Persistent Antigen A after Minor ABO-Incompatible Hematopoietic Stem Cell Transplantation in Children: Two Case Reports

Abstract

Introduction: ABO blood type changes after ABOincompatible hematopoietic stem cell transplantation (HSCT). Most non-hematopoietic tissues retain the expression of the patient s own ABO antigens, which may adsorb from the plasma onto the donor s red blood cells (RBCs). Because of this phenomenon, a persistent patient s A and/or B antigen could be detected in the laboratory, despite 100% white cell donor chimerism. Adsorption of the patient s soluble ABO antigens on the newly formed RBCs complicates the interpretation of the patient s blood type and decision of transfusion therapy. Case Presentation: The first case report is a 6-year-old girl, A, D+, with T-cell acute lymphoblastic leukemia (ALL), transplanted with HLAmatched unrelated group O, D+ bone marrow. A second case report describes an 8-year-old girl, AB, D-, with ALL transplanted with an HLA-matched related group B, D+ bone marrow. The presence of persistent antigen A was registered in both patients more than 1 year after HSCT, despite complete donor chimerism. Conclusion: The weak expression of ABO antigens on RBCs after HSCT should be examined in detail for proper planning of transfusion therapies.