Purification of hemopoietin 1: a multilineage hemopoietic growth factor.

Hemopoietin 1 (H-1) and the mononuclear phagocyte specific growth factor CSF-1 act synergistically on developmentally early bone marrow cells to generate primitive CSF-1 receptor-bearing cells. The H-1 activity of the serum-free medium conditioned by the human urinary bladder carcinoma cell line 5637 was shown to result from the sum of the activities of two charged species (pI approximately equal to 4.8, approximately equal to 85%; pI approximately equal to 5.3, approximately equal to 15%) of similar size. No qualitative difference in the biological activity of these two species was detected. A four-step procedure, involving batch DEAE-cellulose chromatography, chromatofocusing, gel filtration, and hydrophobic chromatography has been developed for the major (pI approximately equal to 4.8) species. H-1 was purified approximately 65,000-fold and recovered as 32% of the total activity of the starting material. The lowest concentration yielding maximal biological activity was approximately equal to 0.25 ng/ml. The 125I-labeled purified H-1, in either native or reduced form, behaved as a homogeneous single band that coelectrophoresed with the biological activity of purified H-1 on sodium dodecyl sulfate gel electrophoresis (NaDodSO4/PAGE). The molecular mass of the purified reduced H-1, determined by NaDodSO4/PAGE was approximately equal to 17 kDa. Recent studies indicate that the purified H-1 is a multilineage hemopoietic growth factor.