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Proteolytic enzyme preparations and techniques used routinely in blood group serology for the detection of atypical patient antibodies prior to transfusion vary widely and are often poorly standardised. Recent advances have been made in the use of biochemical methods to standardise and stabilise the potency of the enzyme preparations used. A joint working party of the International Council for Standardization in Haematology (ICSH) and the International Society of Blood Transfusion (ISBT) has investigated possibilities for the provision of standards for the protease preparations and techniques. The specification for these standards was that the performance of enzyme reference preparation in the reference technique should be of equivalent sensitivity to the ICSH/ISBT LISS spin indirect antiglobulin test using a titration series of a reference weak anti-D, and be free from false-positive reactions. The working party circulated materials for evaluation in inter-laboratory trials, followed by a laboratory workshop meeting to achieve agreement on the specification for reference materials and methods. Reference freeze-dried papain at 0.6 azoalbumin units and weak anti-D preparations (91/562) have been prepared and validated to meet these specifications. The performance of a test enzyme preparation in the technique for which it is recommended for use should be at least equal to that of the reference papain preparation, by the reference two-stage technique in terms of sensitivity, using a titration series of the reference anti-D, and freedom from false-positive reactions, using six fresh inert sera. The reference papain and weak anti-D can also be used to calibrate the level of proteolytic activity required in other procedures in blood group serology, such as new technology methods for antibody detection, and automated and microplate cell grouping procedures. These preparations and an agreed method for their use are now available from listed centres as ICSH/ISBT and Food and Drug Administration reference materials.

Background Rh discrepancies are a problem during routine testing because of partial and weak D phenotypes. Some blood units with weak and partial D expression may escape detection by serology. Limitations of serology can be overcome by molecular typing. The objective of study was to compare currently used serologic methods with molecular analysis to determine the potential application of molecular methods to improve D typing strategies and to estimate the frequency of weak D types among the Arab population. Study Design and Methods Fifty blood donor and patient samples with discrepant results of D phenotyping were subjected to routine serology to define the D phenotype including monoclonal anti- D immunoglobulin M and indirect antiglobulin test. Commercially available panels of monoclonal anti- D were used for identification of partial D and weak D phenotypes. Genomic DNA was evaluated using allele-specific amplification polymerase chain reaction with sequence-specific primers to define weak D type. Results Molecular typing confirmed most of the serology results; three samples that were not clear-cut serologically were identified by molecular typing, two samples as weak D Type 4.2 ( DAR), and one sample as weak D Type 4.0. Another two samples identified by serologic panel as weak D were unresolved by molecular typing. A sample with partial D Type II by serology revealed a Weak D Type 4.0 by molecular typing. Results interestingly showed the high frequency of weak D Type 4.2 ( DAR) in Egypt. Conclusion RHD molecular typing can solve discrepancies during routine testing due to partial and weak D phenotypes for better transfusion outcome. [ABSTRACT FROM AUTHOR]

The Transfusion Medicine Service (TMS) covers diverse clinical and laboratory-based services that must be delivered with accuracy, efficiency and reliability. TMS oversight is shared by multiple regulatory agencies that cover product manufacturing and validation standards geared toward patient safety. These demands present significant informatics challenges. Over the past few decades, TMS information systems have improved to better handle blood product manufacturing, inventory, delivery, tracking and documentation. Audit trails and access to electronic databases have greatly facilitated product traceability and biovigilance efforts. Modern blood bank computing has enabled novel applications such as the electronic crossmatch, kiosk-based blood product delivery systems, and self-administered computerized blood donor interview and eligibility determination. With increasing use of barcoding technology, there has been a marked improvement in patient and specimen identification. Moreover, the emergence of national and international labeling standards such as ISBT 128 have facilitated the availability, movement and tracking of blood products across national and international boundaries. TMS has only recently begun to leverage the electronic medical record to address quality issues in transfusion practice and promote standardized documentation within institutions. With improved technology, future growth is expected in blood bank automation and product labeling with applications such as radio frequency identification devices. This article reviews several of these key informatics issues relevant to the contemporary practice of TMS. [ABSTRACT FROM AUTHOR]

Background and Objectives Large-scale genotyping of blood donors for red blood cell and platelet antigens has been predicted to replace phenotyping assays in the screening of compatible blood components for alloimmunized patients. Although several genotyping platforms have been described, novel procedures and processes are needed to perform genotyping efficiently and to maximize its benefits for blood banks. Materials and Methods Here we describe the processes and procedures developed to introduce large-scale genotyping in our routine operations. Results Preliminary cost–benefit analysis indicated that genotyping must target frequent blood donors (> 3 donations/year) to be efficiently used. A custom-designed computer application was developed to manage the whole project. It selects frequent donors among recent donations, prints coded labels to identify blood samples sent to the external genotyping laboratory, and stores genotyping results. It can search for donors compatible for any combination of the 22 genotyped antigens as well as consult the current inventory for the presence of the corresponding blood components. The phenotype of recovered components is confirmed by standard serology techniques prior to shipment to hospitals. Conclusion Since October 2007, 10 555 blood donors have been genotyped. The database is used on a regular basis to find compatible blood components with a genotype–phenotype concordance of 99·6%. [ABSTRACT FROM AUTHOR]

Lessons from more than 100 years of immunohematology exemplify that many critical discoveries were made serendipitously and their more rapid implementation could have benefited transfusion recipients and pregnancies. Constituents of blood that are not essential for the attempted therapeutic benefit of a transfusion are largely removed from today's blood products. We are now moving on to avoid unnecessary exposure to potentially harmful constituents of the therapeutically required cells, like blood group antigens that are foreign to the patient. Cost efficacy needs to be kept in mind but may eventually prove much better than anticipated, once hidden benefits are captured, as we show by examples from past immunohematologic developments. Here, we detail clinical applications for molecular immunohematology advances including “dry-matching” that will improve transfusion outcomes and argue for their widespread implementation by rapid timelines through standards of practice. [ABSTRACT FROM AUTHOR]

BACKGROUND: Erythrocyte-magnetized technology (EMT) is a new fully automated method for ABO-RH-K phenotyping and antibody detection. The magnetization of red cells avoids centrifugation and washing phases. This report describes the results of an evaluation of this new technology on its specific automated system. STUDY DESIGN AND METHODS: ABO-RH-K phenotyping was compared between EMT and a semiautomated routine method (liquid microplate for ABO-D and microcolumn system for RH-K) on 311 patients' samples. The overall performance of the new method was further assessed in daily routine on a total of 11,022 samples during 3 months in two different laboratories. Antibody detection was evaluated on 624 consecutive patients' samples and on 118 frozen samples containing specific antibodies in comparison with commercial microcolumn systems. RESULTS: Eight of 311 ABO-RH-K tests (2.6%) were not interpreted by EMT. Seven of them were weak antigen or reverse grouping reactions showing a negative result with the routine method. On a 3-month follow-up, 216 of 11,022 tests (1.96%) were not interpreted by the system, 75 percent of them being due to weak or mixed-field reactions. EMT was better in detecting ABO-D mixed-field reaction than routine microplate method. Detection of clinically significant antibodies was similar between EMT and microcolumn. In contrast, EMT detected a markedly lower rate of presumed nonsignificant antibodies. The system presents an overall high reliability. CONCLUSION: EMT is tailored to meet the needs of the transfusion service and represents an important advance in the field of immunohematology. [ABSTRACT FROM AUTHOR]

Background and Objectives Enzymatic treatment of red blood cells is thought to reduce the cell zeta (ζ) potential, effectively decreasing the distance between cells to less than the length of an immunoglobulin G antibody binding site, and resulting in agglutination of cells. However, the ζ potential given by Smoluchowski's formula is based on theories of the electrophoresis of hard colloidal particles. A theory has recently been developed for the electrophoresis of colloidal particles covered with polyelectrolytes, which we call ‘soft particles’. Materials and Methods The electrophoretic mobility of red blood cell treated with papain and neuraminidase was measured as the electrolyte concentration of the medium using phosphate buffer. The results were analysed via the formula for ‘soft particles’. This mobility formula involved two parameters, the fixed charge density ( ZN) and parameter 1/λ characterizing the ‘softness’ of the cell surface layer. Results The best-fit curves of 0·1 units neuraminidase-treated red blood cells indicated that ZN decreased by 76% and 1/λ decreased by 8% compared to intact red blood cells. In contrast, in 5 units of papain-treated red blood cells ZN decreased by 45% and 1/λ decreased by 33% compared to intact red blood cells. Conclusion The present study shows that the change in ZN for neuraminidase-treated cells was very large, but the cells did not become agglutinable. Papain-treated cells had changes in both ZN and 1/λ, and the cells became agglutinable. 1/λ is one of the important factors for agglutination. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate a lyophilized intravenous immunoglobulin (IVIG) preparation containing anti-D (02/228; nominal reciprocal titre of 8) for its suitability to define the maximum limit of anti-D in IVIG products when used in a proposed reference method of direct haemagglutination of papain-treated erythrocytes, in an international collaborative study.Twenty laboratories tested 02/228 along with a negative control IVIG preparation and four IVIG samples containing different levels of anti-D. Nineteen laboratories performed direct haemagglutination methodology using papain-treated erythrocytes; five of these laboratories and one additional laboratory performed their in-house haemagglutination methodology (all indirect antiglobulin tests).The mode titre of 02/228, obtained by using the proposed reference method, was 8 (62·5% of tests). However, there was wide variation in haemagglutination titres between laboratories for three of the four samples. Correcting the titres of the samples relative to those of the proposed reference preparation reduced the interlaboratory variability and increased the frequency of the mode titres in three out of four samples. The indirect antiglobulin tests also showed wide interlaboratory variability and were less sensitive than the direct method in four laboratories. Eleven of the 14 laboratories that expressed an opinion considered that the level of anti-D in 02/228 was appropriate to define a specified limit.Our results demonstrate the necessity of using a reference preparation to define the maximum level of anti-D in IVIG products and ensure sufficient sensitivity in haemagglutination testing methodology. On the basis of these results, members of the European Pharmacopoeia Expert Group 6B recommended revision of the appropriate monograph to include this new specification and test. The Food and Drug Administration in the USA intends to adopt the same maximal specification defined by the reference preparation and to recommend the same test for the safety of IVIG products. Preparations 02/228 and 02/226 were also established by the World Health Organization as International Reference Reagents to standardize haemagglutination testing for anti-D in normal IVIG products. [ABSTRACT FROM AUTHOR]