PD-1+ T cells expand ex vivo and provide anti-myeloma immunity when given as ACT. a Experimental design. At day 0, Rag-1-deficient recipient mice were inoculated with 106 5T33-GFP cells iv. Five days later, mice received ex vivo-expanded T cells as ACT. Some mice also received 125 μg anti-PD-L1 intraperitoneally (ip) at the indicated time points. Control mice received no treatment. b Survival curves of mice treated with ACT consisting of 3-4 × 106 PD-1+ T cells at a CD4:CD8 ratio of 1:1 with or without 125 μg anti-PD-L1. Moribund mice were euthanized. Data are combined from 2 independent experiments, with n = 6–7 mice per experimental group. c Survival curves of mice given the following: (1) No treatment, (2) 3-4 × 106 PD-1+ CD4+ and CD8+ T cells at a ratio of 1:1 [PD-1+ T cells group], (3) 3-4 × 106 PD-1− CD4+ and CD8+ T cells at a ratio of 1:1 [PD-1− T cells group], (4) 1.5-2 × 106 PD-1+ CD8+ T cells alone, or (5) 1.5-2 × 106 PD-1+ CD4+ T cells alone. All mice, except the ‘no treatment’ group, received 125 μg anti-PD-L1 ip on days 7, 10, 14 and 17 after myeloma inoculation. The data are combined from 3 to 4 independent experiments, with n = 11–15 mice per experimental group.