Background: The impact of ABO incompatibility on the outcome of hematopoietic stem cell transplantation (HSCT) is still debated. We report the results of a prospective, single-center study evaluating the impact of ABO mismatch on the development of immediate and late immuno-hematological complications, and the efficacy of the protocol used at the "Sapienza" University (Rome, Italy) to manage ABO incompatibility in patients undergoing HSCT.
Materials and methods: From January 2013 to December 2016, we prospectively analyzed all patients undergoing HSCT. Graft manipulation or desensitization strategies were used according to ABO incompatibility, donor sex and donor transfusion history. Red blood cell and platelet transfusions were given based on immunohematological features.
Results: From January 2013 to December 2016, 104 consecutive patients underwent HSCT from a matched related donor (29.81%), matched unrelated donor (53.58%), cord blood (1.9%) or haploidentical donor (14.42%). Forty-nine patients (47%) were ABO-identical and 55 (53%) ABO-incompatible (23 major, 25 minor, 7 bidirectional). Donor engraftment, graft failure or other complications did not differ between ABO compatible or incompatible patients. ABO incompatibility did not show a significant impact on graft-versus-host disease, overall survival or disease-free survival. Factors associated with the need for prolonged red blood cell support were ABO incompatibility (p=0.0395), HLA disparity between donor and recipient (p=0.004) and the onset of hemorrhagic cystitis (p=0.015). In multivariate analysis HLA disparity was the only statistically significant condition (p=0.004).
Discussion: ABO incompatibility does not represent a barrier to allogeneic HSCT. It is, however, associated with prolonged transfusion requirements. Close immunohematological monitoring, as a shared standard procedure, allows appropriate transfusion support to be provided and limits post-HSCT immuno-hematological complications.