Abstract
The present study examined the temporal pattern and localization of interleukin-1 (IL-1), tumor necrosis factor α (TNFα) and inducible nitric oxide synthase (iNOS) expression in lung tissue undergoing foreign-body granuloma formation. Pulmonary granulomas were induced by the intratracheal injection of dextran beads into genetically high granuloma responder, carrying Begs, (BALB/c) and low responder, carrying Bcgγ, (C3H/HeJ and DBA/2) mice.
In BALB/c mice, IL-1α and iNOS were induced mostly in the cells accumulated around the beads and also in some bronchiolar epithelial cells during the early phase, whereas TNFα was induced in the cells around the beads at later resolution phase. By contrast, in low responder mice, an increase in the expression of IL-lα and iNOS was detected in lung macrophages as well as in alveolar cells and bronchiolar epithelial cells on day 1, but that of TNFα was not detected throughout the period.
These results suggest that IL-1 and nitric oxide produced by recruited macrophages may take part in the early, macrophage-dependent phase of granuloma formation whereas TNFα may be more crucial as a mediator responsible for the difference in innate resistance or susceptibility to granuloma formation.
