Macrophage colony development: properties of colony stimulating factors from murine embryo and pregnant uterus

Extracts from embryonic and uterine tissue of mice, operationally defined as colony stimulating factor (CSF), promoted the growth of macrophage-granulocyte colonies in vitro. Uterine CSF focusses from pH 5.15 to 6.00 and embryonic CSF from pH 3.60 to 5.20, although both forms have similar biological activity. CSF is relatively resistant to denaturation but it is inactivated by periodate and dithiothreitol. Gel filtration indicates a molecular weight of 45,000 which is unchanged following treatment with insolubilized trypsin, a procedure which affords a useful purification (240-fold). Trypsin-sensitive material in CSF preparations modifies colonial form under certain conditions of culture, probably by increasing the motility of macrophages. Diaminoethane derivatives of CSF were prepared and retained biological activity at isoelectric points above pH 9.0. These derivatives may be covalently linked to Sepharose providing an insolubilized form of CSF to study interactions of CSF with the cell surface.