Cellular and biochemical response of the human lung after intrapulmonary instillation of ferric oxide particles

Bronchoalveolar lavage (BAL) was used to sample lung cells and biochemical components in the lung air spaces at various times from 1 to 91 d after int rapulmonary instillation of 2.6 mu m-diameter iron oxide particles in human subjects. The instillation of particles induced transient acute inflammati on during the first day post instillation (PI), characterized by increased numbers of neutrophils and alveolar macrophages as well as increased amount s of protein, lactate dehydrogenase, and interleukin-8 in BAL fluids. This response was subclinical and was resolved within 4 d PI. A similar dose-dep endent response was seen in rats 1 d after intratracheal instillation of th e same particles. The particles contained small amounts of soluble iron (24 0 ng/mg) and possessed the capacity to catalyze oxidant generation in vitro . Our findings indicate that the acute inflammation after particle exposure may, at least partially, be the result of oxidant generation catalyzed by the presence of residual amounts of ferric ion, ferric hydroxides, or oxyhy droxides associated with the particles. These findings may have relevance t o the acute health effects associated with increased levels of ambient part iculate air pollutants.