In vitro stimulation of alveolar macrophage metabolic activity by polystyrene in the absence of phagocytosis.

The technique of lucigenin-dependent phagocytic chemiluminescence was used to investigate the stimulation of metabolic activity in human alveolar macrophages on contact with polystyrene. The results were similar to those obtained using a spectrophotometric assay of superoxide release based on ferricytochrome C reduction. There was a marked stimulation of metabolic activity in the alveolar macrophages on incubation at 37 degrees in polystyrene vials which was shown to be due to contact with and adherence to the polystyrene. This could be reduced by the addition of gelatin or foetal calf serum without preventing the ability of the cells to respond to opsonized particles. By using several metabolic inhibitors it was shown that lucigenin-dependent chemiluminescence was associated with the release of superoxide at the time of adherence. The implications of these findings are discussed and it is suggested that the stimulation of alveolar macrophage metabolic activity by contact with polystyrene can contribute to the observed difference between alveolar macrophage and polymorphonuclear leucocyte oxygen consumption in the absence of phagocytosis.