John Libbey Eurotext

Hématologie

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Transfusion therapy in autoimmune hemolytic anemia Volume 15, issue 5, septembre-octobre 2009

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Authors
Institut national de la transfusion sanguine ; et Centre national de référence pour les groupes sanguins, Paris

Autoimmune hemolytic anemia (AIHA) is a quite rare hematological disorder. Its annual incidence is approximately 1 in 25’000. AIHA are characterized by autoantibodies recognizing antigens on the individual’s own red blood cells (RBCs), resulting in their increased destruction rate. Anemia occurs when the destruction rate of RBCs exceeds the regenerative capacity of the bone marrow. The clinical symptoms, including asthenia, pallor, icterus, are especially present when anemia is severe. AIHA classification is based on the properties of the pathogenic autoantibodies and presumptive etiology. Warm AIHA, cold AIHA, mixed AIHA, paroxysmal cold hemoglobinuria and drug-induced haemolytic anemia are described. Transfusion is the major available symptomatic treatment for AIHA, but this therapy demonstrates significant challenges as well as specific immunologic risks, which are important to be aware of. When the patient shows an autoantibody directed against a high prevalence antigen (> 99%), as is generally the case, it is not possible to find compatible RBC units in the blood bank. The autoantibody may also mask the presence of clinically significant alloantibodies. In order to ensure an optimal transfusion safety in those patients, it is necessary to perform additional investigations in the immunohematology laboratory, including adsorption of serum on autologous RBCs or allogeneic adsorptions, extended phenotyping and sometimes RBC genotyping. Those tests turn out to be time-consuming and labor-intensive, and may be reserved to reference laboratories. A close communication is mandatory between the clinicians and immunohematology laboratory staff, in order firstly to confirm the transfusion therapy indication and evaluate its risk-benefit ratio, and secondly to define whether the time required for additional laboratory procedures is consistent with urgency of the patient’s transfusion need.