A novel model for human interstitial lung disease: Hapten‐driven lung fibrosis in rodents

A novel model is described of chronic pulmonary fibrosis in rodents. The condition is induced by a single intratracheal instillation of a well‐characterized fluorescent haptenic antigen, fluorescein isothiocyanate (FITC), into non‐immune animals. This results in an acute inflammatory response involving a granulocytic infiltrate, which disappears over a week and is replaced by a chronic mononuclear infiltrate in which T lymphocytes predominate. Over several months, a chronic patchy fibrosis is accompanied by a sustained mononuclear interstitial infiltrate localized at sites of persistent FITC deposition. Where no FITC is present, the lung tissues are apparently normal. An immune response is mounted, as measured by the appearance of specific anti‐FITC serum antibodies. This model has relevance to the pathogenesis of some forms of human interstitial lung disease.