SERUM HALF-LIFE AND ORGAN DISTRIBUTION OF RADIOLABELED COLONY STIMULATING FACTOR IN MICE

Abstract

Granulocyte-macrophage colony stimulating factor (GM-CSF) from mouse lung conditioned medium has recently been purified. This GM-CSF was radioiodinated using the chloramine T method, but dimethylsulfoxide was needed to prevent the loss of biological activity during the iodination. 125I-labeled GM-CSF was isolated from the reaction mixture by gel filtration and affinity chromatography with concanavalin A-Sepharose. One hour after intravenous injection of 125I-labeled GM-CSF almost 80% of the radioactivity was still localized in the serum. 125I-labeled GM-CSF was cleared from the blood of C57BL mice with a serum half-life of 7.3 +/- 1.3 hours. Six hours after intravenous injection 125I-GM-CSF ..