TNF and infection: In order to analyze cytokine production by PBMCs stimulated with the wild type, the mutant, and the complemented strains (MOI 10), the cell supernatants were harvested at 24 h and 120 h (120 h as the time point wherein the lysX mutant showed an elevated intracellular growth in monocytes [28]) after infection for quantification of the pro-inflammatory cytokines IL-1β, IL-12(p40) and TNF-α as well as the anti-inflammatory cytokine IL-10.