Fig. 1

Functional myeloma-reactive cells reside in the PD-1⁺ T cell subset. KaLwRij mice were inoculated with 2 × 10⁶ 5T33-GFP-OVA myeloma cells iv. Mice were euthanized 28 days later, and spleens harvested for analysis. a PD-1⁺ and PD-1⁻CD8⁺ T cells were analyzed for SIINFEKL pentamer-positive cells by flow cytometry. The far-left panel depicts a representative example, and the right panels depict percentages and absolute numbers of pentamer-positive CD8 T cells (6 individual mice per group). b IFN-γ ELISPOT assay results, where splenic PD-1⁺ and PD-1⁻ CD8⁺ T cells were sorted by flow cytometry and stimulated with wild-type 5T33 (5T33-WT), 5T33-WT plus 10 μg/ml anti-PD-L1 added directly to the assay wells (5T33-WT + anti-PD-L1), or 5T33 cells expressing CD80 (5T33-CD80). The graph is representative of 4 independent experiments. c The percentage of SIYRYYGL (SIY) pentamer-positive cells in the spleens of mice bearing C1498-SIY leukemia. The left panel depicts a representative example, and the right panel depicts the results of 11 individual mice per group. d IFN-γ ELISPOT results, where splenic PD-1⁺ and PD-1⁻ CD8⁺ T cells were sorted by flow cytometry and stimulated with C1498-SIY myeloma cells or C1498-SIY cells plus 10 μg/ml anti-PD-L1 in the assay wells. The graph is representative of 4 independent experiments. *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001 and ****p ≤ 0.0001