Humoral stimulators of granulocyte production.

These studies were designed to deteractivities followed different patterns. mine whether colony stimulating factor In particular, CSF peaked and was (CSF) and diffusible granulocytopoietic declining 24 hr following endotoxin at stimulator (DGS) represented a single which time DGS was not yet detectsubstance which stimulates the proable. Then, as serum CSF fell, the DGS duction of granulocytes in vitro and activity rose. These data support the in vivo. The effect of endogenous CSF concept that the DGS activity detectupon DGS activity was studied after able with short term Millipore chamber injection of 40 g endotoxin. This recultures is not due to CSF and sugsuited in both DGS activity and high gests the effects of CSF in vitro and serum CSF levels, but the time of DGS in vivo are due to different factors. appearance and duration of the two GRANULOCYTE PRODUCTION can be stimulated both in vitro and in vivo by humoral agents. Colony stimulating factor (CSF), capable of stimulating granulocyte and macrophage colony formation in vitro’3 is present in various mammalian serums and urines and can be produced by conditioning medium with various tissues.4 CSF has been prepared in concentrated and partially purified form,5#{176} and has been shown to be a glycoprotein with a molecular weight of 45,000. Diffusible granulocytopoietic stimulator (DGS), a humoral substance present in vivo in the body fluid of postirradiated and endotoxin injected mice,7’8 has been shown to stimulate granulocyte production in ceiltight Millipore chambers implanted intraperitoneally. Concentrated or partially purified DGS has not yet been prepared. The purpose of the present studies was to determine whether the biologic activities of CSF and DCS are due to the same or different factors. This was approached by inducing endogenous CSF production with endotoxin and measuring DGS and CSF activity at subsequent intervals.