Pulmonary exposure to residual oil fly ash (ROFA) impairs lung defense mechanisms. The objective of the present work was to examine the effect of ROFA solubility on pulmonary bacterial clearance and mortality after infection. ROFA was collected from a precipitator at Slithe, Inc. Power Plant #7, Everett, MA. The collected sample (ROFA-total) is suspended in saline, incubated for 24 hr at 37 C, centrifigured, and separated into soluble (ROFA-sol) and insoluble fractions (ROFA-insol). The metal composition of the fractions as determined by inductively-coupled plasma mass spectroscopy. Al, V, Mn, Co, Zn, and Ni were present in significant amounts in the soluble fraction. Sprague Dawley rats, weighing 250 g, were dosed intratracheally with saline (vehicle, control), ROFA-total (1 mg/100g body wt), ROFA-sol, and ROFA-insol. Three days later, the rats were inoculated intratracheally with 5 x 10^5 Listeria monocytogenes. Mortality was monitored over the course of the treatment period. At 3, 5, and 7 days post-bacteria innoculation, left lungs were removed, homogenized, and the number of colony-forming units were counted after an overnight incubation. Pre-exposure to ROFA-total and ROFA-sol dramatically slowed the pulmonary clearance of L. monocytogenes as compared to the other groups. No difference in bacterial clearance was observed when comparing the ROFA-insol and control groups.
American Journal of Respiratory and Critical Care Medicine. Abstracts of the American Thoracic Society 2001 International Conference, May 18-23, 2001, San Francisco, California