Decreased clearance of Pseudomonas aeruginosa from airways of mice deficient in lysozyme M

Lysozyme is a ubiquitous and abundant, cationic, antimicrobial polypeptide of leukocytes and epithelia, but its biological function in host defense is largely unexplored. To ascertain the role of lysozyme during bacterial infection of murine airways, we exposed the airways of lysozyme M-deficient (lys M-/-) mice to the pulmonary pathogen Pseudomonas aeruginosa and examined the host's response to infection. Despite partial compensation as a result of the appearance of lysozyme P in the infected airways of lys M-/- mice, these lys M-/- mice showed decreased clearance of P. aeruginosa compared with their lys M+/- or lys M+/+ littermates. Lysozyme contributes to optimal clearance of P. aeruginosa from the murine airways.