Effect of Donor/Recipient ABO Mismatch on Outcome of Allogenic Hematopoietic Stem Cell Transplantation in Children: Single-center Study

ABO blood group mismatch between donor and recipient is thought to be associated with several immunopharmacological complications but is not considered a major contraindication to allogeneic hematopoietic stem cell transplantation (HSCT). However, the impact of such a mismatch on overall survival, transplant-related mortality, graft-versus-host disease, and time to neutrophil and platelet engraftment seems to be conflicting. This retrospective cohort was carried out on children and adolescents who underwent allogenic HSCT between January 2016 and January 2023. ABO compatibility state was assessed and grouped into compatible, minor, major, and bidirectional incompatible groups. The effect of ABO compatibility on various transplantation outcomes was assessed. Forty-three children (25 males and 18 females) with different diagnoses were included. More than half of the patients had no ABO mismatch. Major ABO mismatch was found to be associated with a higher incidence of acute graft-versus-host-disease (aGVHD), whereas near significantly higher mortality was observed in the minor mismatch group. Otherwise, no association was found between ABO mismatch and platelet or neutrophil engraftment. ABO mismatch does not affect the overall survival or the posttransplant engraftment of patients undergoing allogeneic HSCT. aGVHD was observed to be the only factor affected by ABO compatibility.