Early high-resolution immune profiles are associated with survival, relapse and graft-versus-host-disease after allogeneic hematopoietic cell transplantation.

Allogeneic hematopoietic cell transplantation (allo-HCT) is a well-established treatment in several hematological malignancies, where post-transplant complications are largely immune-driven. Post-transplantation (post-HCT) immune status assessment is essential for clinical monitoring of patients. In this study, immune cell composition and function was evaluated in whole blood from 77 adult allo-HCT recipients taken day +28 post-transplantation. High-resolution immunophenotyping assessed innate and adaptive immune compartments, including activation and immune checkpoint markers, while cytokine release after stimulation with T cell or innate stimuli examined immune function. Improved survival was associated with increased immune cell counts of both innate and adaptive immune compartments, as well as elevated cytokine-release responses. Elevated myeloid and innate lymphoid subsets and innately stimulated cytokine release were also associated with lower relapse incidence. Increased CD4 T cell PD-1 expression and HLA-DR on CD8 T cells was associated with poorer overall survival. These findings emphasize the importance of early innate immune reconstitution, indicating that integrating functional and phenotypic profiling could reveal new information regarding cell subsets of interest for allo-HCT patient monitoring, as well as potential targets for immunomodulation or cell therapies.