Haematological Effects in Mice of Partially Purified Colony Stimulating Factor (CSF) Prepared from Human Urine

Summary. Single injections of partially purified human urine preparations containing 10 000–20 000 units of colony stimulating factor (CSF) produced a monocytosis and polymorph leucocytosis in neonatal C57BL mice which was maximal at 48 hr. Adult C57BL mice developed a monocytosis, and although no polymorph leucocytosis developed, labelling studies suggested an increased rate of granulopoiesis. In adult mice the injected CSF preparations did not alter total bone‐marrow cellularity but increased the percentage of primitive granulocytes and caused an increase in the number of in vitro colony‐forming cells and granulocytic cluster‐forming cells. The preparations also increased the number of bone‐marrow cells able to initiate colony and cluster formation immediately after culture of the bone‐marrow cells in agar. The results suggest that CSF in vivo may stimulate both granulopoiesis and monocyte formation in an action similar to its action in agar cultures of bone‐marrow cells.