Interspecies Differences in the Phagocytic Activity of Pulmonary Macrophages Subjected to Acidic Challenge

Examining interspecies differences in response to ambient pollutantsis an essential component of risk assessment. The potentialhazard to public health from the inhalation of acid sulfateaerosols is of current concern. A significant biological targetis the pulmonary macrophage, which provides a primary defenseof the respiratory region of the lungs. One essential functionof these cells is phagocytosis of particles. This study assessedthe effects of acidic environments on the phagocytic activityof pulmonary macrophages obtained by lavage from humans andthree species of laboratory animals commonly used in acid aerosoltoxicology studies, namely, rats, rabbits, and guinea pigs.Cells were incubated with polystyrene latex particles in mediaacidified by addition of sulfuric acid. The percentage of cellswhich were phagocytic, as well as the relative number of particlesingested by these cells, was found to decrease with increasingacidity for all species. The ranking of response in order ofdecreasing sensitivity to acidic challenge was as follows: guineapig>rat>rabbit>human.