ENDOBRONCHIAL INFLAMMATION FOLLOWING PSEUDOMONAS-AERUGINOSA INFECTIONIN RESISTANT AND SUSCEPTIBLE STRAINS OF MICE

The early endobronchial inflammation induced by Pseudomonas aeruginosa infection varies in resistant and susceptible strains of mice. Mice o f the DBA/2 strain are severely afflicted by the infection, with a hig h bacterial burden accumulating rapidly following inoculation and a hi gh mortality rate occurring. Mice of the BALB/c strain are resistant t o infection and clear the bacteria within 3 to 7 days. Infection of (B ALB/c x DBA/2)F-1 hybrid mice showed that the resistance to lung P. ae ruginosa infection is inherited as a dominant trait. Mice of the A/J a nd C57BL/6 strains were found to have an intermediate phenotype to Pse udomonas aeruginosa infection when compared with BALB/c and DBA/2 stra ins. The decrease in the bacterial load seen early after infection coi ncided with a steady and strong recruitment of inflammatory cells to t he bronchoalveolar spaces of mice of the resistant BALB/c strain. On t he other hand, the recruitment of inflammatory cells to the lungs of m ice of the susceptible DBA/2 strain was deficient, resulting in the fa ilure to control bacterial multiplication. Chemotactic factors, proinf lammatory cytokines, and the number and function of recruited inflamma tory cells may play major roles in the determination of the genetic re sistance to lung infection with Pc aeruginosa in a normal immunocompet ent host.