FIGURE 1.

Cytosolic Listeria monocytogenes in macrophages induces IL-1β secretion, which is partially dependent upon the NLRs Nalp3 and Ipaf. WT, Nalp3^−/−, or Ipaf^−/− BMM were stimulated with LPS to induce proIL-1β expression before infection with WT or LLO-deficient L. monocytogenes (MOI 6). IL-1β secretion was assessed by ELISA as a measure of caspase 1 activation at (A) 1 h or (B) 4 h post infection. Error bars, SD. Representative of three independent experiments.