Fig. 5

Ablation of activin-A signaling in CD4⁺ T cells alters the profile and attenuates the effector function of lung tumor-infiltrating CD8⁺ T cells. A Representative flow cytometry plots (left) and cumulative MFI values of PD-1, LAG-3 or TIM-3 expression by CD3⁺CD8⁺ T cells infiltrating lung tumors of CD4/ALK4-KO or WT LLC-OVA-tumor bearing mice (right). B Representative flow cytometry plots (left) and cumulative percentages of IFN-γ-expressing cells among CD3⁺CD8⁺ T cells infiltrating lung tumors (right). C Representative flow cytometry plots (left) and cumulative MFI values of perforin and granzyme-B expression by CD3⁺CD8⁺ T cells infiltrating lung tumors (right). D LLC-OVA cells were co-cultured with lung tumor-infiltrating CD8⁺ T cells from CD4/ALK4-KO or WT LLC-OVA-tumor bearing mice. Representative flow cytometry plot (left) and cumulative percentages (right) depicting caspase-3 activity of LLC-OVA cells. E LLC-OVA cells were co-cultured (at indicated ratios) with lung tumor-infiltrating CD8⁺ T cells from CD4/ALK4-KO or WT LLC-OVA-tumor bearing mice. Cytotoxicity was assessed by LDH measurement in cell culture supernatants. Data are mean ± SEM and are representative of 6 (A-D) and 2 (E) independent experiments. Statistical significance was obtained by unpaired Student’s t-test; *P < 0.05 and **P < 0.01