CASP1 and cystic fibrosis: However, when HBECs were stimulated with LPS, followed by ATP, a specific NLRP3 inflammasome activating signal that nucleates NLRP3 assembly with ASC, pyrin and caspase-1, IL-18 secretion was upregulated in CF-associated mutant cell lines, IB3-1 (p<0.0001) and CuFi-1 (p<0.0001) relative to the BEAS-2B control.