Stimulator of proliferation of spleen colony-forming cells in acute sterile inflammation.

ABSTRACT

The presence and activity of a spleen colony-forming cell (CFU-S) proliferation stimulator was investigated in rat bone marrow after induction of sterile inflammation. Wistar rats were treated intraperitoneally with two 15 ml injections of 3.5% polyvinylpyrrolidone (PVP) at 18 h intervals, and the presence of CFU-S proliferation stimulator determined in bone marrow 6, 20 and 24 h after the first injection. The marrow of these mice was used to condition medium which was then fractionated using Amicon Diaflo ultrafiltration membranes. The 30-50 kDa fraction, taken from 20h post-PVP-bone marrow extract, was found to induce cycling of d8-CFU-S in normal mouse bone marrow. This activity was not related to the presence of interleukins-1, -2 or -6 like activities in the material tested. The results demonstrate the existence of CFU-S proliferation stimulator in the bone marrow of rats with sterile inflammation (i.e. in an in vivo tissue response to non-specific cell stimulation), similar to that originally described as a macrophage product in mouse bone marrow after treatment with a variety of cytotoxic agents.