CR1 and cystic fibrosis: In addition, it has been reported that in vitro NE is capable of creating an “opsonin-receptor mismatch” by cleaving complement receptor 1 (CR1) from the neutrophil surface and C3bi of opsonized Pseudomonas aeruginosa [79], impairing clearance of this bacteria commonly found in the CF airway and associated with mortality [80].