Particularités immunohématologiques dans les populations africaines et antillaises. Implications transfusionnelles

Abstract

Polymorphism encountered within the immunogenic blood group antigens is responsible for allo-immunization after transfusion or pregnancy. Antigen frequency differs depending on the ethnic background. This is the case for the Afro-caribbean population. Three levels of differences can be identified: common antigens in the RH, FY, JK and MNS blood groups, high frequency antigens in the RH, KEL, FY and MNS blood groups and low frequency antigens in the RH and KEL blood groups. When donors are primarily European caucasian in ancestry, the ethnic polymorphism may affect donor service in term of supply and demand. The effects of differences in antigen frequency are especially important when long term transfusion support is needed such as in sickle cell disease. When a Black patient is immunized against an association of common antigens for the Caucasian population (ex: anti-RH2, anti-FY1, anti-JK2, anti-MNS3) or against a high frequency antigen always present in the Caucasian population (anti-MNS5), only rare blood from the same ethnic population kept frozen at the rare blood bank can be transfused to avoid immuno-haemolytic accidents.