Adoptively transferred PD-1+ T cells persist in vivo and retain effector function. From the experiments in Fig. 4, four mice that received PD-1+ T cells and eliminated myeloma received a re-challenge of 2 × 106 5T33 myeloma cells 120 days after the initial myeloma inoculation. Five days later, spleens and bone marrow were harvested for analysis. a The percentages of CD4+ and CD8+ T cells detected in spleens by flow cytometry. b The percentages of CD4+ and CD8+ T cells harvested from the spleen and bone marrow expressing the indicated activation markers, memory markers, and PD-1. c Flow cytometric histograms showing expression of the memory marker CD127 on CD8+ T cells harvested from spleen and BM. Data represents pooled T cells from one experiment. d CD8+ T cells isolated from spleen or bone marrow (BM) by immunomagnetic sorting were tested in IFN-γ ELISPOT assays upon stimulation with wild-type 5T33 myeloma (5T33-WT) or 5T33-WT plus 10 μg/ml anti-PD-L1 (added to the assay wells). The graph depicts representative results from 2 independent experiments.