Purification to homogeneity of a human hematopoietic growth factor that stimulates the growth of a murine interleukin 3-dependent cell line.

A human lymphokine derived from the 5637 bladder carcinoma has been purified to homogeneity by using sequential reverse-phase high pressure liquid chromatography. A high recovery of biological activity is obtained by using this purification. The NH2-terminal amino acid sequence shows no homology to human interleukin 1 (IL 1), human IL 2, murine IL 3, or human granulocyte-macrophage colony-stimulating factor. The growth-promoting properties of the 5637-derived factor can be rapidly assayed by using the murine IL 3-dependent 32D c1-23 cell line. The amino acid sequence described is identical to that recently described for a human granulocyte colony-stimulating factor.