The population of IL-35-producing B cells was significantly expanded in GC patients. (A) Gating criteria from the peripheral blood for the live CD19+B cells and IL-35-producing B cells of GC patients are shown. (B) Representative data depicting IL-35-producing B cells in HCs and in patients with different stages of GC are shown with isotype. (C) The frequency of IL-35-producing B cells in patients with stage IV of GC (3.31 ± 0.24, n = 10) was obviously higher than the frequency in HCs (0.86 ± 0.05, n = 30, P < .0001), those with stage I disease (0.54 ± 0.09, n = 9, P < .0001), those with stage II disease (1.38 ± 0.08, n = 15, P < .0001), and those with stage III disease (2.22 ± 0.13, n = 16, P = .0002). The P-value was calculated by the Mann–Whitney U test. ∗∗∗P < .0001. GC = gastric cancer, HC = healthy control, IL-35 = Interleukin 35.