Transcriptional characteristics of common features among heterogeneous patients with CTCL. (A) Side-by-side view of the integrated UMAP of CD4⁺ T cells from 11 patients with CTCL and 3 healthy controls, along with a heat map displaying the DEGs when all CTCLs cells were compared with all normal CD4⁺ T cells combined from patients and healthy controls (heat map: minimum percentage >0.25%, minimum difference in percentages >0.2; adjusted P ≤ .05, log fold change threshold = 0.25). (B) Pathway analysis of all DEGs revealed 15 enriched (adjusted P ≤ .05) pathways in the CTCLs. (C) Plots demonstrate increased expression of the central memory T-cell activation genes SELL, CCR7, ITGB1, BRD2, TNFRSF25, REL, TSPAN2, TNFRSF4, and NR4A2 and the T-cell exhaustion genes TIGIT, TOX, CTLA4, LAG3, and PDCD1 in CTCLs vs normal CD4⁺ T cells, as well as increased CD82, CCR4, and KIR3DL2 gene expression in CTCLs. (D) The percentage of CTCLs that proliferate in response to TCR engagement was significantly increased after a period of rest in vitro. Each line represents 1 patient-derived sample (n = 3). (E) Representative flow cytometric analysis of the proliferative capacity of CTCL cells. Cells were cultured with no stimulation for 4 days (No Stim) or were stimulated immediately after isolation (No Rest + Stim) or after a 4-day rest (Rest+Stim). Simulation consisted of anti-CD3+anti-CD28 for 2 days followed by washing and a 2-day expansion in the absence of stimuli. UMAP, Uniform Manifold Approximation and Projection.