BCG is taken up by bovine monocyte-derived DCs resulting in increased the expression of MHC class II, CD40 and CD80 and production of the Th1 polarising cytokine IL-12. Monocyte-derived DCs were cultured for 3 days and infected with FITC-labelled BCG (MOI 5) for 42 h. FACS plots from one representative animal (A) illustrate the percentage uptake of BCG-FITC by uninfected DCs (blue histogram) and BCG-infected DCs (pink histogram). Gates were set using uninfected DCs. Pooled data from four calves (A) illustrate the average percentage uptake of BCG-FITC ± SD by uninfected DCs (lighter bar) and BCG-infected DCs (darker bar). Uninfected and BCG-infected DCs were labelled with mAbs for MHC class II, CD40 and CD80 and analysed by flow cytometry. FACS plots from one representative animal show the expression of MHC class II (B), CD40 (C) and CD80 (D) by uninfected (blue histograms) and BCG-infected DCs (pink histograms). Positive cells were identified based on FMO controls (green histograms). Pooled data from four calves indicates the average MFI ± SD of MHC class II (B), CD40 (C) and CD80 (D) expression by uninfected (lighter bars) and BCG-infected DCs (darker bars). Supernatants were retrieved from uninfected and BCG-infected DCs and assayed for IL-12 production by ELISA. Pooled data from five calves represent the average levels ± SD of IL-12 BU/mL produced by uninfected (lighter bars) and BCG-infected DCs (darker bars) (E). Data were normally distributed (p > 0.05) and significance between uninfected and BCG-infected DCs was assessed using a 2-sample t test. p < 0.05*, p < 0.001***.