Relapse remain the leading cause of treatment failure after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with acute myeloid leukemia (AML), despite substantial advances in transplant strategies and supportive care. The dynamics of immune reconstitution (IR) critically determine post-transplant outcomes by shaping the balance between graft-versus-leukemia (GvL) effects, graft-versus-host disease (GvHD), infectious complications, and leukemic immune escape.
Importantly, IR is not limited to numerical recovery of immune cells but represents a multidimensional and temporally organized process encompassing quantitative, qualitative, and functional immune restoration. In this review, we provide an integrated clinical laboratory–oriented framework for immune monitoring (IM) after allo-HSCT, with a specific focus on relapse prediction and risk stratification in AML.
We discuss the sequential kinetics of innate and adaptive immune recovery, key cellular subsets influencing GvL efficacy, and the impact of transplant-related factors, immunosuppression, and viral reactivations on IR trajectories. Particular emphasis is placed on functional immune states, including T-cell exhaustion, anergy, and senescence, as measurable laboratory correlates of impaired immune surveillance and impending relapse.