Interleukin-1-like activity in the exudate of air-pouch inflammation in rats, and its participation in granuloma formation.

The in vivo production of lymphocyte activating factor (LAF) activity was investigated in the exudate of the rat air-pouch inflammation model. An inflammatory reaction was induced by lipopolysaccharide (LPS) injection into the air-pouch, and the time course of LAF activity in the exudate was investigated. LAF activity in the exudate reached a peak by 6 h, and rapidly decreased at 10 to 48 h after the LPS injection. Dexamethasone revealed strong inhibitory action on LAF activity and granuloma formation. On the other hand, indomethacin could not inhibit either of the phenomena. In conclusion, LAF (IL-1) is rapidly produced after the onset of inflammation and may participate in the subsequent granuloma formation.