WT or TLR2−/− BMMs were infected with WT or ∆tolC Schu S4, or left uninfected, and release of the pro-inflammatory cytokine IL-6 into the culture medium was determined by ELISA at 24 h p.i. As previously observed (23), the Schu S4 ∆tolC mutant elicited elevated release of IL-6 (Fig. 4D) compared to infection with WT Schu S4 or uninfected controls. Here, TLR2 is linked to infection.