Longitudinal changes in the immunoregulatory landscape after allo-HSCT. (A) Thirty-seven patients with AML/MDS were included in the longitudinal cohort. PBMCs were collected at months 3, 6, and 12 after transplantation and analyzed by mass cytometry. Twenty healthy donors were also analyzed. (B) Unsupervised cell-clustering analysis by FlowSOM, with 18 relevant metaclusters. (C) Principal component analysis (using FlowSOM data) of all tested samples from patients at the indicated time points (M3, n = 34; M6, n = 31; M12, n = 33) and from healthy donors. (D) Highlight of cell clusters showing significant longitudinal variations between the indicated time points. (E-F) Frequencies among PBMCs of cell metaclusters decreasing (E) or increasing (F) over time. (G-H) Volcano plots showing changes between M3 and M6 (G) and between M6 and M12 (H) in immune parameters assessed by classic manual gating. Significant parameters with percentage change >15% are annotated (percentage of cell population refers to total CD45⁺ live cells or to a parent cell subset when indicated by “/subset”). P values by Wilcoxon signed-rank tests. *P < .05; **P < .01; ***P < .001.