Quantitative Studies on the Stimulation of Mouse Bone Marrow Colony Growth in Vitro by Normal Human Urine

Summary Normal human urine was shown to stimulate colony formation in vitro by mouse bone marrow cells. Linear relationships were demonstrated between urine dose and the number and size of colonies stimulated to develop from a standard number of bone marrow cells. These criteria provide an assay system for quantifying levels of colony stimulating factor In human urine. A survey of factor levels in urine from normal subjects indicated that levels appeared to vary over a forty fold range and in any one subject show considerable diurnal and daily variations. Urine factor levels showed no significant variation with age, but showed a partial correlation with protein levels in the urine and were uniformly low when protein excretion was low.