FIG 8.
Heat inactivation increases the immune-stimulatory activity of strain 33277. (A) HEK cells expressing TLR2 were stimulated with either live (L) or heat-inactivated (HK) strains 33277, 33.k.rA.rB TKO, and 381 (105 bacteria). Fold change in NF-κB activation from bacterial stimulations is shown relative to the unstimulated control. (B) Differentiated THP-1 cells were stimulated with either live (L) or heat-inactivated (HK) strains 33277, 33.k.rA.rB TKO, or 381 (105 bacteria). Fold change in IL-1β production from bacterial stimulations is shown relative to the unstimulated control. Data are presented as means ± SD from triplicate sample determinations and are representative of two independent experiments. Asterisks indicate statistical significance as determined by Student’s unpaired t test (**, P < 0.001; ***, P < 0.0001). ns, not statistically significant.