Fig. 5

Tumor-derived exosomes trigger B cells to exhibit strong suppressive activity against CD8⁺ T cells via HMGB1. CD19⁺ B cells (2 × 10⁵ cells/well) were cultured with or without HMGB1 or TDEs (tumor-derived exosomes) in the presence or absence of an anti-HMGB1 antibody plus 2 μg/ml CpG ODN in 96-well plates. After 3 days, B cells were collected and cocultured with autologous CD8⁺ T cells labeled with 5,6-carboxyfluorescein (CFSE) in the presence of anti-CD3/CD28 mAb bead stimulation, and then CD8⁺ T cell proliferation (a-b)and TNF-α(c-d) and IFN-γ (e-f) production were analyzed by flow cytometry after 3 days. a, c and e One representative experiment of three is shown. b, d and f The data are represented as the mean ± s.e.m. of three independent experiments. *P < 0.05, **P < 0.01, *** P < 0.001