Figure 2. Impact of propionate on the response of dendritic cells and splenocytes.

(A) BMDCs were pre-incubated for 1 h with increasing concentrations (0, 0.5, 1, 2 and 4 mM) of propionate before exposure for 8 h to LPS (10 ng/ml), Pam₃CSK₄ (10 ng/ml), E. coli (10⁶ CFU/ml) and S. aureus (10⁷ CFU/ml). TNF, IL-6 and IL-12p40 concentrations in cell culture supernatants were quantified by ELISA. Data are means ± SD of triplicate samples from one experiment performed with 4 mice and representative of 2 experiments. No cytokine was detected in the supernatants of unstimulated cells (P < 0.001 vs stimulus alone). (B) Mouse splenocytes were incubated for 48 h with or without propionate and E. coli or S. aureus (10⁶ CFU/ml). Proliferation was measured by ³H-thymidine incorporation. IFNγ concentrations in cell culture supernatants were quantified by ELISA. Data are means ± SD of triplicate samples from one experiment performed with 4 mice. *P < 0.05 vs stimulus without propionate.