Standardized bioassay for bone marrow colony stimulating factor in human urine: Levels in normal man

A quick, reproducible method has been devised for the quantitative concentration of human urinary colony-stimulating factor (CSF) for assay using agar cultures of bone marrow cells. The method, utilizing batch chromatography on calcium phosphate gel, enables a number of urine samples to be processed simultaneously and results in a purification of CSF with concomitant removal of inhibitors of colony formation. Equations developed to describe dose-response curves allow the activity of CSF preparations to be determined with reference to a stable standard preparation relatively independently of variations encountered in culture conditions. A computer program has been used for the calculation of effective CSF concentrations from observed dose-response curves. A re-investigation of the urinary excretion of CSF in normal man has been made using the above techniques. Twenty four hour CSF outputs of 94 individuals aged 3 to 65 years were approximately symmetrically distributed about their mean value of 93,700 units and activity was detected in every urine specimen examined. Approximately one third of the subjects over the age of 65 had CSF outputs above 220,000 units, compared with only 3 individuals of the 3 to 65 age group. The elevated CSF outputs of older people were specifically elevated with respect to urine protein. Daily CSF output varied significantly in individual subjects, but no periodicity was detected in these variations. No diurnal variation was observed in CSF excretion in 4 subjects. The availability of a standard urine preparation of known colony-stimulating activity should facilitate interlaboratory standardization of the assay of CSF levels in patients with various disease states.