Complications of ABO- and Non-ABO-incompatible Stem Cell Transplantations

Abstract Hematopoietic stem cell transplantation (HSCT) is used as a potentially curative treatment for a variety of malignant and nonmalignant hematological and congenital diseases. Human leukocyte antigen matching is critical and plays a dominant role in allogeneic HSCT donor selection. In contrast to solid organ transplantation, crossing the donor-recipient ABO incompatibility barrier has been feasible effectively expanding available donor pool. Despite the general consensus of ABO incompatibility not being a prohibitive barrier and having lesser effect on the overall HSCT outcomes, immune and hematological complications frequently do arise. Appropriate therapeutic and supportive management of ABO as well as non-ABO blood group–incompatible HSCT recipients can become critical and challenging in the posttransplantation time period. Understanding immunologic bases of the blood group antigens and primarily antibody response characteristics interactions might better appreciate the underlying mechanism of the hemolytic complications, delayed engraftment even contribution to graft versus host disease, and transplant-related mortality. It can also aid in the early detection of hemolysis and proper therapeutic management during the transplantation process. As such, this chapter discusses the immune concepts related to blood group antigens and antibodies and the laboratory testing that can benefit in the early decisions needed while managing HSCT recipients.