Bone marrow environment immune dysfunction at posttransplantation relapse in pediatric patients with AML. (A) Single-cell bone marrow immune microenvironment of (B) CD8⁺ T cells, (C) CD4⁺ T cells, and (D) NK cells for UPN1-4 at diagnosis and posttransplantation relapse. (E) Top differentially expressed Hallmark pathways between diagnosis and posttransplantation relapse in T and NK cells. Scale from 0 to 100 is a combined enrichment score c = log(p) × z, in which c is the combined score, p is the P value computed using the Fisher exact test, and z is the z-score computed by assessing the deviation from the expected rank. DPT, double positive T cell; TGF, transforming growth factor; TNF, tumor necrosis factor; Treg, regulatory T cell.