Endobronchial inflammation following Pseudomonas aeruginosa infection in resistant and susceptible strains of mice.

The early endobronchial inflammation induced by Pseudomonas aeruginosa infection varies in resistant and susceptible strains of mice. Mice of the DBA/2 strain are severely afflicted by the infection, with a high bacterial burden accumulating rapidly following inoculation and a high mortality rate occurring. Mice of the BALB/c strain are resistant to infection and clear the bacteria within 3 to 7 days. Infection of (BALB/c x DBA/2)F1 hybrid mice showed that the resistance to lung P. aeruginosa infection is inherited as a dominant trait. Mice of the A/J and C57BL/6 strains were found to have an intermediate phenotype to Pseudomonas aeruginosa infection when compared with BALB/c and DBA/2 strains. The decrease in the bacterial load seen early after infection coincided with a steady and strong recruitment of inflammatory cells to the bronchoalveolar spaces of mice of the resistant BALB/c strain. On the other hand, the recruitment of inflammatory cells to the lungs of mice of the susceptible DBA/2 strain was deficient, resulting in the failure to control bacterial multiplication. Chemotactic factors, proinflammatory cytokines, and the number and function of recruited inflammatory cells may play major roles in the determination of the genetic resistance to lung infection with P. aeruginosa in a normal immunocompetent host.