibodies to class I and class II HLA were measured by Flow Panel Reactive Antibody (FlowPRA).

RESULTS

Seventy-three SCD patients (30 with RBC antibodies) were tested. HLA antibodies were detected in 25/73 (34%) patients; class I HLA antibodies occurred in 24/73 (33%) and class II HLA antibodies occurred in 3 (4%). Among patients with RBC antibodies, 16/30 (53%) had HLA antibodies, while 9/43 (21%) patients without RBC antibodies had HLA antibodies (OR 4.32 [1.6-12.1]). In a multivariate analysis, antibodies to RBC antigens were an independent predictor of HLA alloimmunization (P = 0.041). The association of RBC and HLA immunization was strongest among patients with no history of chronic transfusion therapy.

CONCLUSIONS

This analysis is the first description of HLA alloimmunization in pediatric SCD patients who receive primarily leukoreduced RBC transfusions and demonstrates that HLA alloimmunization tendency is associated with antibodies to RBC antigens.

Geoepidemiology of autoimmune hemolytic anemia

Autoantibodies against red blood cell antigens are considered the diagnostic hallmark of AIHA: Direct antiglobulin test (DAT) completed by cytofluorometry and specific diagnostic monoclonal antibodies (mAbs) allow for a better understanding of autoimmune hemolytic anemia (AIHA) triggers. Once B-cell tolerance checkpoints are bypassed, the patient loses self-tolerance, if the AIHA is not also caused by an possible variety of secondary pathogenic events such as viral, neoplastic and underlying autoimmune entities, such as SLE or post-transplantation drawbacks; treatment of underlying diseases in secondary AIHA guides ways to curative AIHA treatment. The acute phase of AIHA, often lethal in former times, if readily diagnosed, must be treated using plasma exchange, extracorporeal immunoadsorption and/or RBC transfusion with donor RBCs devoid of the auto-antibody target antigen. Genotyping blood groups (www.bloodgen.com) and narrowing down the blood type subspecificities with diagnostic mAbs help to define the triggering autoantigen and to select well compatible donor RBC concentrates, which thus escape recognition by the autoantibodies.

Transfusion medicine in a developing country - alloantibodies to red blood cells in multi-transfused patients in Saudi Arabia

BACKGROUND

Multiple transfusions are frequently complicated by alloimmunization. This retrospective study aims to determine whether alloimmunization could be accounted for by racial differences between donors and recipients.

MATERIALS AND METHODS

The development of alloantibodies were determined in 68 multi-transfused patients (thalassaemia, n=38) and (sickle cell anemia, n=30).

RESULTS

The overall frequency of alloantibody formation in our patients is 22.06%. Thirteen patients received blood from the same ethnic group (Arab) and none developed antibodies, while of 47 patients who received multi-ethnic blood, 10 developed alloantibodies.

CONCLUSIONS

Alloantibodies formation can be reduced by limiting the transfusion of RBC, collected from donors of the same ethnic origin.

Transfusion-induced autoantibodies and differential immunogenicity of blood group antigens: a novel hypothesis

Blood bank serology has identified hundreds of red blood cell (RBC) antigens contained within numerous blood group systems. Although most blood group antigens are defined by amino acid polymorphisms in the extracellular domain of membrane proteins, it is also possible that additional nonexofacial polymorphisms (NEPs) may exist within cytoplasmic or transmembrane domains. To assess this possibility, we analyzed several blood group molecules by searching the SNPper database for nonsynonymous single-nucleotide polymorphisms. We report the identification of a number of NEPs in the Kell, Kidd, and Duffy molecules. Because the identified NEPs are not exposed on the surface of intact RBCs and are, thus, not accessible to recipient antibodies, they would neither be detected by blood bank serology in vitro, nor would they be recognized targets in hemolytic transfusion reactions in vivo. The presentation of peptides containing NEPs by recipient MHC Class II molecules, however, would nevertheless produce helper T-cell epitopes. In addition to identifying NEPs in human blood group molecules, we explore a novel hypothesis that the presence of NEPs contributes to the immunogenicity of blood group antigens. We further hypothesize that NEPs provide a mechanism by which transfusion can lead to anti-RBC autoantibodies, which are known to occur in humans after transfusion. The scientific basis, existing evidence, approaches to testing, and predicted biology of this hypothesis are presented.

Association between alloantibody specificity and autoantibodies to red blood cells

BACKGROUND

Alloantibodies (ALLOs) to red blood cells (RBCs) are frequently associated with autoantibodies (AABs). An association between ALLO specificity and AABs has not yet been described.

STUDY DESIGN AND METHODS

All patients and healthy blood donors screened for RBC antibodies between 2000 and 2006 were included. The odds ratio (OR) for ALLOs in patients with AABs compared to those without AABs was correlated with the OR of general ALLO prevalence in patients with AABs (normalized OR).

RESULTS

ALLOs were found in 4,626 of 204,330 patients and healthy blood donors (2.3%). The ALLOs were associated with AABs in 413 cases (8.9%). Among the specificities, anti-S with a normalized OR of 2.9 was overrepresented. This was most evident in pregnant women who showed a normalized OR of 15.1 for anti-S and AABs. The normalized OR revealed an additional association between Rh antibodies and AABs. No association was found between ALLOs to the Kell glycoprotein, Duffy protein, Lewis, or glycophorin A (M/N) and AABs.

CONCLUSION

The majority of associated ALLOs and AABs are directed against neighboring antigens of the Rh complex and glycophorin B.