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1.  Study of red blood cell alloimmunization in multitransfused thalassemic children of Jammu region 
Thalassemia is one of the most common genetic disorder of hemoglobin synthesis in Jammu region. Although RBC transfusion is life saving for these patients, it may be associated with some complications like RBC alloimmunization. Thus, the aim of this study was to determine the frequency of alloimmunization and the most common alloantibodies involved.
Material and Methods:
This was a descriptive study involving a total of 70 thalassemic patients in the age range of 2-17 years receiving regular blood transfusions, registered at SMGS Blood Bank, Jammu. Relevant clinical and laboratory data was collected with reference to age at the start of transfusions, total number of transfusions received and splenectomy status. Antibodies screening, antibody identification, and cross matching was done on allpatient samples included in the study, during the period between November 2009 and October 2010.
In this study, a total of six alloantibodies six patients (8.5%) and one autoantibody (1.42%) was detected. All identified alloantibodies belonged to Rh system (i.e. anti-E, in 3 patients (50%), anti D, in one patient (16.66%)) and Kell system (anti-K, in two patients (33.34%)). Higher frequency of alloimmunization was found, with increase in number of transfusions and in those who received transfusions after 1 year of age. Alloimmunization was not significantly associated with gender and splenectomy status (P-value > 0.05).
Red cell alloantibodies developed in 8.5% of thalassemic patients and 1.42% had autoantibodies. The most common alloantibodies identified were anti Rh system antibodies (anti-E and anti-D) present in 50% and 16.66% of patients respectively. Alloimmunization is not an uncommon problem faced by blood banks and finding compatible units for regularly transfused thalassemic patients may become very difficult. In order to reduce alloimmunization, a policy for performing extended red cell phenotyping of these patients is essential and at least antigen E and Kell negative blood should be provided for transfusion to these patients.
PMCID: PMC4339939  PMID: 25722579
Alloimmunization; multitransfused; thalassemia
2.  Alloimmunization and autoimmunization in transfusion dependent thalassemia major patients: Study on 319 patients 
The development of anti-red blood cell antibodies (both allo-and autoantibodies) remains a major problem in thalassemia major patients. We studied the frequency of red blood cell (RBC) alloimmunization and autoimmunization among thalassemia patients who received regular transfusions at our center and analyzed the factors, which may be responsible for development of these antibodies.
Materials and Methods:
The study was carried out on 319 multiply transfused patients with β-thalassemia major registered with thalassemia clinic at our institute. Clinical and transfusion records of all the patients were examined for age of patients, age at initiation of transfusion therapy, total number of blood units transfused, transfusion interval, status of splenectomy or other interventions. Alloantibody screening and identification was done using three cell and 11 cell panel (Diapanel, Bio-rad, Switzerland) respectively. To detect autoantibodies, autocontrol was carried out using polyspecific coombs (IgG + C3d) gel cards.
Eighteen patients out of total 319 patients (5.64%) developed alloantibodies and 90 (28.2%) developed autoantibodies. Nine out of 18 patients with alloantibodies also had autoantibodies. Age at first transfusion was significantly higher in alloimmunized than non-immunized patients (P = 0.042). Out of 23 alloantibodies, 52.17% belonged to Rh blood group system (Anti-E = 17%, Anti D = 13%, Anti-C = 13%, Anti-Cw = 9%), 35% belonged to Kell blood group system, 9% of Kidd and 4% of Xg blood group system.
Alloimmunization was detected in 5.64% of multitransfused thalassemia patients. Rh and Kell blood group system antibodies accounted for more than 80% of alloantibodies. This study re-emphasizes the need for RBC antigen typing before first transfusion and issue of antigen matched blood (at least for Rh and Kell antigen). Early institution of transfusion therapy after diagnosis is another means of decreasing alloimmunization.
PMCID: PMC4140069  PMID: 25161344
Alloimmunization; autoimmunization; thalassemia major; transfusion
3.  Prevalence and specificities of red cell alloantibodies among blood recipients in the Malaysian state of Kelantan 
Red blood cell (RBC) alloantibodies may be formed following exposure to RBC antigens. In most cases, the alloimmunization develops during pregnancy or from previous blood transfusions. The RBC antigens and their alloantibodies vary among different human populations and ethnic groups, and they do have a clinical significance for their adverse immunological reactions.
This study aimed at studying the prevalence of RBC alloantibodies at the Blood Transfusion Unit of Hospital Raja Perempuan Zainab II in Kota Bharu, Malaysia.
Patients and Methods:
A cross-sectional study was performed utilizing data obtained in the years 2007 and 2008. Data of antibody screening tests from 5719 patients were examined.
Results and Discussion:
The overall prevalence of alloimmunization was 65 (1.13%). The majority of these had a single alloantibody (76.9%), whereas the remaining 23.1% had multiple antibodies. The anti-E antibody comprised the most common alloantibody (24.6%) followed by the anti-Lewis (a) antibodies (18.5%) and the anti-M antibody (13.8%). There were more female recipients than males.
It was concluded that the findings of this work have been comparable with other published works, and that the main factors associated with alloantibody formation were multiple transfusions and pregnancies. The study also emphasizes the necessity for carrying out immunohematology studies prior to every blood transfusion especially in cases that require multiple transfusions for a long period of time such as in thalassemia patients.
PMCID: PMC3082716  PMID: 21572715
RBC antigens; alloantibodies; blood transfusion
4.  Frequency & specificity of RBC alloantibodies in patients due for surgery in Iran 
Background & objectives:
Red blood cell alloimmunization is common in patients receiving multiple blood transfusions. Since the probability of repeat transfusion increases with longer life expectancy, it is important to study to which extent alloimmunized patients with a history of transfusion are prone to form alloantibodies after transfusion events. The aim of this study was to retrospectively analyze the alloimmunization against RBCs among transfused patients who were to undergo elective surgery in Tehran, Iran.
A total of 3092 occasionally transfused patients, who were to undergo elective surgery, in four hospitals in Tehran were included in the study. For patients with alloantibodies, the data about sex, date of birth, history of transfusion, surgery, abortion and alloantibody specificity were collected.
Clinically significant alloantibodies were found in 30 patients. The presence of positive antibodies in the patients for whom cross-match had been done was one per cent. Most of them had surgery history or transfusion record during the preceding year. The three most frequent alloantibodies were anti-K (23.53%), anti- E (20.59%) and anti-c (17.56%).
Interpretation & conclusions:
The most common clinically significant alloantibodies identified in men and women were anti-K and anti-E, respectively. The most common causes of alloimmunization for men were surgery history and transfusion record and for women pregnancy.
PMCID: PMC3788212  PMID: 24056603
Alloimmuization; RBC antigens and antibodies; serological testing; transfusion-surgery
5.  Transfusion Complications in Thalassemia Patients: A Report from the Centers for Disease Control and Prevention (CDC) 
Transfusion  2013;54(4):972-971.
Background and Study Objectives
Transfusions are the primary therapy for thalassemia but have significant cumulative risks. In 2004, the Centers for Disease Control and Prevention (CDC) established a national blood safety monitoring program for thalassemia. The purpose of this report is to summarize the patient population as well as previous non-immune and immune transfusion complications at the time of enrollment into the program. A focus on factors associated with allo- and auto-immunization in chronically transfused patients and a description of blood product preparation and transfusion practices at the participating institutions are included.
Study Design and Methods
The CDC Thalassemia Blood Safety Network is a consortium of thalassemia centers, longitudinally following patients to determine transfusion-related complications. Enrollment occurred from 2004 through 2012 and annual data collection is ongoing. Demographic data, transfusion history, and previous transfusion and non-transfusion complications were summarized for patients enrolled between 2004 and 2011. Logistic analyses of factors associated with allo- and auto-immunization were developed. Summary statistics of infections reported at the time of enrollment were also calculated.
The race/ethnicity of the 407 thalassemia patients enrolled in the Network was predominantly Asian or Caucasian and 27% were immigrants. The average age was 22.3 years ± 13.2 and patients received an average total number of 149 ± 103.4 units of red blood cells. Iron-induced multi-organ dysfunction was common despite chelation. At study entry, 86 patients had previously been exposed to possible transfusion-associated pathogens, including Hepatitis-C (61), Hepatitis B (20), Hepatitis A (3), Parvovirus (9), HIV (4), malaria (1), staphylococcus aureus (1) and babesia (1). As 27% of the population was born outside of the United States (India, Pakistan, Thailand, China, Vietnam and Iran accounting for 57%), the source of infection cannot be unequivocally tied to transfusion. In total, 24% of transfused patients were reported to have possible transfusion-associated pathogens. Transfusion reactions occurred in 48% of patients, including allergic, febrile, and hemolytic; 19% of transfused patients were alloimmunized (defined as a having an antibody to a foreign red blood cell antigen). The most common antigens were E, Kell and C. One hemolytic reaction to an anti-Mia antibody was noted. Years of transfusion was the strongest predictor of alloimmunization. However, initiating transfusions in infancy may induce immune tolerance. Autoantibodies occurred in 6.5% and were predicted by previous alloimmunization (p < .0001). Local institutional transfusion policies, rather than patient characteristics, were the major determinants in the preparation of red-blood cells for transfusion.
Hemosiderosis and immunologic and non-immunologic transfusion reactions are major problems in thalassemia patients. Infections continue to be a problem in thalassemia and new pathogens have been noted. National transfusion guidelines for red cell phenotyping and preparation are needed in thalassemia to decrease transfusion-related morbidity.
PMCID: PMC4410835  PMID: 23889533
Transfusion Practices (Oncology- Hematology); Hematology – Red Cells; Transfusion Complications - Non Infectious
6.  Alloimmunization screening after transfusion of red blood cells in a prospective study 
Several irregular red blood cell alloantibodies, produced by alloimmunization of antigens in transfusions or pregnancies, have clinical importance because they cause hemolysis in the fetus and newborn and in transfused patients.
a prospective analysis of patients treated by the surgical and clinical emergency services of Hospital de Clínicas of the Universidade Federal do Triângulo Mineiro (HC/UFTM), Brazil was performed to correlate alloimmunization to clinical and epidemiological data.
Blood samples of 143 patients with initial negative antibody screening were collected at intervals for up to 15 months after the transfusion of packed red blood cells. Samples were submitted to irregular antibody testing and, when positive, to the identification and serial titration of alloantibodies. The Fisher Exact test and Odds Ratio were employed to compare proportions.
Fifteen (10.49%) patients produced antibodies within six months of transfusion. However, for 60% of these individuals, the titers decreased and disappeared by 15 months after transfusion. Anti-K antibodies and alloantibodies against antigens of the Rh system were the most common; the highest titer was 1:32 (anti-K). There was an evident correlation with the number of transfusions.
Given the high incidence of clinically important red blood cell alloantibodies in patients transfused in surgical and clinical emergency services, we suggest that phenotyping and pre-transfusion compatibilization for C, c, E, e (Rh system) and K (Kell system) antigens should be extended to all patients with programmed surgeries or acute clinical events that do not need emergency transfusions.
PMCID: PMC3459635  PMID: 23049421
Blood transfusion; Blood group antigens; Hemolysis; Immunophenotyping; Emergencies
7.  Prevalence and specificities of red cell alloantibodies in transfusion-dependent beta thalassemia patients in Yazd 
Multiple transfusions in thalassemia patients may lead to antibody production against blood group antigens and hemolytic transfusion reaction might occur. In this study, antibody screening test was performed by tube and gel methods to determine the prevalence and specificity of alloantibodies in thalassemia patients.
Materials and Methods
In this cross-sectional study, overall of 100 thalassemia patients from Yazd thalassemia clinic were recruited from July to September 2013. Two blood samples with volume of 6 ml were collected from each patient for standard tube and gel method antibody screening tests and a questionnaire consisting of demographic, health and blood transfusion status was completed.
Out of 100 cases, 54 were female (54%) and 46 male (46%). The patients' age mean was 14.97±7.91 years with 2 to 33 years age range. Only 4% (n=4) had developed alloantibodies. (One patient developed dual alloantibody (Anti-C and Anti-D) and three patients developed single alloantibody (Anti-K)).Gel method detected 4 patients with alloantibody but in two patients not detected by the standard tube method.
The prevalence of RBC alloantibody production in this study was less than most previous studies. Anti-K was the most prevalent alloantibody in thalassemia patients in Yazd. It seems Rh and Kell blood group phenotyping in a newly diagnosed thalassemia patient and selection of matched blood for transfusion is very important.
PMCID: PMC4475630  PMID: 26131348
Exchange Transfusion; Overdose; Thalassemia
8.  Resolution of alloimmunization and refractory autoimmune hemolytic anemia in a multi-transfused beta-thalassemia major patient 
Beta-thalassemia is one of the most prevalent autosomal disorders, which affect more than 400,000 newborn per year worldwide. In India, the carrier rate of beta-thalassemia varies from 3-17%. The overall rate of alloimmunization in thalassemia patients has been reported to be 5-30% in the world, which is mostly contributed by the alloimmunization to minor blood group antigen. Among Asians, the incidence of red cell alloimmunization is 22%. The recommended treatment for beta-thalassemia major is regular blood transfusion every 3 to 4 weeks. The development of anti-red cell antibodies (alloantibodies and/or autoantibodies) can significantly complicate transfusion therapy. Alloantibodies are commonly associated with red cell hemolysis. Red cell autoantibodies appear less frequently, but they can result in clinical hemolysis called autoimmune hemolytic anemia (AIHA), and in difficulty in cross-matching blood. Patients with autoantibodies may have a higher transfusion rate and often require immunosuppressive drugs or alternative treatments including intravenous immunoglobulin (IVIg) and rituximab (anti-CD20 monoclonal antibody).
PMCID: PMC4140057  PMID: 25161355
Thalassemia major; auto immune hemolytic anemia; alloimmunization
9.  Red cell alloimmunization and autoantibodies in Egyptian transfusion-dependent thalassaemia patients 
The objective of this study was to explore the frequency of red cell alloantibodies and autoantibodies among β-thalassaemia patients who received regular transfusions.
Material and methods
This study included 501 patients with β-thalassaemia. This work planned to study the presence of alloantibodies and autoantibodies to different red cell antigens in multitransfused thalassaemia patients using the ID. Card micro typing system.
Of a total of 501 β-thalassaemia patients included in the study, 11.3% of patients developed alloantibodies; 9.7% of these alloantibodies were clinically significant. The most common alloantibodies were anti-K, anti-E and anti-C. The rate of incidence of these alloantibodies was 3.9%, 3.3% and 1.7% respectively. Autoantibodies occurred in 28.8% of the patients and 22.1% of these antibodies were typed IgG. There was a significant association between splenectomy with alloimmunization and autoantibody formation (p = 0.03, p = 0.001 respectively). There was no significant association between alloantibody, autoantibody formation and number of transfused packed red cells.
Alloimmunization to minor erythrocyte antigens and erythrocyte autoantibodies of variable clinical significance are frequent findings in transfused β-thalassaemia patients. There is an association between absence of the spleen and the presence of alloimmunization and autoantibody formation.
PMCID: PMC3284076  PMID: 22371805
β-thalassaemia; alloimmunization; autoantibodies
10.  Incidence of Red Cell Alloantibody among the Transfusion Recipients of Universiti Kebangsaan Malaysia Medical Centre 
Red blood cell alloimmunization is a common complication among the transfusion recipients. In Malaysia, multiple ethnicity causes genetic heterogeneity among the population which in turn can cause a wide variation of antibody. The objective of this study was to analyse the red cell alloantibody detected during the pre-transfusion testing. This was a cross-sectional study done in the blood bank of Universiti Kebangsaan Malaysia Medical Centre during the period of January–December 2010. The data was retrieved from the hospital laboratory information system. A total of 24,263 patients’ blood samples were subjected for pre-transfusion testing. Antibody screening was done using an indirect antiglobulin test method. The positive samples were further identified for antibody specificity. Antibody screening tests were positive in 184 patients out of 24,263 samples with the incidence of 0.76 %. Autoantibodies and alloantibodies were detected in 39/184 (21.2 %) and 140/184 (76.1 %) of the patients respectively. In five patients (2.7 %) the antibody specificity remained undetermined. Total 161 alloantibodies were identified. The suspected Anti-Mia alloantibody was observed most frequently (49/161, 30.4 %) followed by anti-E (30/161, 18.6 %) and anti-D (22/161, 13.7 %). Anti-E and anti-c were the most common combination of multiple alloantibodies. In view of the high incidence of suspected Anti-Mia antibodies, more efforts are needed to look into the techniques for confirmation of the Anti-Mia antibodies. Besides that, we suggested that all multiply transfused patients should be phenotyped for the Rh system and to supply Rh phenotype specific blood in order to limit alloimmunization.
PMCID: PMC3636363  PMID: 24426338
Red cell antibody; Alloimmunization; Transfusion recipient; Antibody specificity
11.  Antibody screening & identification in the general patient population at a tertiary care hospital in New Delhi, India 
Background & objectives:
The development of alloantibodies can significantly complicate transfusion therapy and results in difficulties in cross-matching of blood. Most literature on alloimmunization is limited to multitransfused individuals, with very few studies on the general hospital patients. This study was aimed at assessing the frequency and type of unexpected red cell antibodies in the general patient population at a multispecialty tertiary care centre in New Delhi, India.
The results of 49,077 antibody screening tests carried out on patients, from January 2009 to December 2012 were analyzed. The clinical and transfusion records were reviewed. The data were compiled and statistically analysed.
A total of 49,077 (29,917; 60.96% males and 19,160; 39.04% females) patient samples were screened for the presence of unexpected antibodies. Antibody screening was positive in 403 patients (0.82%). In the serum samples of 164 patients only autoantibodies were identified, 27 revealed autoantibodies with one or more underlying alloantibodies, while 212 patients had only alloantibody/ies in their serum. The overall alloimmunization rate was 0.49 per cent. Antibodies against the Rh system were the most frequent (64.1%), the most common alloantibody identified being anti E (37.2%), followed by anti D (19.2%).
Interpretation & conclusions:
Since clinically significant antibodies are frequently detected in our patient population, antibody screening and if required, identification is the need of the hour. Since antibodies against the common Rh and Kell blood group antigens are the most frequent, provision of Rh and Kell matched red cells may be of protective value.
PMCID: PMC4248387  PMID: 25366208
Alloimmunization; autoantibodies; general patient population; multitransfused; unexpected red cell antibodies
12.  Occurrence of anti-D alloantibodies among pregnant women in Kasese District, Western Uganda 
Journal of Blood Medicine  2015;6:125-129.
This study was undertaken to determine the distribution of ABO/RhD (rhesus D antigen) blood phenotypes, prevalence of anti-D alloantibodies, and the risk factors for alloimmunization among pregnant women in Kasese District, Western Uganda.
Materials and methods
Ethylenediamine tetraacetic acid-containing plasma samples and serum samples were taken from pregnant women attending the antenatal clinic. The blood groups were identified using the microplate grouping method, while the presence of anti-D alloantibodies was detected by the indirect antiglobulin test (IAT). Data were also collected from the pregnant women on the risk factors associated with anti-D alloantibody formation.
Among the 726 participants, the blood group distribution was as follows: O: 356 (49.%); A: 190 (26.%); B: 152 (21%); and AB: 28 (4%). A total of 28 (3.86%) pregnant women were RhD negative. Anti-D alloantibodies were detected in 88 (12.1%) of the participants; and of these, 13 (14.8%) were RhD negative. Statistically significant risk factors for anti-D alloimmunization included miscarriage, stillbirth, and postpartum hemorrhage.
Blood group O was the most common among the pregnant women in this study and the prevalence of Rh negativity was 3.8%. The frequency of anti-D alloimmunization among pregnant women in Kasese District was 12.12%, with 85.5% of these being RhD positive. Risk factors such as a history of stillbirths, miscarriages, and incidence of postpartum hemorrhage were significantly associated with anti-D alloimmunization. There is a need to routinely carry out antenatal blood grouping and IAT screening on pregnant women in Uganda to detect anti-D alloimmunization. Given the high prevalence of anti-D alloantibody formation among RhD-positive women, we recommend additional research studies on the role of autoimmunity among antigen-positive women, as well as the occurrence of RhD variants plus their implications on hemolytic disease of the fetus and newborn, in Uganda.
Video abstract
PMCID: PMC4408911  PMID: 25945071
ABO/RhD; blood groups; anti-D alloimmunization; indirect antiglobulin test; pregnant women; Western Uganda
13.  The Influence of Clinical and Biological Factors on Transfusion-Associated Non-ABO Antigen Alloimmunization: Responders, Hyper-Responders, and Non-Responders 
In the context of transfusion medicine, alloimmunization most often refers to the development of antibodies to non-ABO red blood cell (RBC) antigens following pregnancy, transfusion, or transplantation. The development of RBC alloantibodies can have important clinical consequences, particularly in patients who require chronic transfusions. It has been suggested that alloimmunization is more common in some clinical circumstances and patient populations than in others. As such, individuals that develop alloantibodies are frequently referred to as ‘responders’ in the medical literature. In contrast, individuals that do not develop alloantibodies despite repeated exposures to non-self blood group antigens have been referred to as ‘non-responders'. The purpose of this article is to review the phenomenon of RBC alloimmunization in the context of responders and non-responders to: i) establish a basic framework for alloimmunization as reported across several diverse patient populations; ii) more fully explore literature reports which support the concept of responders/non-responders regarding blood group antigen alloimmunization; iii) summarize the mechanisms that have been shown to predispose an individual to alloimmunization to determine how these factors may differentiate ‘responders’ from ‘non-responders'; and iv) briefly discuss some practical approaches to prevent alloimmunization in patients who may be prone to alloantibody development.
PMCID: PMC4280450  PMID: 25670929
Alloimmunization; Responders; Blood group antigens; Immunohematology
14.  Immune regulation in chronically transfused allo-antibody responder and nonresponder patients with sickle cell disease and β-thalassemia major 
American journal of hematology  2011;86(12):1001-1006.
Red blood cell alloimmunization is a major complication of transfusion therapy. Host immune markers that can predict antibody responders remain poorly described. As regulatory T cells (Tregs) play a role in alloimmunization in mouse models, we analyzed the Treg compartment of a cohort of chronically transfused patients with sickle cell disease (SCD, n = 22) and β-thalassemia major (n = 8) with and without alloantibodies. We found reduced Treg activity in alloantibody responders compared with nonresponders as seen in mice. Higher circulating anti-inflammatory IL-10 levels and lower IFN-γ levels were detected in non-alloimmunized SCD patients. Stimulated sorted CD4+ cells from half of the alloimmunized patients had increased frequency of IL-4 expression compared with nonresponders, indicating a skewed T helper (Th) 2 humoral immune response in a subgroup of antibody responders. All patients had increased Th17 responses, suggesting an underlying inflammatory state. Although small, our study indicates an altered immunoregulatory state in alloantibody responders which may help future identification of potential molecular risk factors for alloimmunization.
PMCID: PMC3618679  PMID: 21953592
15.  Evaluation of Alloimmunization Rate and Necessity of Blood Type and Screening Test among Patients Candidate for Elective Surgery 
Alloimmunization is a reaction of the immune system to foreign antigens. For prevention of alloantibody formation, performing of type and screen test is necessary on a patient’s blood specimen as part of pre-transfusion testing.
Materials and method
In this cross-sectional study, type and screen test done for 1420 patients with elective surgery for detection of alloantibody in Imam Khomeini hospital in Ardabil.
Prevalence of alloantibody in this population was 0.92% (13 patients) and 99.2% (1407 patients) showed no alloantibody in their serum. The most prevalent alloantibody was anti-K, anti-E and anti-c. No significant relationship observed between sex and alloimmunization rate.
Performance of type and screen test play an important role in reducing the rate of alloimmunization, and also, could reduce the demands for blood reservation in hospital blood banks.
PMCID: PMC3913156  PMID: 24505544
Alloimmunization; Type and screen test; Elective surgery
16.  Prevalence and Specificity of RBC Alloantibodies in Indian Patients Attending a Tertiary Care Hospital 
Advances in Hematology  2014;2014:749218.
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.
PMCID: PMC4216689  PMID: 25386192
17.  HLA Alloimmunization Is Associated With RBC Antibodies in Multiply Transfused Patients With Sickle Cell Disease 
Pediatric blood & cancer  2010;54(4):552-558.
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.
A cross-sectional study of HLA alloimmunization in SCD patients aged 3–21 years with a history of ≥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®).
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.
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.
PMCID: PMC3722881  PMID: 19890898
alloimmunization; human leukocyte antigen (HLA); sickle cell disease; transfusion
18.  Hemolytic disease of fetus and newborn due to maternal red blood cell alloantibodies in the Malay population 
Maternal red blood cell (RBC) alloimmunization may lead to production of harmful antibodies that result in hemolytic disease of fetus and newborn (HDFN). There is insufficient data on the prevalence of HDFN due to RBC alloantibodies in the Malay neonatal population.
The aim of this study was to determine the incidence of HDFN in the Malay neonatal population due to clinically significant RBC alloantibodies.
Subjects and Methods:
A cross sectional study was conducted in Transfusion Medicine Unit, Hospital Universitiy Sains Malaysia over one year period from January to December 2009. A total of 5163 Malay pregnant women who attended labor room for delivery were collected and analyzed prospectively. The blood samples were subjected to the standard immunohematological procedure for RBC antibody screening and identification using reagents of Diamed-ID Gel microtyping system. All the newborns with RBC alloantibody were investigated for the evidence of HDFN.
Thirty (0.58%) women were found to have clinically significant RBC alloantibodies. Most of the alloantibodies belonged to Rhesus (Rh) system (56.7%) where anti-E (33.3%) was the most common followed by anti-D (10.0%). Rh antibodies were the main cause of HDFN in fourteen (0.27%) neonates. Anti-D and anti-c were identified to cause moderate to very severe HDFN.
With the low prevalence of clinically significant RBC alloantibodies and HDFN, routine antenatal antibody screening practice may not be advised as a routine practice at present, preferably reserved for those women of RhD negative or with history of HDFN, significantly of those attributed to anti-c.
PMCID: PMC4140053  PMID: 25161351
Clinically significant alloantibodies; HDFN; Malay
19.  Prevalence, specificity and risk of red blood cell alloantibodies among hospitalised Hubei Han Chinese patients 
Blood Transfusion  2014;12(1):56-60.
The prevalence, specificity and risk of red blood cell alloantibodies vary widely among different geographic areas, races, and diseases and according to different methods of study, but no data are available on the Chinese Han population, who were investigated in the present study.
Materials and methods
Antibody screening was conducted among 42,517 hospitalised Hubei Han Chinese individuals using column agglutination technology. Samples that were positive in antibody screening were subjected to antibody identification by the tube test. Clinical data, including gender, age, race, transfusion history and records of alloantibody detection, transfusion reactions or haemolytic disease of the newborn, were collected to analyse the prevalence and specificity of alloantibodies and complications associated with them.
A total of 212 patients with alloantibodies were identified among 42,517 patients, yielding a prevalence of 0.50% in this study. Significantly different prevalence rates were observed according to age and sex. The most frequently identified alloantibodies were anti-E (87/212, 41.0%), anti-D (45/212, 21.2%), anti-M (41/212, 19.3%) and a combination of anti-E and anti-c (13/212, 6.1%). Haemolytic disease was observed in 13 infants with anti-D, three infants with anti-E and one infant with anti-Fya alloantibodies. Delayed haemolytic transfusion reactions occurred in four patients with alloantibodies.
In hospitalised Hubei Han Chinese individuals, the overall prevalence of alloantibodies was 0.50%, with anti-E, anti-D and anti-M being the most frequently identified alloantibodies. These results indicate that anti-D and anti-E alloantibodies were major risk factors for haemolytic disease of the newborn or delayed haemolytic transfusion reactions in this study population.
PMCID: PMC3926729  PMID: 24333071
RBC alloantibodies; antibody prevalence; antibody specificity; Han Chinese
20.  Transfusion of murine RBCs expressing the human KEL glycoprotein induces clinically significant alloantibodies 
Transfusion  2013;54(1):179-189.
Red blood cell (RBC) alloantibodies to non-self antigens may develop following transfusion or pregnancy, leading to morbidity and mortality in the form of hemolytic transfusion reactions or hemolytic disease of the newborn. A better understanding of the mechanisms of RBC alloantibody induction, or strategies to mitigate the consequences of such antibodies, may ultimately improve transfusion safety. However, such studies are inherently difficult in humans.
Study Design and Methods
We recently generated transgenic mice with RBC specific expression of the human KEL glycoprotein, with the KEL2 or KEL1 antigens. Herein, we investigate recipient alloimmune responses to transfused RBCs in this system.
Transfusion of RBCs from KEL2 donors into wild type recipients (lacking the human KEL protein but expressing the murine KEL orthologue) resulted in dose dependent anti-KEL glycoprotein IgM and IgG antibody responses, enhanced by recipient inflammation with poly (I:C). Boostable responses were evident upon repeat transfusion, with morbid appearing alloimmunized recipients experiencing rapid clearance of transfused KEL2 but not control RBCs. Although KEL1 RBCs were also immunogenic following transfusion into wild type recipients, transfusion of KEL1 RBCs into KEL2 recipients or vice versa failed to lead to detectable anti-KEL1 or anti-KEL2 responses.
This murine model, with reproducible and clinically significant KEL glycoprotein alloantibody responses, provides a platform for future mechanistic studies of RBC alloantibody induction and consequences. Long term translational goals of these studies include improving transfusion safety for at risk patients.
PMCID: PMC3732531  PMID: 23621760
21.  Risk Factors for Alloimmunisation after red blood Cell Transfusions (R-FACT): a case cohort study 
BMJ Open  2012;2(3):e001150.
Individuals exposed to red blood cell alloantigens through transfusion, pregnancy or transplantation may produce antibodies against the alloantigens. Alloantibodies can pose serious clinical problems such as delayed haemolytic reactions and logistic problems, for example, to obtain timely and properly matched transfusion blood for patients in which new alloantibodies are detected.
The authors hypothesise that the particular clinical conditions (eg, used medication, concomitant infection, cellular immunity) during which transfusions are given may contribute to the risk of immunisation. The aim of this research was to examine the association between clinical, environmental and genetic characteristics of the recipient of erythrocyte transfusions and the risk against erythrocyte alloimmunisation during that transfusion episode.
Methods and analysis Study design
Incident case–cohort study.
Secondary care, nationwide study (within the Netherlands) including seven hospitals, from January 2005 to December 2011.
Study population
Consecutive red cell transfused patients at the study centres.
The study cohort comprises of consecutive red blood cell transfused patients at the study centre.
Patients with transfusions before the study period and/or pre-existing alloantibodies.Cases defined as first time alloantibody formers; Controls defined as transfused individuals matched (on number of transfusions) to cases and have not formed an alloantibody.
Statistical analysis
Logistic regression models will be used to assess the association between the risk to develop antibodies and potential risk factors, adjusted for other risk factors.
Ethics and dissemination
Approval at each local ethics regulatory committee will be obtained. Data will be coded for privacy reasons. Patients will be sent a letter and an information brochure explaining the purpose of the study. A consent form in presence of the study coordinator will be signed before the blood taking commences. Investigators will submit progress summary of the study to study sponsor regularly. Investigators will notify the accredited ethics board of the end of the study within a period of 8 weeks.
Article summary
Article focus
Identifying transfusion-related risk factors of alloimmunisation against red blood cell (RBC) antigens.
Identifying clinical risk factors of alloimmunisation against RBC antigens.
Identifying environmental and genetic risk factors of alloimmunisation against RBC antigens.
Key messages
Alloimmunisation against RBC transfusion is a clinically relevant problem faced by transfusion specialists.
Identifying a high-risk group of responders who form allantibodies against transfused RBCs would be the next step towards transfusion of complete phenotyped matched RBC.
In synergy with other ongoing studies, cost-effectiveness of a phenotyped matched RBC approach will be assessed.
Strengths and limitations of this study
Multicentre, matched case–cohort design.
Good representative sample of controls from large base cohort of general population.
Cases and controls matched on the number of RBC transfusions.
Possibility that patients entering cohort have had transfusions prior to start of study period in other hospitals/non-study centres.
Previous pregnancies in women could play a role in alloimmunisation. Retrospective data will not allow for a comprehensive check on previous pregnancies.
There could be a few cases selected who are booster/secondary alloimmune responders, instead of first time ever alloantibody formers.
PMCID: PMC3358625  PMID: 22561355
22.  Alloimmunization to transfused HOD RBCs is not increased in mice with sickle cell disease 
Transfusion  2011;52(2):231-240.
Increased rates of RBC alloimmunization in patients with sickle cell disease may be due to transfusion frequency, genetic predisposition, or immune dysregulation. To test the hypothesis that sickle cell pathophysiology influences RBC alloimmunization, we utilized two transgenic mouse models of sickle cell disease.
Study Design and Methods
Transgenic sickle mice, which express human α and βS globin, were transfused with fresh or 14-day stored RBCs containing the HOD (hen egg lysozyme, ovalbumin, and human Duffyb) antigen; some recipients were inflamed with poly (I:C) prior to transfusion. Anti-HOD alloantibody responses were subsequently measured by ELISA and flow crossmatch; a cohort of recipients had post-transfusion serum cytokines measured by bead array.
Both Berkeley and Townes homozygous (SS) and heterozygous (AS) mice had similar rates and magnitude of anti-HOD RBC alloimmunization following fresh HOD RBC transfusion compared with control animals; under no tested condition did homozygous SS recipients make higher levels of alloantibodies than control animals. Unexpectedly, homozygous SS recipients had blunted cytokine responses and lower levels of anti-HOD alloantibodies following transfusion of 14-day stored RBCs, compared with control animals.
In sum, homozygous βS expression and the ensuing disease state are not alone sufficient to enhance RBC alloimmunization to transfused HOD RBCs in 2 distinct humanized murine models of sickle cell disease under the conditions examined. These data suggest other factors may contribute to the high rates of RBC alloimmunization observed in humans with sickle cell disease.
PMCID: PMC3218203  PMID: 21790627
red blood cells (sickle cell disease); alloimmunization; transfusion medicine
23.  Frequency and Specificity of Red Blood Cell Alloimmunization in Chilean Transfused Patients 
Alloimmunization is an adverse effect of blood transfusions. In Chile, alloimmunization frequency is not established, and for this reason the aim of this study was to investigate the prevalence and specificity of red blood cell (RBC) alloantibodies in Chilean transfused subjects.
Records from 4,716 multi-transfused patients were analyzed. In these patients, antibody screening was carried out prior to cross-matching with a commercially available two-cell panel by the microcolum gel test, and samples with a positive screen were analyzed for the specificity of the alloantibody with a 16-cell identification panel.
The incidence of RBC alloimmunization in transfused patients was 1.02% (48/4,716) with a higher prevalence in women (40/48). We detected 52 antibodies, the most frequent specificities identified were anti-E (30.8%), anti-K (26.9%), anti-D (7.7%), and anti-Fya (5.8%). The highest incidence of alloantibodies was observed in cancer and gastroenterology patients.
The data demonstrated a low alloimmunization frequency in Chilean transfused patients, principally associated with antibodies anti-E, anti-K, anti-D, and anti-Fya.
PMCID: PMC4404896  PMID: 25960709
Alloimmunization; Unexpected antibodies; Red blood cell transfusion
24.  Frequency of RBC Alloantibodies in Chinese Surgical Patients 
The aim of this study was to evaluate the frequency of red blood cell (RBC) alloantibodies in surgical patients.
Blood samples of 18,980 Chinese surgical patients were collected and tested between January 2009 and September 2010. For patients with RBC alloantibodies, sequences of antibodies were identified with the DiaMed Asia antibody screening system. Data regarding sex, age, transfusion history, pregnancy history, and alloantibody specificity were collected.
39 alloantibodies were identified from 18,980 samples, yielding a prevalence of 0.21%. The most frequently identified alloantibodies were Rhesus system antibodies (28/39, 71.8%), including anti-E (17/39; 1 anti-E accompanied by anti-Fyb), anti-c (5/39), anti-cE (2/39), anti-Cw (1/39), anti-D (1/39), and anti-e (1/39). Other antibodies included anti-M (5/39), anti-Lea (2/39), anti-Leb (1/39), anti-K+S (1/39), anti-JKa (1/39), and anti-JSa (1/39). The frequency of alloantibodies was greater in females than in males (31 vs. 8).
The results show a higher prevalence of RBC alloantibodies in females than in males. Anti-E was the most common alloantibody identified in this Chinese surgical population and was also more frequent in females compared to males.
PMCID: PMC3434327  PMID: 22969699
Red blood cells; Alloantibody; Surgery
25.  Alloantibodies and Australia antigen after open heart surgery 
Journal of Clinical Pathology  1974;27(1):45-49.
The development of irregular serum antibodies (alloantibodies) following massive transfusion was studied in 144 patients who had undergone cardiac valve replacement. An overall incidence of alloimmunization of 8·3% was found. Of the 15 antibodies detected nine were Rhesus anti-E and four anti-Kell. The incidence of anti-E formation in Rhesus E-negative patients was 11·4%; the corresponding figure for anti-Kell was 3·2%. The results suggest that the risk of allo-immunization is directly related to the volume of blood transfused, and Rhesus E-negative persons appear to be at particular risk.
Australia (Au) antigen investigations were also carried out in 102 of these cases. Three patients were Au antigen positive, one of them developing acute hepatitis. In each case no Au antigen could be detected in the donor blood that was used.
It is suggested that tests for alloantibodies and for the Australia antigen should become part of the routine follow-up of any patient receiving massive transfusion.
PMCID: PMC477984  PMID: 4206877

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