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Red blood cell allo-immunization is the immune response of an individual to foreign red blood cell antigens not present on the surface of their own cells. The aim of that paper is to clarify the different factors influencing the antibody response against red blood cell antigens., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)

Background: The use of blood group genotyping for the prediction of antigen expression has been discussed in clinical transfusion settings, but much less for reagent red blood cells selection. In France, the Centre National de Référence pour les Groupes Sanguins (CNRGS) produces a reference panel of reagent red blood cells, mainly used for red cell antibody identification. The use of high-throughput DNA analysis has never been applied to blood donors whose red blood cells are used as reagents. The aim of this study was to compare the serological phenotype and that predicted from DNA analysis in such donors, and to determine the benefit of DNA analysis in reagent red blood cells selection strategy., Study Design and Method: Red blood cells of 346 blood donors were typed with two different reagents for each antigen. The genotyping was performed by using HEA v1.2 BeadChips, BioArray Solutions, Immucor. The comparison between the serologically determined phenotype and that predicted from DNA analysis held on 8876 paired results obtained from 10 blood group systems and 25 antigens., Results: A 99.95% concordance was observed. Four cases of discrepancy for RH, KEL, LU and DO blood group systems were analyzed. Genotyping precisions were of special interest for the Duffy blood group system., Conclusion: Systematic DNA analysis brings important information on reagent red blood cells selection. It can be used at a routine level. Especially, the notion of "antigen of double dose" which is specified in several countries by government bodies should evolve regarding data obtained from DNA analysis. This should improve the quality of reagent red blood cells as first step for antibody identification., (Copyright 2010 Elsevier Masson SAS. All rights reserved.)

Since the discovery of blood groups in humans, several hundred new red blood cell antigens have been identified. Multiple terminology modes have been used to denote each new antigen identified, but without any consistent rules, nor international consensus. This was largely due to the many discoverers of these antigens, using either letters of the alphabet, numbers, part of the patient or donor's name, place of discovery or animal names. Besides, alternative terminologies for the Rh system were implemented in the middle of the twentieth century (Rosenfield, Fisher-Race, Wiener). The International Society of Blood Transfusion described for the first time in 1980 the advantages of an alphanumeric and homogeneous nomenclature, keeping with the genetic bases of blood groups, as well as a classification of all RBC antigens within several families. A variant of this new terminology, exclusively numerical, was simultaneously established, mainly designed for computer data exchange. Nearly 30 years later, 308 red blood cell antigens are described within 30 systems, 12 collections, one 700 series and one 901 series of blood groups. Any person involved in the field of immuno-haematology must master both the usual and international nomenclatures. The Wiener nomenclature used for Rh haplotypes, still largely used today, is also important to be known. The systematic use of the international nomenclature should be strongly encouraged, either in the labelling of blood products, clinical laboratory reports or blood type cards.

Aim of the Study: Determination of blood group antigens from data obtained by using molecular methods (genotyping) has become an indispensable tool in the specialized immunohematology laboratories. The French National Reference Centre for Blood group typing (CNRGS) routinely performs genotyping of the FY, JK and MNS system (common genotyping), providing a phenotype deduced from genotyping data for FY1, FY2, JK1, JK2, MNS3 and MNS4 antigens., Patients and Methods: We performed a study to evaluate the common genotyping prescriptions referred to the CNRGS over the last three years., Results: Between February 2006 and February 2009, the CNRGS performed 2392 genotyping, including 981 common genotyping. Analysis of 172 common genotyping performed in 2008 showed that 63.8% of the prescriptions expressed a genotyping demand. Of the latter, 42.7% were genotyping prescriptions only, whereas 57.2% were prescriptions of genotyping associated with alloantibody identification. All prescriptions refer to blood group genotyping indications issued from guidelines, with no incorrect prescription, that are patients transfused within four months before blood sampling in 63.6% of cases or a positive direct antiglobulin test in 24.5% of cases. Lastly, 36% of the blood samples referred to the CNRGS had no genotyping prescription. Yet, common genotyping was performed by the CNRGS to get complete immunohematology data for antibody identification., Conclusion: Usefulness of blood group genotyping in specialized immunohematology laboratories is obvious. However, the strategy for implementation of molecular methods remains to be defined. Use of high-throughput DNA analysis should change our way of working.

A rare blood group is usually defined as the absence of a high prevalence antigen or the absence of several antigens within a single blood group system, if its prevalence in France is 4/1000 or less in the general population. An individual with a rare blood phenotype can develop a naturally-occurring or immune antibody corresponding to his rare specificity. In case an extremely low stock of compatible blood is available at the national level, a so-called "transfusion deadlock" is described. Most of the individuals with a rare blood group are coincidently identified when a routine pretransfusion testing or pregnancy follow-up is performed, if the antibody(ies) corresponding to the rare specificity is(are) present. Other individuals are discovered following a systematic red cell typing, or family investigations in siblings. One hundred and twenty-one rare blood specificities and 42 rare blood genotypes are currently defined at the French National Reference Laboratory for Blood Groups (CNRGS-Paris). The French national registry of individuals with a rare blood phenotype/genotype includes about 9600 people, who are urged to regularly donate blood for the National Rare Blood Bank. This bank, based on a homologous blood transfusion program, is in charge of the long-term storage of rare frozen blood units, that can only be delivered after receiving authorization from the CNRGS. The global and individual care management of the individuals with a rare blood group, concerning potentially several hundred thousand people in France, requires a close cooperation between all the protagonists within the transfusion chain.