Comparison of cytokine levels induced by purified LPS derived from the wild-type strain and its isogenic mutants in human Mono Mac 6 (MM-6) and murine macrophage RAW264.7 cells. (A to C) Mono Mac 6 cells were stimulated for 24 h with LPS of indicated strains at a concentration of 0.1 pmol/ml, and IL-6, IL-1β, and TNF-α levels in supernatants were quantified with the Bio-Plex assay. (A) IL-6 in the supernatants of Mono Mac 6 cells. (B) IL-1β in the supernatants of MM6 cells. (C) TNF-α in the supernatants of Mono Mac 6 cells. (D, E) RAW264.7 cells were stimulated for 24 h with LPS of indicated strains at concentrations of 0.1 pmol/ml and 10 pmol/ml, and TNF-α and GM-CSF levels in supernatants were quantified with the Bio-Plex assay. (D) TNF-α in the supernatants of RAW264.7 cells. (E) GM-CSF in the supernatants of RAW264.7 cells. The results of one experiment representative of two independent experiments are shown. Error bars indicate SEM of triplicates. ***, P < 0.001; **, P < 0.01; *, P < 0.05 compared with χ3761. †††, P < 0.001; ††, P < 0.01; †, P < 0.05 compared with χ8573. n.s., not significant.