Affinity isolation of the interleukin-3 surface receptor

Interleukin-3 (IL-3) is a pluripotent hematopoietic growth factor which can stimulate both proliferation and differentiation of progenitor cells. Using the factor dependent NSF-60 and FDC-P1 cells, which possess specific, high affinity binding sites for 125 I-IL-3 (i. e. K D 9.5 and 10.7 × 10 −11 M, respectively) the IL-3 surface receptor has been isolated. Using two separate affinity techniques the IL-3 receptor identified from both cell types was invariant. The IL-3 receptor is a protein of molecular weight 65–70,000 daltons.