RESUMO
Fy3 is a high-prevalence red blood cell antigen of the Duffy (Fy) blood group system. Anti-Fy3 antibodies are rare and solely arise in individuals with a Duffy null phenotype (Fy(a-b-)), which is a phenotype that mainly occurs in people of African descent. Clinically, anti-Fy3 antibodies can cause both acute and delayed hemolytic transfusion reactions in adults as well as hemolytic disease in fetuses and newborns. Here, we report the case of a 26-year-old male with sickle cell disease (SCD) and a history of anti-E alloantibodies, who was admitted to the hospital with a vaso-occlusive crisis (VOC) and associated low hemoglobin (Hb) level. For the latter he received one unit of antigen-matched and crossmatch-compatible packed red blood cells (pRBCs) without complications. Ten days later the patient was readmitted with a further VOC and associated low Hb level, again requiring a red cell transfusion. However, no crossmatch-compatible pRBCs could be identified. Laboratory testing demonstrated pan-reactivity with additional reference testing demonstrating the presence of anti-E, anti-Fy3 and anti-Jkb alloantibodies. This case highlights the diagnostic and therapeutic challenges associated with blood transfusion in SCD patients with rare alloimmunization profiles.