FIG. 5.

F. tularensis LVS ΔpyrF, but not Schu S4 ΔpyrF, stimulates primary macrophages to produce the proinflammatory cytokine TNF-α. Data are depicted as mean ± SEM levels of TNF-α and IL-1β secretion by primary human macrophages following a 24-h culture with the indicated strains (MOI, 10). Each panel represents a combination of three individual experiments using cells from separate blood donors. For panel B, LVS and LVS ΔpyrF were included in a single experiment for comparison. Uninfected control wells contained macrophages with no bacteria added (media). For TNF-α in panel A, P was <0.05 for LVS versus LVS ΔpyrF; for TNF-α in panel B, P was >0.05 for Schu S4 versus Schu S4 ΔpyrF.