Comparison of the Pulmonary Defenses against Streptococcal Infection in Rats andMice Following 03 Exposure: Differences in Disease Susceptability and Neutrophil Recruitment

摘要

To investigate the mechanism of disease protection in rats, antibacterialdefenses of two strains of mice and F344 rats were compared. O3 exposure (3 hr, 0.4 or 0.8 ppm) and infection with S. zooepidemicus resulted in a dose-dependent proliferation of bacteria in the lungs of mice and high mortality. Polymorphonuclear leukocytes (PMNs) were observed in severely affected individuals 2 or more days postinfection and did not alter the fatal infection. In contrast, microbial inactivation was only impaired in O3-exposed rat lungs during the first 48 hr after infection. In these animals PMNs could be isolated from bronchoalveolar lavage fluid between 6 and 48 hr postinfection with the peak response occurring at 24 hr. Pretreatment with anti-PMN serum eliminated the neutrophil influx and impaired further the bactericidal activity in ozone-exposed rats. The results suggest that inhaled streptococci are cleared normally from the mouse lung by AMs. Following exposure to O3, AM phagocytosis is reduced and the mice develop a fatal infection. Differences in antimicrobial defenses between various experimental species and humans need to be better understood in order to predict effects of air pollutants on susceptibility to infection in man.