Fig. 2: MP lymphocytes differentiate into the T-bet^high subset in the presence of DC1-derived IL-12.

(a and b) IL-12 p40 and p35 are essential for optimal MP differentiation. a The frequency (mean ± SD) of MP cells among CD4⁺ T lymphocytes obtained from WT, Il12b KO, and Il12a KO mice is shown (WT n = 8 mice; Il12b KO n = 8 mice; Il12a KO n = 7 mice). b The representative plots show T-bet and CXCR3 expression in MP CD4⁺ T cells from each group while the bar graph indicates the frequency (mean ± SD) of T-bet^highCXCR3⁺ fraction among the same CD4⁺ T cell population (WT n = 8 mice; Il12b KO n = 8 mice; Il12a KO n = 7 mice). Data are pooled from three independent experiments performed. (c) IL-23A p19 is dispensable for T-bet^high MP differentiation. The bar graph shows the frequency (mean ± SD) of T-bet^highCXCR3⁺ cells among MP cells from WT and Il23a KO mice (n = 5 mice). Data are representative of two independent experiments performed. (d and e) DC1 tonically produce IL-12B p40. The representative contour plots in (d) show p40 expression by the indicated DC subsets from WT animals while the histograms in (e) depict YFP levels expressed by the same DC subsets from p40-YFP reporter mice. The filled histograms show negative control staining using non-reporter mice. The bar graphs indicate the p40⁺ and YFP⁺ fractions (mean ± SD) among indicated cell populations (n = 5 mice). Data are representative of three independent experiments. (f and g) Activated DC1 produce tonic IL-12B p40. The representative plots in (f) depict p40 expression in MHCII^{very high}CD86^highCD40^high and MHCII^highCD86^lowCD40^lowCD8α⁺ DCs from WT mice while the histograms in (g) show YFP expression in the same DC subsets from p40-YFP reporter mice. The bar graphs in (f) and (g) show the p40⁺ and YFP⁺ fractions (mean ± SD), respectively, among indicated CD8α⁺ DC subpopulations (n = 3 mice). Data are representative of two independent experiments performed. (h and i) p40⁺ DC1 are localized in the splenic T-cell zone. Different cell types in spleen of p40-YFP reporter mice were analyzed by multicolor tissue imaging. B220: yellow; CD4: purple; CD8: red; CD11c: blue; YFP: green. Scale bars show (h) 150 μm and (i) 15 μm. Images are representative of four sections from two mice. A two-sided t-test was performed to assess statistical significance. Source data are provided as a Source Data file.