Immunophenotype of malignant CAR T cells. (A) UMAP plots comparing phenotype of the donor-derived CAR T-cell product and malignant CAR T cells: (left) combined plot showing CD3⁺CD4⁻CD8⁺ (cluster 1, red dots), CD3⁺CD4⁺CD8⁻ (cluster 2, green dots), and CD3⁻CD4⁺CD8⁻ (cluster 3, blue dots) cells; (middle) plot showing differences in CD4, CD8, and CD3 expression between malignant CAR T cells (aquamarine dots falling in cluster 2 and cluster 3) and the donor-derived product (red dots falling in cluster 1 and 2); and (right) expression of the CAR19 transcript of CD3⁺ and CD3⁻ cells (dot plot). (B) Expression of lineage markers on malignant cells including B cells, macrophages, monocytes, dendritic cells (DC), NK cells, and γ-δ T cells. (C) T-cell memory, (D) T-helper subtype, and (E) activation and inhibitory molecule expression of malignant T cells. CLR, centered log ratio.