Fig. 5.
Checkpoint inhibition uncovers a Th1 immune response against tumor. (A–D) Splenocytes and lymph nodes were pooled from 3 C57BL/6 mice per group bearing 5-day established i.c. GL261 tumors treated with either PBS/PBS; VSV-GFP + anti-PD1 antibody; VSV-HIF-2α, VSV-Sox-10, and VSV-c-Myc + IgG; or VSV-HIF-2α, VSV-Sox-10, and VSV-c-Myc + anti-PD1 antibody. Cells were plated at 1 × 106 cells per well and restimulated in vitro 3 times at 24-h intervals with 1 × 105 cells of freeze/thaw lysates of GL261 tumors recovered from mice bearing i.c. GL261 tumors (A and C) or with freeze/thaw lysates of in vitro cultured GL261 (B and D). Forty-eight hours later, supernatants were assayed for IFN-γ (A and B) or IL-17 (C and D) by ELISA. (E) Splenocytes and lymph nodes were also restimulated with the VSV–N protein derived epitope at 5 µg/mL, 3 times for 24 h. Forty-eight hours later, supernatants were assayed for IFN-γ. Each result is representative of 3 separate measurements. Error bars are expressed as SD.