Abstract

A rare erythrocyte phenotype is characterized by the absence of expression of a high-frequency antigen on red blood cells or the absence of several antigens within the same blood group. In France, a blood group is considered rare when the frequency in the general population is less than 1/4000. Allo-immunization against lacking antigens through transfusion or pregnancy requires providing adapted transfusion-support in order to secure further transfusions. A national file of individuals including both patients and donors has been implemented for more than 20 years, along with a national rare blood bank (BNSPR) designed to provide rare blood 24 hours a day. The organization is based on cooperation between the National Blood Service (EFS) and the National Reference Center for Blood Groups (CNRGS).

Rare blood donation is anonymous, homologous and non paid. Special dispensations are applied compared to the standard blood donation rules: age of donor, absence of leucodepletion, specific agreement for markers except HIV. The BNSPR is in charge of the rare blood unit management (reception, freezing, storage, thawing, distribution, delivering, and shipping) and of the sample storage. RBCs are freezed under −80°C with glycerol according to the Valeri’s method. The post wash storage period is limited to 24h in the open system of cryopreservation because the deglycerolization step is performed in an open system. In the automated closed system, RBCs can be both glycerolized and deglycerolized, and then the post wash storage in SAGM at +4°C is extended to 7 days. In both systems, the mean value of freeze-thaw wash process recovery is 79.5%. The mean percentage of haemolysis and residual extracellular glycerol, measured on the day of deglycerolization, are 0.2% and 0.15g respectively.

From 2002 to 2007, 4064 units were frozen, 1076 were thawed for 211 patients and 2426 were destroyed for storage regulation. The aim of regulation is to reach for almost all units the standard blood donation rules, but also to improve the phenotypic and genotypic characteristics of the units. As an example, in the FY blood group, only the RH:−20, KEL: −6 units will be maintained in the frozen stock in order to avoid allo-immunization against low frequency antigens, difficult to detect in a routine laboratory. At the end of 2007, 9600 individuals are listed in the national file, 5470 blood units corresponding to 1603 donors are frozen. 97% of the donors are typed at least in the RH, KEL, FY, JK and MNS. More than 125 rare specificities are represented with the following repartition of the units: FY: −1, −2 (25%), KEL: −2 (18%), YT: −1 (15%), rare RH (8%), Vel-negative (6.5%), MNS: −3, −4, −5 (6%) LU: −2 (5%). Units from Afro-Caribbean donors represent 35% of the stock. 83% of the units are stored for less than 10 years and 84% are tested for HIV and HCV NAT. 2% of the units present biological abnormality markers, 2% have medical counter-indications in the donors and 0.9 % are not leuco-depleted. The mean number of transfused units per patient is 5.8 (min=1, max=36 for a KEL: −2 individual). The mean number of transfusion episodes per patient is 2.5 (min=1, max=16 for a FY: −1, −2 individual).

Since 2002, the BNSPR has been helping other countries and 16 units have been shipped to different regions e.g. Canada, The Netherlands, Belgium, Germany, Switzerland. France should now define its policy regarding the shipping of rare blood units to foreign countries in order to extend this service to longer populations. This may be done in the cooperation frame of the European Council.

Disclosures: No relevant conflicts of interest to declare.

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