S18 potently inhibited cytokine secretion (IL-18 p=0.0052; IL-1β p=0.0100) and caspase-1 activity exclusively in cells with CF-associated mutations (Figure 5C, Figure 5—figure supplement 1), whereas EIPA had no effect (Figure 5—figure supplement 1A,C,D,E). Here, IL18 is linked to cystic fibrosis.