Prolonged Thrombocytopenia and Severe Transfusion Reaction after ABO-Incompatible Allogeneic Hematopoietic Stem Cell Transplantation in a Patient with Chronic Myelomonocytic Leukemia.

Introduction: Major ABO-incompatible allogeneic hematopoietic stem cell transplantation (allo-HCT) is a common practice and represents a challenging transfusion scenario. Prolonged thrombocytopenia with increased platelet transfusion needs is one of its reported adverse effects, and this has been linked to the persistence of recipient anti-donor isoagglutinins.

Case Presentation: A 55-year-old male patient, O Rh(D)-positive, with chronic myelomonocytic leukemia underwent major incompatible allo-HCT from a A Rh(D)-negative donor. He presented with prolonged thrombocytopenia and multiple transfusion reactions after A Rh(D)-negative platelet transfusions. Considering the outcomes of numerous examinations, we tested the anti-A1 titers, finding a significant persistence of anti-donor isoagglutinins. We limited platelet transfusions to blood group O Rh(D)-negative donors, which significantly decreased the requirement for platelet transfusions. In addition, the transfusion reactions ceased.

Conclusion: In case of transfusion reactions against platelet products in major ABO-incompatible allo-HCT patients, isoagglutinin monitoring should be considered and a change in the platelet transfusion protocol may be beneficial in patients presenting high isotiters against recipient's blood type.