Stimulation of prostaglandin E2 and bone resorption by recombinant human interleukin 1 alpha in fetal mouse bones

Recombinant human interleukin 1 alpha (rhIL-1 alpha) stimulates prostaglandin E2 and bone resorption in cultured forearm bones of fetal mouse in a dose-dependent manner: the minimal rhIL-1 alpha to elicit a significant bone resorption was 1.6 ng/ml (89 pM). The half maximal concentrations to elicit bone resorption and thymocyte proliferation were 3.3 ng/ml (183 pM) and 0.31 ng/ml (17 pM), respectively. The bone resorbing activity induced by IL-1 was partially inhibited by indomethacin and hydrocortisone, and completely inhibited by anti-IL 1-antibody. There was a good correlation between PGE2 production and bone resorption induced by IL-1 alpha. These results suggest that rhIL-1 alpha stimulates bone resorption at approximately 10 times the concentrations necessary for thymocyte proliferation and that PGE2 produced in the bone is at least in part involved in osteoclastic bone resorption.