Comparison of the phagocytic response of rat and hamster alveolar macrophages to man-made vitreous fibers in vitro

Rats and hamsters are well known for their disparate response to inhaled mi neral fibers/particles. Alveolar macrophages (AM) play an important role in the pulmonary clearance and retention of mineral fibers/particles mainly t hrough the process of phagocytosis, The aim of this study was to investigat e whether there exist differences in the phagocytic response and release of reactive oxygen species (ROS) between rat and hamster AM upon exposure to man-made vitreous fibers (MMVF) in vitro. AM were obtained by bronchoalveol ar lavage and macrophage-enriched cultures were exposed to MMVF10 and MMVF2 1 fibers for 20 h. The phagocytic response of macrophages was determined by computer- assisted video-microscopy and the superoxide anion production wa s evaluated by cytochrome c reduction. A significantly higher percentage of rat AM underwent frustrated phagocytosis of both types of MMVF compared to hamster AM. This was associated with a higher ROS release by rat AM compar ed to hamster AM. These data may help to explain the cellular mechanisms un derlying the disparate pulmonary response of rat and hamster to inhaled par ticulate matter.