Binding of iodinated multipotential colony‐stimulating factor (interleukin‐3) to murine bone marrow cells

Abstract

Multipotential colony‐stimulating factor (Multi‐CSF or interleukin‐3) was radioiodinated to high specific radioactivity (1–4 × 105 cpm/ng) with no detectable loss of biological activity and its binding to murine bone marrow cells and factor‐dependent cell lines studied. Both the native glycosylated molecule purified from a cloned T‐cell line (LB3) and the purified non‐glycosylated recombinant molecule produced by E. coli could be radioiodinated. Comparative binding studies with these derivatives demonstrated equal binding affinities and equal numbers of binding sites on various cell types indicating that carbohydrate moieties are not involved in the binding interactions. Binding of 125I‐Mult..