Effect of chemotactins released by Staphylococcus aureus and Pseudomonas aeruginosa on the murine respiratory tract

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Abstract
S. aureus, the P. aeruginosa temperature-sensitive (ts) mutant A/10/25 and the P. aeruginosa parental wild type were aerosolized to complement C5-deficient mice, and the total number of polymorphonuclear leukocytes (PMN) recovered by lung lavage was determined 4 h after aerosol exposure. S. aureus induced a slight recruitment of PMN as compared with the effect of a saline aerosol. Both wild-type P. aeruginosa and the ts mutant induced a significant PMN recruitment of a magnitude .apprx. 180 times higher than that produced by S. aureus. Gentamicin-killed ts P. aeruginosa induced a PMN recruitment of a magnitude similar to that produced by live ts P. aeruginosa. Thorough washing of the bacteria, however, removed .apprx. 90% of the chemotactic activity. Exposure of the animals to a ts P. aeruginosa culture supernatant aerosol induced significant PMN recruitment into the lower airways. The same culture supernatants were chemotactic for mouse PMN in a dose-dependent fashion when tested in vitro in the absence of serum. Culture supernatants of S. aureus exhibited weak chemotactic activity in vitro and did not induce PMN recruitment in the lungs when aerosolized to DBA/2J mice. Chemotactins released by P. aeruginosa may be an important virulence factor and play a significant role in lung tissue damage.