IL-12 or activin A and TGFβ are involved in inducing IL-21 or CXCL13 production, respectively. Purified cDC2s and macrophages were co-cultured with naive CD4⁺ T cells in the presence of blocking antibodies, in combination or individually, against IL-12 (two different clones termed Ab1 and Ab2), activin A, and TGFβ1.2.3, or isotype control at the same total concentration. T cells polarized with cDC2 or CD14⁺ macrophages are termed T_cDC2 and T_MACRO, respectively. (A, B, D, and E) IFN-γ and IL-21 production was analyzed by intracellular staining after restimulation with PMA and ionomycin in presence of brefeldin A. (C, F, and G) CXCL13 secretion was analyzed by ELISA after restimulation with anti-CD3/CD28 beads. Each symbol represents an individual donor. (A–C) n = 11 for cDC2s and n = 10 for macrophages. (D and E) For cDC2: n = 10 for anti–IL-12 Ab1, n = 7 for anti–IL-12 Ab2, n = 9 for anti–activin A, and n = 8 for anti-TGFβ. For macrophages: n = 6 for anti–IL-12 Ab1, n = 7 for anti–IL-12 Ab2, n = 8 for anti–activin A, and n = 8 for anti-TGFβ. (F) For cDC2: n = 12 for anti–IL-12, n = 10 for anti–activin A, and n = 9 for anti-TGFβ. For macrophages: n = 7 for anti–IL-12, n = 10 for anti–activin A, and n = 8 for anti-TGFβ. (G) n = 7 for cDC2, n = 8 for macrophages. *, P < 0.05; **, P < 0.01; Wilcoxon test.