Calpain is involved in IL-1β release induced by <i>L. monocytogenes</i>, but not <i>S.</i> typhimurium infection.

<p>LPS-primed peritoneal macrophages were pre-treated for 20 min with DMSO, MDL28170 (50 µM) or Ca074Me (50 µM) before infection with wt or <i>ΔhlyΔplcB</i> strains at a MOI of 5 for 1 h. Gentamicin was then added and the culture was continued for another 3 h before supernatants were collected. Levels of IL-1β (A) or IL-1α (B) in the supernatants were measured by ELISA and western blot (precursor form 31 kDa and mature form 17 kDa). ELISA data are shown as the mean ± SD, n = 4 for MDL28170 and n = 5–7 for Ca074Me. Western blots are representative of n = 4. LPS-primed peritoneal macrophages pre-treated for 20 min with DMSO, MDL28170 (50 µM), calpeptin (50 µM), Ca074Me (50 µM) and YVAD (100 µM) and infected with <i>S.</i> typhimurium at a MOI of 30 for 1 h. After addition of gentamicin the culture was continued for another 3 h when supernatants were collected. Levels of IL-1β (C) were measured by ELISA. Data shown as the mean ± SD, n = 4–6. **P<0.01, *P<0.05.