Relevance of alloimmunization in haemolytic transfusion reaction in sickle cell disease.

Transfusion remains a key treatment in sickle cell disease. The occurrence of a delayed haemolytic transfusion reaction is not rare and is a life-threatening event. The main cause of delayed haemolytic transfusion reaction is production of alloantibodies against red blood cell antigens. The high rate of alloimmunization in sickle cell disease patients is mainly due to the differences of red blood groups between patients of African descent, and the frequently Caucasian donors. From an immuno-haematological point of view, delayed haemolytic transfusion reaction in sickle cell disease patients has specific features: classical antibodies known to be haemolytic can be encountered, but otherwise non significant antibodies, autoantibodies and antibodies related to partial and rare blood groups are also frequently found in individuals of African descent. In some cases, there are no detectable antibodies. As alloimmunization remains the main cause of delayed haemolytic transfusion reaction, it is extremely important to promote blood donation by individuals of African ancestry to make appropriate blood available.