FIG. 4.

Caspase-1 and ASC are dispensable for L. monocytogenes-induced IL-1α secretion. Macrophages derived from wt (black column), caspase-1^−/− (white column), or ASC^−/− (gray column) mice were infected with the L. monocytogenes wt or Δhly strain at a MOI of 5 for 1 h. After addition of gentamicin, the culture was continued, and expression of IL-1α mRNA was measured at 3 h after infection (A). The amount of IL-1α in the culture supernatant was determined at 18 h after infection (B). In addition, Western blotting was carried out to detect pro-IL-1α in the cell lysate and mature IL-1α in the culture supernatant at 18 h after infection (C). Similar results were obtained in three independent experiments. (-), no infection.