Assessment of Swine (Sus scrofa domesticus) Alveolar Macrophage Viability Associated with Heavy Metal Air Pollutants

Abstract

The impact of air pollution on airway cellular defense of pigs raised under backyard, semi-commercial and commercial conditions was investigated. Flame atomic absorption spectrometry was used to analyze Cadmium (Cd) and Lead (Pb) while manual cold vapor atomic absorption spectrometry was applied to evaluate Mercury (Hg) contents of dust particles from farms. Tests for viable counts of swine alveolar macrophages (SAM) that simulate animal responses to air pollutants, microbiological techniques for the recovery of bacterial cells and evaluation for cellular function were undertaken. Results showed that air pollution was accompanied by significant high levels of Pb and Cd. Exposure of SAM to air pollutants induced significant reduction in cell viability and the reduction was substantially contributed by the duration of exposure and the farm source of SAM and air pollutants. Significant differences in colony counts of P. multocida were recorded as effects attributed by SAM exposure, the duration of exposure to air pollutants and the farm origin of the tested SAM and air pollutants. Data that revealed high recovery counts of P. multocida were taken as a measure for altered microbicidal action of SAM against the bacterium. In vitro interaction of backyard-obtained SAM and air pollutants for 6 h does not modify the killing or microbicidal action of SAM on P. multocida but prolonging the SAM and air pollutant interface beyond 6 h may eventually weaken the microbicidal action of the cells which allows incessant yielding of high bacterial recovery counts and failure of SAM to counteract this process.