Concordance of two polymerase chain reaction-based blood group genotyping platforms for patients with sickle cell disease.

CONCLUSIONS: In recent years, polymerase chain reaction-based genotyping platforms, which provide a predicted phenotype, have increased in both patient and high-throughput donor testing, especially in situations where serologic methods or reagents are limited. This study looks at the concordance rate between two platforms commercially available in the United States when used for testing samples from patients with sickle cell disease (SCD), a group particularly vulnerable to alloimmunization. DNA extracted from samples from 138 patients with SCD was tested by human erythrocyte antigen (HEA) BeadChip (Immucor, Norcross, GA) and by ID CORE XT (Progenika-Grifols, Barcelona, Spain). Predicted phenotype results were compared, and a concordance rate was calculated. Discrepancies were resolved by Sanger sequencing. All testing was done under an institutional review board-approved protocol. A concordance rate of 99.9 percent was obtained. Sanger sequencing was performed on four samples with discrepancies in the Rh blood group system. Three samples had a similar allelic variant detected by ID CORE XT. Two of the three discrepant samples were correctly identified as V+w, VS- by ID CORE XT but not by HEA BeadChip. The third sample, predicted to have a phenotype of V+, VS+ by sequencing, was called correctly by HEA BeadChip but not by ID CORE XT, which had predicted V+w, VS-. The fourth discrepancy was identified in a sample that ID CORE XT accurately identified as RHCE*ce[712G] and predicted a partial c phenotype. This result was confirmed by Sanger sequencing, whereas HEA BeadChip found no variants and predicted a c+ phenotype. The high concordance rate of the two methods, along with the known limitations of serology, warrant further discussion regarding the practice of serologic confirmation of extended phenotypes. Clinical significance of the identified discrepancies remains to be determined.

An update on the Duffy blood group system.

CONCLUSIONS: This update of the Duffy (FY) blood group system (Meny GM. The Duffy blood group system: a review. Immunohematology 2010;26:51-6) includes additional variants to the Duffy system (International Society of Blood Transfusion system 8; five anti-gens) identified through molecular studies. The most interesting clinical updates, however, include further evaluation of the roles of the Duffy glycoprotein, also known as the atypical chemokine receptor 1, in malaria and hematopoiesis. The transition to understanding the important role of blood group antigens in homeostasis and disease continues.

Recognizing and resolving ABO discrepancies.

CONCLUSIONS: Patient samples are routinely typed for ABO prior to transfusion. Determining the ABO group requires both red blood cell (RBC) antigen typing for A and B (forward type) and testing for anti-A and anti-B in the plasma (reverse type). An ABO discrepancy exists when the result of an ABO RBC typing, or forward type, does not agree with the result of the plasma typing, or reverse type. This brief review examines several causes of ABO discrepancies encountered in the clinical transfusion service. Options for resolving these discrepancies are presented, including a discussion of which discrepancies should be resolved using molecular testing. Finally, case studies illustrate transfusion options in patients with ABO discrepancies. Discrepancies can also be encountered when ABO typing is performed on samples from blood or tissue donors, although those discrepancies will not be discussed in this review.

The American Rare Donor Program.

The American Rare Donor Program (ARDP), headquartered in Philadelphia, Pennsylvania, maintains a comprehensive database of donors with "rare blood types." The ARDP secures blood and blood products for difficult-to-transfuse patients. Remarkably, a significant number of physicians, both in the United States and abroad, remain unaware of the unique and critical services that the ARDP provides to critical care specialists and their patients.

Polymorphisms in canine platelet glycoproteins identify potential platelet antigens.

Human alloimmune thrombocytopenic conditions caused by exposure to a platelet-specific alloantigen include neonatal alloimmune thrombocytopenia, posttransfusion purpura, and platelet transfusion refractoriness. More than 30 platelet-specific alloantigens have been defined in the human platelet antigen (HPA) system; however, there is no previous information on canine platelet-specific alloantigens. Using the HPA system as a model, we evaluated the canine ITGB3, ITGA2B, and GP1BB genes encoding GPIIIa (ß3), GPIIb (αIIb), and GPIbß, respectively, which account for 21 of 27 HPA, to determine whether amino acid polymorphisms are present in the orthologous canine genes. A secondary objective was to perform a pilot study to assess possible association between specific alleles of these proteins and a diagnosis of idiopathic thrombocytopenic purpura (ITP) in dogs. By using genomic DNA from dogs of various breeds with and without ITP, sequencing of PCR products encompassing all coding regions and exon-intron boundaries for these 3 genes revealed 4 single-nucleotide polymorphisms in ITGA2B resulting in amino acid polymorphisms in the canine genome, 3 previously reported and 1 newly identified (Gly[GGG]/Arg[AGG] at amino acid position 576 of ITGA2B. Of 16 possible ITGA2B protein alleles resulting from unique combinations of the 4 polymorphic amino acids, 5 different protein isoforms were present in homozygous dogs and explain all of the genotype combinations in heterozygous dogs. There was no amino acid polymorphism or protein isoform that was specific for a particular breed or for the diagnosis of ITP.

False-positive pregnancy test after passive transfusion of beta-human chorionic gonadotropin from donor red blood cells during erythrocytapheresis.

BACKGROUND: Patients transfused with blood products may passively receive soluble antibodies, proteins, and other analytes that persist during the collection, processing, and transfusion of the blood product. In this report, a female patient who received transfusion of five red blood cell (RBC) units during erythrocytapheresis later demonstrated an unexpected positive result in assays for the beta-subunit of human chorionic gonadotropin (bHCG), a screening test for pregnancy. The result caused postponement of an elective surgical procedure. A follow-up test 1 week later was negative. STUDY DESIGN AND METHODS: To investigate the possibility of passive transfusion of the hormone from a donor RBC unit, a sample from each of the units transfused was assayed for the level of bHCG. RESULTS: One of the 5 units transfused to the patient had a high level of bHCG. The observed bHCG level in the recipient was found to be comparable to the predicted level, given the donor's plasma bHCG level and accounting for the dilution factors in the preparation of the RBC unit and the erythrocytapheresis procedure and the in vivo t((1/2)) of the hormone. CONCLUSION: The donor, who was unaware of her pregnancy status at the time of donation, harbored a high bHCG level that caused the positive test result in the recipient patient's serum and urine. If an unexpected analyte or serology is detected in a recipient of a blood transfusion, it is important to consider the possibility of passive transfusion of the analyte.

The risk of posterior subcapsular cataracts in granulocyte donors.

BACKGROUND: Therapeutic use of adrenal corticosteroids is a risk factor for the development of posterior subcapsular cataract (PSC). Because corticosteroids are given to donors of apheresis granulocytes (PMNs) to improve yield, this study was performed to determine the prevalence of PSCs in PMN donors relative to a matched control group of apheresis platelet (PLT) donors. STUDY DESIGN AND METHODS: This study was a cross-sectional study stratified by age, sex, and lifetime apheresis experience at three sites. Individuals who had made at least five PMN donations preceded by corticosteroids were eligible. The presence of PSC was ascertained by grading digital retroillumination images of both lenses. A random subset of participants underwent clinical eye examinations by ophthalmologists masked as to study group. A logistic regression model was used to compute odds ratios (ORs). RESULTS: Granulocyte donors had given a mean of 13 donations (range, 5-39 donations) over a mean period of 8.5 years (range, 0.3-25.2 years). The mean corticosteroid exposure, in cortisol equivalents, was 2840 mg (range, 1067-9040 mg). Six of 89 PMN donors had photographic evidence of PSCs versus 4 of 89 controls. This difference was not significant (OR, 1.54; 95% confidence interval [CI], 0.46-5.08). Five of 33 PMN donors and 3 of 30 PLT donors had evidence of PSC by clinical examination. This difference was also not significant (OR, 1.61; 95% CI, 0.35-7.39). CONCLUSION: This study does not support the hypothesis that corticosteroid stimulation of PMN donors is associated with an increased risk of developing a PSC.