Murine inflammatory factor co-chromatographs with murine interleukin-2 activity

1. In a study of the in vivo effects of semi-purified mouse interleukin-2 (IL-2), inflammatory activity indicated by edema and plasma protein extravasation (PPE) was detected in those fractions having IL-2 activity. 2. The molecular weight of the inflammatory factor activity from conditioned medium was 30 to 48 kDal on the basis of gel filtration on Sephadex G75. 3. The edema, characterized as maximum paw thickness, occurred at 4 h, whereas the PPE peak (measured with 125I-albumin) occurred 1.5 to 3 h after injection. 4. Both edema and PPE were inhibited by dexamethasone or indomethacin, suggesting the involvement of prostaglandins in the process. 5. This inflammatory activity may be partly responsible for some of the in vivo activities ascribed to IL-2.