Aim: To investigate the relationship of alveolar macrophages and inhaled nanoparticles (NPs) in the lung.
Materials & methods: Rats were exposed by inhalation to 16-nm gold NPs for 6 h, and ultramicroscopic observation on the frequency and localization of gold NPs within lavaged macrophages was performed for 7 days.
Results & discussion: The majority of macrophages examined on day 0 (94%) contained internalized gold NPs, and the percentage decreased to 59% on day 7. Gold NPs were exclusively found within cytoplasmic vesicles. On day 0, most gold NPs appeared to be individual or slightly agglomerated, while they were frequently agglomerated on day 7.
Conclusion: Alveolar macrophages efficiently internalized NPs by endocytosis, and rearrangements of vesicles and of NPs in the vesicles of macrophages occurred.