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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.

Immunoglobulin preparations of anti-D (RH1) are injected to prevent haemolytic disease of the newborn. Such preparations are obtained by the fractionation of plasma from immunized donors. Measurement of the concentration of IgG anti-D is required to estimate the potency of anti-D preparations and sera from immunized donors. We have developed an ELISA method for the quantification of IgG anti-D. This method included the following steps, sensitization of red cells by anti-D, solubilization of red cell membranes by Triton, and eventually, measurement of IgG anti-D concentration by ELISA. The international reference preparation of anti-D (68/419) was used as a reference. With this method, we measured IgG anti-D concentrations in 5 immunoglobulin preparations of anti-D and in the sera of 10 donors immunized by D antigen. The ELISA results were compared with those obtained by automated hemagglutination. A mean anti-D concentration of 56.2 micrograms/mL was found by ELISA in immunoglobulin preparations. Similar results were obtained by automated hemagglutination (mean 52 micrograms/mL). In the sera of 10 D-immunized donors, anti-D IgG concentration varied from 2.2 to 59.8 micrograms/mL. A good correlation between ELISA and automated hemagglutination was observed in these sera (r = 0.98, p < 10(-7)). In conclusion, the ELISA technique offers an alternative to automated hemagglutination. It requires only the standard equipment necessary for immuno-enzymatic methods.

The sensitivity of the low ionic strength solution antiglobulin test (LISS-AGT), polyethylene glycol antiglobulin test (PEG-AGT), low ionic strength solution solid-phase antiglobulin test (LISS-SPAT), gel low ionic strength solution antiglobulin test (GEL-LISS), and gel papain test (GEL-PAP) was compared in titration studies of 460 sera containing identified IgG alloantibodies. The GEL-PAP was 100% sensitive to detect Rh antibodies, whereas the PEG-AGT was the most sensitive to detect Kell, Duffy, Kidd, Ss, and rare blood group antibodies. The better performance of PEG-AGT was especially obvious with Kell, Duffy, and Ss antibodies (S = 100%). When the sensitivity of the LISS-AGT, PEG-AGT, GEL-LISS, and GEL-PAP was evaluated in different routines, the GEL-LISS showed to be more sensitive than PEG-AGT in the detection of clinically significant antibodies. These discrepant results showed that the performance of a technique may change when it is applied as a routine.

Abstract: 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. [ABSTRACT FROM AUTHOR]