Species comparisons of bronchoalveolar lavages from guinea pigs and rats exposed in vivo to diesel exhaust for one year.

Male Hartly guinea pigs and Fischer rats 344 were exposed to diesel exhaust (DE) concentrations at 0, 250, and 1500 micrograms/m3 in short terms, as well as long term experiments up to one year. The effects of inhaled DE on these rodents were evaluated using bronchoalveolar lavage technique. Both the morphological and functional studies of free lung cells and the biochemical and immunologic studies of the supernatant lavage fluid provided the basis for a quantitative species comparison of the pulmonary responses of exposed guinea pigs and rats versus age matched controls. Following inhalation of 250 micrograms DE/m3, there were little or no significant changes in either species. In contrast, at higher DE concentration, leukocytic infiltration and elevation of specific proteins in lavage fluids were observed in both species. The findings occurred and persisted in both species. Some of the responses were species specific (e.g., the specific type of exudative leukocytes, appearance of reactive monocytes, and different amounts of free DE particles and debris in the lavage fluid). Other responses were similar in both species. Among them, the emergence and increase of lymphocytes was evidence of immunologic responses. Biochemical data from the supernatant fluid correlates with the changes in cellular population in the lavage. The responses appear to be dose and duration dependent. These data indicate that species differences occur. However, it is clear that the alveolar macrophage and granulocytic leukocytes continue to exert effective defense at the DE dose-durations studied. In general, rats appeared more resistant to DE exposure than guinea pigs.