Although multiple studies have shown that caspase-8 can directly cleave pro-IL-1β into mature IL-1β in circumstances such as TNF-α-induced systemic inflammatory response syndrome (SIRS) (46, 47), mature IL-1β fragments were undetectable in caspase-1-deficient macrophages upon nigericin treatment (Figure 6). This evidence concerns the gene IL1B and systemic inflammatory response syndrome.