The release of interleukin-1-like activity by macrophages in two models of immunological inflammation in the rat.

Interleukin-1 (IL-1) is a putative mediator of inflammation released by activated macrophages in vitro. The IL-1 release by rat macrophages collected either from exudates in pertussis-induced air pouches or from the peritoneum during adjuvant arthritis has been investigated. In air pouch inflammation LPS-stimulated macrophages collected from sensitized animals release more IL-1 than cells from control rats at day 6 after challenge. This enhanced IL-1 release parallels the extent of mononuclear cell migration in the inflammatory lesion. In adjuvant arthritis LPS-stimulated macrophages collected from sensitized animals release more IL-1 than cells from control rats at days 16 and 23 after adjuvant injection. The secondary inflammation in arthritic rats was statistically significant at days 16 to 28. These results indicate that during immunological inflammation macrophages either from the inflamed area or from a non-inflamed region release more IL-1 than control cells. This release parallels the extent of the inflammation and may be important in its pathogenesis.