Approach to red cell transfusions and stem cell transplant in an alloimmunized sickle cell patient with hyperhemolysis history.

BACKGROUND: Patients with sickle cell disease (SCD) are highly predisposed to alloimmunization and severe hemolytic reactions. Hyperhemolysis, a transfusion reaction that causes destruction of transfused and autologous red cells, may occur without new red cell antibody production or with antibodies not considered clinically significant in SCD. Avoidance of transfusions is the key preventative strategy; however, transfusions are unavoidable for SCD patients undergoing hematopoietic stem cell transplant [HSCT]). This case outlines our approach for safe transfusions in an SCD patient undergoing HSCT. CASE REPORT: A 15-year-old alloimmunized SCD patient experienced hyperhemolysis after red cell exchange, requiring immune suppressive therapy and a delay in planned HSCT. To ensure safe red blood cell (RBC) transfusions in the peri-transplant period, the patient's humoral immune response was suppressed via Rituximab before pre-transplant red cell exchange. Additionally, the patient and sibling donor had RHD haplotype mismatch with recipient anti-D, which could predispose to delayed red cell engraftment and prolonged posttransplant transfusion requirements. Hence, we used a plasma cell-depleting agent (Daratumumab) pre-transplant. Early and close collaboration with the transfusion laboratory, national immunohematology reference laboratory, and the rare blood program facilitated the timely availability of compatible units via extensive serologic testing, use of monocyte monolayer assay, and donor RBC genotyping. The patient underwent pre-transplant red cell exchange with no hemolytic reactions and had minimal post-transplant transfusion requirements. CONCLUSION: Safe transfusions in SCD patients with hyperhemolysis undergoing HSCT require timely collaboration between laboratory and clinical services, careful selection of matched RBC units for transfusion, extensive serologic testing, and suppression of humoral immune response.