Modeling Long-Term Erythropoietic Recovery After Allogeneic Stem Cell Transplants in Pediatric Patients

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

Introduction

ABO blood type changes after ABO-incompatible 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 HLA-matched 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.

Modeling Influencing Factors in B-Cell Reconstitution After Hematopoietic Stem Cell Transplantation in Children

Reduced total and memory B-cell numbers in peripheral blood long term after hematopoietic stem cell transplantation (HSCT) are associated with an increased incidence of infections and immune complications. Using novel modelling strategies, baseline factors influencing B-cell reconstitution can be comprehensively studied. This study aims to investigate the numerical total and memory B-cell reconstitution in children and the association with baseline determinants 0.5-2 years after allogeneic HSCT. Eligible for inclusion were children transplanted in our center between 2004-2017 who received a first HSCT for malignant or non-malignant disorders. The continuous absolute counts of total and memory B-cells were evaluated as outcome measure. Exploratory analysis at one year was done to identify possible determinants. Linear mixed effect modelling was used to analyze the association of these determinants with total and memory B-cell reconstitution 0.5-2 years after HSCT. In a cohort of 223 evaluable patients analyzed at 1-year after HSCT donor age, stem cell source, donor type, recipient age and conditioning were identified as significant determinants for total and memory B-cell numbers. Multivariable analysis revealed that both donor and recipient age were inversely correlated with the size of total and memory B-cell reconstitution. In contrast, no correlation was found with stem cell source, donor type and conditioning. Making use of linear mixed modelling both stem cell donor and recipient age were identified as independent determinants of total and memory B-cell reconstitution 0.5-2 years after HSCT.