Immunohematologic tolerance of chronic transfusion exchanges with erythrocytapheresis in sickle cell disease.

BACKGROUND: Sickle cell disease (SCD) has become a major public health issue. Hydroxyurea and red blood cell (RBC) transfusion are the cornerstone treatments. Erythrocytapheresis (ECP) is an automated method for transfusion exchange. Given that ECP requires more blood than conventional transfusion, there is concern about alloimmunization and hemolytic transfusion reactions. We evaluate the incidence of hemolytic transfusion reactions and alloimmunization rates in patients receiving conventional blood transfusions and in patients participating in long-term blood exchange programs with ECP.

STUDY DESIGN AND METHODS: All hemolytic transfusion reactions and alloimmunizations in SCD patients were recorded over the period 2006 to 2011. Conventional transfusions and ECP were compared.

RESULTS: The cohort consisted of 188 SCD patients. The median (±SD) age was 23 (±14) years. The ECP and conventional transfusion groups comprised 49 and 139 patients, respectively. The prevalence of alloimmunization was 33% in the ECP group and 22% in the conventional transfusion group (p = 0.1797). The alloimmunization/RBC unit (RBCU) ratio was lower in the ECP group than in the conventional transfusion group (1.6 and 11.6 per 1000, respectively; p < 0.0001). Although patients in the ECP group received more than 10 times more RBCUs than patients in the conventional transfusion group (206 vs. 19 RBCUs per patient, respectively; p < 0.0001), none of the four recorded hemolytic transfusion reactions (n = 4) occurred.

CONCLUSION: Regarding alloimmunization, ECP exhibits a good immunohematologic safety profile relative to conventional transfusion in a large SCD mainly adult cohort.