Surface expression levels of GARP on CD4⁺ T cells correlate positively with active TGF-β1 levels in the bone marrow of relapsing AML patients. (A) Kaplan-Meier analyses of overall survival rates of AML patients from the Gene Expression Profiling Interactive Analysis dataset according to GARP expression levels. High GARP expression (n = 87); low GARP expression (n = 86). Median value was used as the cutoff. P value was calculated by log-rank test. (B-C) Flow cytometry analysis indicating GARP expression on BMMCs isolated from AML patients with early relapse (red; n = 17) or without relapse (blue; n = 22). (D-E) Flow cytometry analysis showing GARP expression levels on CD4⁺ T cells (left) and platelets (right) from the bone marrow of AML patients with early relapse (red; n = 9) or without relapse (blue; n = 19). (F-G) Flow cytometry analysis showing GARP expression levels on NK cells (left) and CD8⁺ T cells (right) from the bone marrow of AML patients with early relapse (red; n = 9) or without relapse (blue; n = 19). (H-L) Spearman rank correlation analysis showing the relationship between active TGF-β1 levels and the proportion of GARP⁺ lymphocytes or the MFI corresponding to the density of GARP as shown by the Spearman correlation coefficients (r) and P values. The data in C, E, and G were analyzed by 2-tailed unpaired t-test; ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; ∗∗∗∗P < .0001. The data are represented as means ± standard deviation.