Targeted modulation of acute inflammation.

Localized inflammation of the lungs was induced with the neutrophil chemoattractant, N-formylmethionylleucylphenylalanine (FMLP) in combination with magnetically responsive albumin microspheres, a drug carrier that provides efficient, extremely rapid localization in tissue. Intravenous targeting to rat lungs was accomplished by means of an external thoracic magnet. This caused progressive local accumulation of neutrophils, extravascular cell migration, and acute tissue injury. Microscopic findings favored chemotaxis as the principal mechanism of cell accumulation. This system provides a new experimental model for acute alveolar damage, a rapid in vivo assay for drugs that modulate neutrophil chemotaxis, and a new therapeutic approach to focusing inflammation in patients with chemotactic defects.