Antibody Identification Panel Research Articles

Using Soluble CD38 to Overcome Daratumumab Interference in Pretransfusion Compatibility Testing

Background: CD38 is a protein highly expressed on myeloma (MM) cells that has been shown to be an effective target antigen for monoclonal antibody therapies, so treatment with anti-CD38 monoclonal antibodies is a first line therapy for patients with MM. Although CD38 is weaker expressed on erythocytes anti-CD38 binds to CD38 on reagent RBCs and cause panreactivity in vitro and subsequent false positive reactions in indirect antiglobulin tests (IAT), antibody detection (screening) tests, antibody identification panels, and anti-human globulin (AHG) crossmatches. These findings suggest that the soluble CD38 method could improve transfusion safety for patients receiving anti-CD38 therapy, particularly in urgent clinical settings This study aims to evaluate the effectiveness of a new soluble CD38-based method in mitigating Daratumumab interference during pretransfusion compatibility testing." Methods: We evaluated the Grifols sCD38 method in 20 patients and compared it with the DTT method Results: In our experience the sCD38 method reduced testing time from 150 to 50 minutes and demonstrated 100% efficacy, compared to 90% with DTT. The sCD38 effectively mitigated the interference caused by anti-CD38 antibodies in 10 (100% efficacy) of patient samples tested while DTT was successful in only 9/10 (90% efficacy); no interference was observed in patients presenting anti erythrocyte antibodies. Moreover, there was no negative influence on DTT sensitive blood group systems such as KEL upon sCD38 treatment. Conclusions: In our Laboratory, in the year 2023, we processed 129 patients treated with anti-CD38. Therefore the reduction from 150 to 50 minutes in the time needed to perform tests for mitigation of anti-CD38 interference appears to be relevant with a recovery of approximately 210 technical-hours per year. Another highly appreciated operational aspect was the possibility of treating the patient's plasma and perform tests using automatic instruments (Erytra Grifols) available in our laboratory. In the evaluation of this new method, we did not observe failures in the mitigation of anti-CD38 interference. Furthermore, the results obtained in the samples that presented allo or auto antibodies were not affected by the treatment with sCD38. In our experience Grifols sCD38 assay is straightforward and quick to perform ant it is superior to DTT treatment in the mitigation of anti-CD38 antibody interference in MM patients treated with Daratumumab.

Prevalence and specificity of clinically significant red blood cell alloantibodies among hospitalized patients attending a tertiary care center in the southern part of India: A retrospective observational study

Abstract: BACKGROUND: Alloimmunization due to red blood cell (RBC) transfusions may occur due to discrepancy between donor and recipient’s antigenic exposure on RBCs. A thorough literature search shows limited data pertaining to the rate of alloimmunization and specificity of alloantibodies in the general patient population. The main aim of our study is to find the prevalence of alloimmunization rate and specificity of RBC alloantibodies among the patients who were admitted under different clinical departments in a tertiary care hospital. MATERIALS AND METHODS: Our study was a retrospective observational study in which the patient data regarding their blood grouping status, alloimmunization status, and other relevant details were collected from the case records that were recorded between 2021 and 2022. Antibody screening of these patients was carried out using Bio-Rad ID DiaCell I, II, III Asia (Mia+), 3-cell panel with the lot number (45330.13.x). The specificity of these alloantibodies was identified using the 11-cell antibody identification panel Bio-Rad (ID-DiaPanel 11 × 4) which belongs to lot number (06171.47.x–06271.47.x). RESULTS: The overall prevalence of RBC alloimmunization in our study was found to be 1.3% (n = 137). The most prevalent alloantibody in our study was considered to be anti-D (30.65%), followed by anti-c (18.24%) and anti-Jkb (16.05%). Females had a more significant association with the development of alloantibodies than males with P = 0.001. Patients with a history of transfusion also had a significant association with alloantibody formation (P = 0.008). CONCLUSION: Since alloimmunization may result in drastic unforeseen responses in patients during transfusions, prior alloantibody screening may provide an additional safety layer in providing safe transfusions to patients. Hence, this study advocates the provision of antigen-matched RBC units for ABO, Rh, and Kell antigens.

Antibody of Undetermined Specificity - The Eyes Do Not See What the Mind Does Not Know: Are You Dealing with a Low Prevalence Red Blood Cell Antigens?

ABSTRACT For identification (ID) of irregular antibodies, a standard antibody identification (AI) panel consisting of 18 mandatory antigens expressed on reagent red blood cells is used. The phenotype for each antigen is listed on a red cell antigram provided with each lot of the ID panel. In addition, special type of low-incidence antigens that are clinically significant are separately mentioned on the left- or right-hand column or on the reverse of the antigram. These cases highlight the importance of diligent AI to ensure safe transfusions and prevent adverse transfusion reactions in patients. The ID of rare and low-incidence red cell alloantibodies is important in ensuring safe transfusions and preventing hemolytic disease of fetus and newborn. In routine practice, these types of antibodies are often categorized as having an undetermined specificity due to their rarity and low prevalence in the population. We describe two cases of successful ID of rare and low-incidence red cell alloantibodies, Anti-Colton-b (Co(b)) and Anti-Kpa. Type and screen and irregular AI were performed on Immucor NEO Iris® (SPRCA), for both the female patients. Autocontrol and direct agglutination test were performed by column agglutination technique method (BIO-RAD, Coombs Anti-Ig G cards) and were negative for both the patients. Analysis of respective antigrams was done to rule out or rule in irregular antibodies. Initially, the reaction pattern indicated the presence of anti-Co(b) and anti-Kpa. However, the reaction only occurred in one cell out of the 14 cells tested for both patients. To ensure accuracy, the samples were rerun using different lots using the SPRCA methodology. To confirm the presence of anti-Co(b) antibodies, a selected panel cell was treated with an enzyme to enhance the expression of the Co(b+) antigen. Anti-Co(b) and anti-Kpa alloantibodies were successfully identified and AHG crossmatched; compatible and phenotype-matched blood units were reserved for the patients. Low prevalence antibodies are often missed during antibody screening due to lack of corresponding antigen-positive cells in cell panels or due to their weak reaction pattern and considering it for nonspecific reaction.

A patient with anti-f in India identified by extensive immunohematologic workup.

Anti-f is produced by exposure to the compound antigen ce (f) on red blood cells (RBCs), expressed when both c and e are present on the same protein (cis position). Although anti-f was discovered in 1953, there are few cases reported worldwide because the presence of anti-f is often masked by anti-c or anti-e and is not generally found as a single antibody. In the present case, anti-f was identified by using three-cell screening and 11-cell identification panels. The identification of anti-f was further supported by additional testing, including (1) Rh antigen typing; (2) antibody identification panels (enzyme-treated panel [ficin] and an in-house-constructed Rh panel); (3) look-back and phenotyping of donor RBC units, which were responsible for alloimmunization; and (4) molecular testing of the patient's RBCs.

Naturally Occurring Anti-D in a Male Blood Donor, Unresolved Mystery.

In accordance with numerous national and international criteria, screening donated blood for abnormal antibodies against red cell antigens is crucial for patient safety. Antibodies can be formed by three mechanisms: by immune responses, naturally occurring, or passively acquired. In accordance with departmental policy, ICT was performed on a 30-yearold male blood donor's sample in addition to ABO Rh grouping. He tested A Rh Dnegative and had a positive ICT (+ 2). Anti-D was identified by using the antibody screening and identification panel. Retesting revealed similar results, so we called the donor. We were unable to find a source for the Rh isoimmunization during the course of his history. On further work-up, we found that antibodies reacted only in the antiglobulin phase with no reaction in the saline phase, suggesting an IgG type of antibody. Also, the anti-D titers (IgG) of the donor were up to 1:32. All potential sources of Rh isoimmunization have been ruled out for a male donor. Therefore, we assume that this donor has naturally occurring anti-D, perhaps created by certain environmental factors, bacteria, or components of the COVID vaccine that have cross-reactivity with the D antigen. This instance emphasizes how crucial the ICT test on the donor blood is. In our case, all potential causes of alloimmunization were ruled out, leaving only exposure to antigens with antigenic similarity to D antigens as a viable explanation.

Identification of antibody specificity using adsorption-elution studies with incompatible packed red cell unit

Abstract Antibody identification is usually performed by antibody identification panels which are specially selected red cells, at least one of which has a homozygous expression for all clinically significant blood group antigens facilitating agglutination upon reaction with specific antibodies even exhibiting dosage. In general, adsorption elution is used in determining antibody specificities in the background of multiple alloantibodies with or without autoantibodies. Herein, we present a classic case where a routine antibody identification panel failed to detect a solo antibody from patient serum, following which we tested the eluate obtained after adsorption with a cross-match incompatible packed red blood cell unit using the same antibody identification panel, which unveiled the Fyb antibody.

OA1‐AM23‐TU‐13 | Defining the Utility and Frequency of Repeat Antibody Identification Panels in Previously Alloimmunized Patients

OA1‐AM23‐TU‐13 | Defining the Utility and Frequency of Repeat Antibody Identification Panels in Previously Alloimmunized Patients

Simulated RBC antibody identification training panels created using SARS-CoV-2 kodecytes and immune plasma.

BackgroundTraining is essential to develop and maintain skills required to be a competent serologist, yet samples required to achieve this are often difficult to obtain. We evaluated the feasibility of SARS‐CoV‐2 peptide modified RBCs (1144‐kodecytes) to develop simulated antibody screening and identification panels of reagent RBCs suitable for practical training, recognition, and grading of serologic reactions.Study Design and MethodsRBCs from a single donor were modified into kodecytes using Kode Technology function‐spacer‐lipid constructs bearing a short SARS‐CoV‐2 peptide. Kodecytes and unmodified cells were then arranged in patterns representative of RBC antibody profiles as simulated antibody screening and identification reagent cell panels (SASID), and then tested against immune donor plasma samples containing SARS‐CoV‐2 antibodies. Manual tube and two different gel card serologic platforms were evaluated by routine techniques. SASID exemplars were created for antibodies including D, Cw, f (ce), Jka (strong, weak, dosing), mixtures of D + E, Jka + K, Fya + E, high and low frequency antibodies and a warm IgG autoantibody.ResultsKodecytes (positive reactions) and unmodified cells (negative) when arranged and tested in appropriate patterns in SASID panels were able to mimic IgG antibody reactions, and were capable of measuring both accuracy and precision in reaction grading.ConclusionsKodecytes can be used to rapidly create in‐house simulated yet realistic antibody screening and identification panels suitable for large scale training in the recognition and grading of serologic reactions.

Occurrence of Erythrocyte Alloimmunization in Women Attending Antenatal Care Clinic

Background and Objectives: There is limited literature available on the alloimmunization rates among pregnant women in India. Our primary aim was to estimate the occurrence of irregular erythrocyte alloantibody (IEA) immunization amongst women attending our antenatal care (ANC) clinic and to guide our obstetricians for improved ANC as well as their fetal outcomes. Methods: A cross-sectional study was performed at the blood center in North India over 12 months. We recruited a total of 212 study participants. Antibody screening and identification were performed by using semi-automated column agglutination technology and commercially available 3-red cell antibody screen panel with reagent cards having anti-human globulin (AHG) (Ortho Clinical Diagnostics Inc., USA) and 11-red cell antibody identification panel with reagent cards having AHG (Resolve Panel A; Ortho Clinical Diagnostics Inc., USA) respectively. Once identified, the semi-quantitative doubling dilutions, i.e., serial titrations of the respective IEA were performed by the conventional tube technique to assess their potency. The association of various antibodies identified was analyzed using the Pearson's Chi-square test. Results: Of the 7248 pregnant women attending our ANC clinics, the antibody screening was requested for 212 cases. Out of these, 10.8% (n = 23/212) of women were positive and were sensitized both by active and passive immunization. Their average age (in years) was 27.6 ± 3.52 (20 to 34). The majority belonged to the Dehradun district of Uttarakhand. ABO system-wise, the most common type amongst the included subjects was A as recorded in 34.4%, followed by B (30.18%), O (24.12%) and AB (11.3%), respectively. Rh system-wise, nearly 47% (n=100/212) of subjects had Rh (D) negative blood group. Interestingly, amongst these 23 ANC cases with positive IAT, nearly 13% had a history of having received a blood transfusion. Conclusion: To sum up, the screening of majority of ANC in our hospital is restricted to Rh (D) negative pregnancies. Perhaps, more awareness among obstetricians regarding the universal screening of all ANC cases irrespective of their Rh (D) status is the need of the hour.

A new strategy for systematically classifying HLA alleles into serological specificities.

HLA serological specificities were defined by the reactivity of HLA molecules with sets of sera and monoclonal antibodies. Many recently identified alleles defined by molecular typing lack their serotype assignment. We surveyed the literature describing the correlation of the reactivity of serologic reagents with AA residues. 20 - 25 AA residues determining epitopes (DEP) that correlated with 82 WHOserologic specificities were identified for HLA class I loci. Thirteen DEP each located in the beta-1 domains that correlated with 24 WHOserologic specificities were identified for HLA-DRB1 and -DQB1 loci. The designation of possible HLA-DPB1, -DQA1, -DPA1, and additional serological specificities that result from epitopes defined by residues located at both -DQA1 and -DQB1 subunits were also examined. HATS software was developed for automated serotype assignments to HLA alleles in one of the three hierarchical matching criteria: (1) all DEP (FULL); (2) selected DEP specific to each serological specificity (SEROTYPE); (3) one AA mismatch with one or more SEROTYPES (INCOMPLETE). Results were validated by evaluating the alleles whose serotypes do not correspond to the first field of the allele name listed in the HLA dictionary. Additional 85 and 21 DEP patterns that do not correspond to any WHO serologic specificities for common HLA class I and DRB1 alleles were identified, respectively. A comprehensive antibody identification panel would allow for accurate unacceptable antigen listing and compatibility predictions in solid organ transplantation. We propose that antibody-screening panels should include all serologic specificities identified in this study.

Warm autoimmune hemolytic anemia with anti-e specificity: A case report

Warm autoimmune hemolytic anemia is a rare condition characterized by warm autoantibody destruction of red blood cells. Antibody specificity cannot be determined in most cases and an apparent autoantibody specificity to a specific antigen is rarely seen. Here we present a case of a 43-year-old female patient presenting with acute small bowel obstruction and requiring an exploratory laparotomy. However, laboratory investigations showed evidence of intravascular hemolysis with normocytic normochromic anemia, reticulocytosis, elevated bilirubin and lactate dehydrogenase levels, and low haptoglobin level. Two units of packed red blood cells were requested. Blood bank investigations including antibody screening, antibody identification panel, direct coombs testing with polyspecific and monospecific anti-human globulin, extended rhesus phenotype, and confirmatory elution testing revealed an IgG autoantibody with anti-e specificity. No compatible units with Rh (e) - positive units were found. However, Rh (e) - negative units’ transfusion was associated with a risk of alloimmunization and a decision of two least incompatible units was taken. So, an anti-e IgG autoantibody was identified which is a rare and challenging clinical condition in terms of diagnosis and transfusion.

Antibody incidence and red blood cell transfusions in patients on daratumumab.

Daratumumab (Dara), an anti-CD38 monoclonal antibody for hematologic malignancies, interferes with routine blood bank testing, specifically affecting the antibody screen and identification panels. In 2016, the AABB recommended performing a baseline phenotype or genotype before a patient (Pt) begins taking anti-CD38 to avoid this interference and potential problems with transfusion. The objective of this study was to assess red blood cell (RBC) utilization and subsequent incidence of alloimmunization to the transfused RBCs in patients receiving Dara. We monitored 244 patients taking Dara to determine their red blood cell transfusions and incidence of clinically significant antibody formation before and following administration of Dara. Poisson generalized estimating equations with log link were used comparing the post-Dara incidence and prevalence to those prior, with significance defined as p < .05. From September 1, 2015 to December 22, 2018, 244 patients on Dara were identified, of which 145 patients (59.4%) received a red blood cell transfusion. Antibody screens were performed on 97 of the 145 patients at least 2 weeks following RBC transfusion. Four of the total transfused patients (2.8% total, 4.1% patients with follow-up antibody screen testing) formed new clinically significant alloantibodies, which was not significantly different from Asare's hematologic incidence (p=.98/p=.49). This study showed our patients on Dara did not form alloantibodies following RBC transfusion at a higher incidence than similar patient populations.

Low prevalence red blood cell antigens: transfusions, babies, and changing demographics

See article on page 870–874, in this issue

Phenotype Frequencies of Major Blood Group Systems (Rh, Kell, Kidd, Duffy, MNS, P, Lewis, and Lutheran) Among Blood Donors in the Eastern Region of Saudi Arabia.

IntroductionThe understanding of blood group phenotypes in Saudi Arabia is limited to the ABO and Rh blood groups. Data for the other major blood group phenotypes in different populations have been widely studied and used as a reference for identifying antigen-negative blood in hospital blood banks. Such information is crucial for facilitating the challenging task of providing antigen-negative blood for patients with multiple antibodies.ObjectiveThe aim of this study was to determine the frequency of the major blood group phenotypes in the Eastern region of Saudi Arabia and compare them to phenotypes in other populations.MethodsA total of 100 volunteer Saudi donors were included in this study. Red blood cells from the donors were subjected to antigen typing of the major blood group systems (Rh, Kell, Kidd, Duffy, MNS, Lewis, Lutheran, and P) using the gel microtube technique.ResultsFrom the Rh blood group system, the e antigen was found in 97% of donors, followed by c at 86%. The Cellano (k) antigen of the Kell system was found in all donors, whereas the Kell (K) antigen was only found in 8 % of donors. The K+k- phenotype was not detected in our study. Unexpectedly, for the Duffy blood group system, the null phenotype Fy(a-b-) was found in 61% of donors. In the MNS blood group system, M+N-S+s+ was the most common phenotype at 24%.ConclusionThe frequency of blood group phenotypes in the Eastern region of Saudi Arabia differs from that in other populations because of the diverse ethnic backgrounds of those living in that region. The findings of this study can be used to establish a local donor registry to help provide antigen-negative blood for patients with unexpected antibodies or to create an in-house antibody identification panel to add to the commercial panel that would be useful for confirming antibody identification results.

Bombay and Lewis phenotype testing in correlation with leukocyte adhesion deficiency type II: The blood bank's role in diagnosis

Leukocyte adhesion deficiency type II (LAD II) is a rare hereditary disorder caused by the mutation in the guanosine diphosphate-fucose transporter gene (SLC35C1). LAD II is characterized by inexpression of ABO antigens (i.e., Bombay phenotype) and the lack of Lewis red blood cell (RBC) antigens. In addition to high neutrophil counts, patients also manifest recurrent infections with developmental delays and stunted growth. Blood bank laboratory tests such as blood grouping, RBC phenotyping, antibody screening and identification of the nature of the antibody were conducted in order to confirm the consequences associated with this gene anomaly in this case report. Type and screen results initially identified the patient as group “O” Rh positive with pan-reactive antibody screening cells and identification panel cells. The patient plasma showed significant incompatibility to all O-positive donors' RBCs. The patient's RBCs were tested against anti-H lectin and Lewis (Lea, Leb) typing antisera and showed no reaction, which meant that the patient does not express neither Lewis antigens nor H antigen on his red cell. The presence of anti-H (in a Bombay phenotype individual) explained the reactivity to reagent red cells and crossmatched incompatibility of Group O units as these cells naturally contained the H antigen.

The anti-Mia antibody – Report of four cases in a tertiary care hospital with review of literature

Anti – Mia antibody is antibody reacting with Mi III phenotype of the Miltenberger (Mi) subsystem. It is rarely reported in the West, however, it is common in Chinese and South East Asian populations. Very few cases have been reported in India. Here, we report 4 cases of the Anti - Mia antibody picked up on antibody screening of samples (which was performed using Asia ID-Diacell I-II-III Asia (Mia +) 3 cell panel). Patients: In all the four cases, ICT was positive. Antibody screening and Identification was done with 3 cell panel (ID-Diacell I-II-III (Asia)) and 11 cell panel (ID-DiaPanel) respectively. Antibody screening showed reaction in “Asia” cell (carrying Mia Antigen) of 3 cell panel. Antibody identification by 11 cell panel was negative ruling out antibodies of Rh, Kell, Duffy, Kidd, Lewis, P, Lutheran and MNS systems. Reaction with the “Asia” cell suggested the presence of Anti-Mia antibody which was confirmed by obtaining the same result when screening was repeated with 2 different lots of 3 cell panel. Discussion and Conclusion: The Miltenberger (Mi) subsystem comprises of a group of phenotypes of red cells that carry low frequency antigens associated with the MNSs blood group system. The Anti- Mia antibody was first described in 1951 in the serum of Mrs Miltenberger. Anti- Mia antibody is clinically significant and can cause Hemolytic disease of newborn (HDN) and mild to moderate haemolytic transfusion reactions (HTR). Most of the antibody screening and identification panels used in India are imported and represent the Western population. They do not have representation of the Mia antigen on their red cells. This leads to missing out of the Anti- Mia antibody which may cause HDN and HTR leading to significant consequences. Thus, the Mia antigen should be incorporated in our screening panels.

The First Comprehensive Study of H-Deficient Phenotypes in Iran

Summary Background: The lack of correct blood grouping practices can lead to missing of the rare Bombay Oh phenotype and subjecting patients to the risk of severe hemolytic transfusion reaction. In the absence of blood donor registry, transfusion management of patients is a challenge. We performed this study in order to estimate the prevalence of the Bombay blood group (Oh) in Iran and to determine whether consanguinity plays a role in the prevalence of Oh group. Methods: This is a descriptive study in the Immunohematology Reference Laboratory of the Iranian Blood Transfusion Organization (IBTO) Tehran, Iran, over a period of 7 years. All donor blood samples showing blood group O and a strong initial reaction with blood group O RBC control cells were tested with anti-H lectin. Also blood samples from blood group O patients were tested with anti-H lectin if all cells on both antibody screening tests and antibody identification panels were reactive with negative auto control test. Specialized tests like adsorption/elution technique and inhibition assay for determination of secretor status were performed on Oh cases. Any history of consanguineous marriages were recorded. All variables were categorical variables, and percentage and proportions were calculated manually. Results: Analysis of the results of over 7 million first-time blood donors in Iran showed that the most common ABO blood group was O, with 2,520,000 (36%) subjects. 56 Oh individuals' (donors and patients) phenotypes (0.0008%) were detected. Consanguinity was observed in 50 cases (89%). Conclusions: This study shows that the prevalence of Bombay blood group in the general population of Iran is relatively high (0.0008%) and associated with consanguineous marriage. Thus, consanguinity is still an important risk factor present.

Thirty‐three‐day storage of dithiothreitol‐treated red blood cells used to eliminate daratumumab interference in serological testing

Daratumumab binds CD38 on red blood cells causing interference with indirect antiglobulin tests. Dithiothreitol is used to eliminate interference allowing detection of alloantibodies. Haemolysis is observed during storage of dithiothreitol-treated antibody identification panel cells. The objective of this study was to develop a modified method for dithiothreitol treatment to reduce the haemolysis during 33days of storage and still be able to eliminate daratumumab interference. Panelcells were treated with various volumes of 0·2m dithiothreitol supplied by various manufacturers. Haemolysis Index of dithiothreitol-treated and untreated panel cells was measured and compared on days 1, 15 and 33. Antibody screening tests with dithiothreitol-treated screening cells were performed on samples from 15 daratumumab-treated patients (dose 16mg/kg) and 34 patients with known alloantibodies. Antibody identifications with dithiothreitol-treated panel cells were performed on seven additional known alloantibodies. Dithiothreitol treatment with a ratio of 30:25 (red blood cells:dithiothreitol) showed the same degree of haemolysis as with untreated panel cells. Daratumumab interference was eliminated in all 15 samples from daratumumab-treated patients. Twenty-six of 34 alloantibodies were detected, and all seven additional alloantibodies were identified using the modified dithiothreitol treatment. Eight alloantibodies within the Kell system were negative. No decrease in the reaction strength was observed during the 33-day storage period. The modified dithiothreitol method was able to reduce haemolysis during storage and to detect and identify alloantibodies in the presence of daratumumab.

Red Blood Cell Alloantibodies in Healthy Egyptian Blood Donors

Background: Alloantibodies are antibodies that are produced in response to foreign antigens, the main stimuli responsible for erythrocyte alloantibodies in healthy adult donors are previous pregnancies and transfusions. Red blood cell (RBC) alloantibodies, especially IgG class, are clinically significant because of the association with hemolytic disease of newborns (HDN), hemolytic transfusion reaction (HTR) and a significant reduction in lifespan of transfused red blood cells. It has been stated that hemolytic reactions due to erythrocyte alloantibodies in donor blood is a relatively rare occurrence; however, they can occasionally cause severe transfusion reaction, particularly if given to infants and in the setting of massive transfusion. Objective: We aimed in this study to screen healthy Egyptian blood donors for the presence of red blood cells alloantibodies in a trial to prevent complications of blood transfusion, other secondary possible outcomes are to reveal the differential frequency of these alloantibodies among donors with previous blood transfusion, multiple pregnancies, different age groups and gender. Subjects and Methods: This study was carried out on 200 healthy Egyptian blood donors coming to Ain Shams University Hospitals Blood Banks. Data was collected on: gender, age, frequent donor or first time to donate, history of previous blood transfusion, number of pregnancies (in female donors), history of hepatitis or other viral infection, history of diabetes mellitus, hypertension, and history of recent surgery. Results: Sera from donors was subjected to alloantibody screening by manufacturer’s antibody screening cells (Grifols I+II+III), when positive screening test, alloantibodies identification was done by manufacturer’s antibody identification panel (Grifols), which consists of 11 panels. Out of the 200 donors, alloantibodies were detected in 8 donors (4%), a percent which is higher than other studies, may be due to the smaller sample size, alloantibodies were: anti-Kell in 1 case (12.5%), anti-M in 1 case (12.5%), and anti-C in 1 case (12.5%), anti-c in 1 case (12.5%), and anti P in 1 case (12.5%), and 3 (37.5%) cases were non-specific antibodies, 130(65%) of donors were males and 70 (35%) were females with a male to female ratio 1.8:1, their ages ranged from 19 years to 65 years with median of 32 years. Conclusion: Relation between alloantibodies and gender, multipara, repeated blood transfusion and previous surgeries was done showing statistically significance of previous surgeries and presence of allo-antibodies

The Impact of Using Genotyped Reagent Red Blood Cells in Antibody Identification

Background: The detection and identification of antibodies to red blood cell (RBC) antigens is one of the most important and challenging issues in transfusion medicine. Up to date there are 354 RBC antigens recognized by the International Society of Blood Transfusion (ISBT). The reagent RBCs used in commercial antibody screening and identification panels however are usually serologically typed for up to 40 clinically important antigens. Thus the identification of many antibody specificities remains impossible when using reagent RBCs with only limited information about their antigens. To improve the pre-transfusion diagnostics, we developed antibody identification panels with reagent RBCs serologically typed for 26 antigens and additionally genotyped for 30 blood group alleles. Methods: The reagent RBCs in the panels were characterized serologically for the clinically most significant ‘standard' antigens. The reagent RBC donors were additionally genotyped by using in-house PCR-SSP methods. The antibody identification was performed in the indirect antiglobulin test using untreated and papain-treated RBCs in the gel technique. Antibodies identified due to the genotype information were confirmed by serology using appropriate reference RBCs. Results: Within a time period of 3 years and 8 months, 16,878 blood samples from 8,467 patients were tested in our reference laboratory. In total, 21 different antibodies from 10 different blood group systems could be identified in 126 patients (1.5%) due to the genotype information obtained for the reagent RBCs. Antibodies to antigens from the Knops system (53 patients; 42%, 8 patients with anti-Kn^b) and to Cartwright antigens (31 patients; 25%) were the most frequent. Conclusion: The use of genotyped reagent RBCs in antibody identification panels extends the range of detectable antibody specificities, accelerates the antibody identification, and improves the pre-transfusion diagnostics.