WT, NAIP-/- clone #12, and two independent clones of NLRC4-/- THP-1 monocyte-derived macrophages were primed with 100 ng/mL Pam3CSK4 for 16 hours. Cells were then infected with PBS (Mock), WT S. Typhimurium, or ΔsipB S. Typhimurium at an MOI = 20 for 6 hours. Release of IL-1β (A, B) and IL-18 (C, D) into the supernatant were measured by ELISA. Immunoblot analysis was performed on supernatants (sup) for mature IL-1β and on lysates for pro–IL-1β and β-actin as a loading control. ns–not significant, ***p < 0.001, ****p < 0.0001 by Šídák’s multiple comparisons test (A, C) or Dunnett’s multiple comparisons test (B, D). Error bars represent the standard deviation of triplicate wells from one experiment. Data shown are representative of at least three independent experiments.