Binding of 125I‐labeled granulocyte colony‐stimulating factor to normal murine hemopoietic cells

Abstract

The binding of granulocyte colony‐stimulating factor (G‐CSF) to murine bone marrow cells was investigated using a radioiodinated derivative of high specific radioactivity which retaine full biological activity. The binding was time‐and temperature‐dependent, saturable and highly specific. The apparent dissociation constant for the reaction was 60–80 pM at 37°C and 90–110 pM at 4°C, similar to that found for the binding of G‐CSF to murine leukemic cells (WEHI‐3B D+) and significantly higher than the concentration of G‐CSF required to stimulate colony formation in vitro. Autoradiographic analysis confirmed the specificity of binding since granulocytic cells were labeled but lymphocytes, erythr..