Immunosuppressive effect of BRAF^V600Ein vivo. (A) Plasma from leukemic mice was collected at the point when each mouse exceeded 55% tumor cells in the peripheral blood CD45⁺ population and was evaluated by using a Milliplex cytokine assay (n = 18 for BRAF^WT and n = 21 for BRAF^VE). (B) T-cell immune parameters in AT mice were assessed by flow cytometry (n = 25 for BRAF^WT; n = 11 for BRAF^VE; P < .01 for each). (C) PD-L1 expression on CD11b⁺ cells (monocytes/macrophages) was assessed in peripheral blood from AT mice by flow cytometry (n = 25 for BRAF^WT; n = 11 for BRAF^VE; P < .001). (D) The percentage of F4/80⁺ cells (macrophages) was measured in the nonlymphocyte (CD5^–/CD19^–) population (n = 15 for each; P = .002). Horizontal lines indicate median. AT, adoptive transfer.