Immune cell reconstitution after allogeneic hematopoietic stem cell transplantation in children with β-thalassemia major.

BACKGROUND: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only curative treatment for β-thalassemia major (TM). Currently, TM patients undergoing allo-HSCT achieve a survival rate exceeding 90%, with over 80% attaining disease-free survival following treatment at transplant centers worldwide. Sibling donors constitute the most common graft source, and the immune status of pediatric recipients directly influences transplant approach selection, conditioning regimen design, and prognosis. Children with TM exhibit distinct immune states before and after transplantation, yet research on post-transplant immune reconstitution in these patients remains limited. Therefore, this study aims to explore the characteristics of immune reconstitution following allo-HSCT in TM patients, with the goal of providing additional valuable insights for clinical management. This study aimed to investigate the differences in lymphocyte subset reconstitution within 1 year after allo-HSCT in children with TM, evaluate the efficacy of transplantation, and explore factors influencing post-transplant immune cell reconstitution.

METHODS: We retrospectively analyzed the clinical data of 74 children with TM who underwent allo-HSCT from September 2014 to December 2020 at the Transplantation Center of the Department of Hematology and Oncology, Children's Hospital of Chongqing Medical University to investigate the factors influencing the reconstitution of immune cells after transplantation in children with TM.

RESULTS: (I) The results showed that post-transplant cytomegalovirus (CMV) infection, CD34+ cell content in the graft, and donor type could influence the level of immune cell reconstitution after transplantation in children with TM. (II) The level of post-transplant cell reconstitution was higher in children who did not have anemic heart disease before transplantation, who were compatible human leukocyte antigen (HLA) 10/10 transplants, who were donor-recipient blood group compatibility, and who did not have acute graft-versus-host disease (aGVHD) after transplantation. (III) CMV-infection-positive and Epstein-Barr virus (EBV)-infection-positive children had higher levels of T-cell reconstitution, and CMV-infection-negative children had higher levels of NK-cell and B-cell reconstitution.

CONCLUSIONS: (I) Post-transplant CMV infection, CD34+ cell content in the graft, and donor type were independent influences on the level of T- and B-cell reconstitution after transplantation in children with TM. (II) No anemic heart disease before transplantation, donor-recipient blood type compatibility, no aGVHD after transplantation, no cGVHD after transplantation, and HLA 10/10 compatible transplantation are favorable for immune cell reconstitution after transplantation. (III) CMV infection and EBV infection after transplantation favored T-cell reconstitution, while CMV infection was detrimental to B-cell reconstitution.