However, anti-neutrophil cytoplasmic autoantibodies directed against BPI (BPI-ANCA) found in up to 83% of people with CF (PwCF; Theprungsirikul et al., 2021b) inhibit the bactericidal function of BPI (Schultz et al., 2004; McQuillan et al., 2020). This evidence concerns the gene BPI and cystic fibrosis.