Figure 7. In vivo PD-L1 blockade increases ovarian tumor antigen (FR-α) specific inflammatory cytokine production by ID8 TILs.
(a) Representative data and summary showing percentage of IFN-γ production by CD8+ TILs from treated mice as indicated. Following treatment with GVAX or FVAX and/or in vivo αPD-L1 and α-4-1BB antibody treatment, the TILs were harvested and stimulated ex vivo with FR-α peptide for 5 h at 37°C in the presence of brefeldin-A. For intracellular staining, permeabilized cells were stained for IFN-γ or phosphorylated form of transcription factors (T-bet, eomes and S6 kinase). (b) A week after completion of treatment, 2 × 105 CD8+ T cells from 5–10 pooled tumor draining mediastinal lymph nodes were re-stimulated with 1 × 105 FR-α peptide pulsed DCs for 36–48 h. Cytokine (IFN-γ and TNF-α) production from culture supernatant was measured following in vitro culture using cytokine bead array (CBA) kit. (c) Flow cytometry analysis showing percentage of phosphorylated (p) T-bet, pEomes and pS6K expression by CD8+ TIL from treated mice. All analyses were performed using CD8+CD45+ TIL from treated mice. N.S. not significant.