[Colony-stimulating factors in cancer chemo- and radiotherapy]

Recombinant human granulocyte colony-stimulating factor (Re Hu G-CSF) was prepared and its stimulating effect on granulocytopoiesis was examined in mice. Human G-CSF was purified to homogeneity from conditioned media of a G-CSF-producing cell line. The amino-terminal sequence was determined. By using oligonucleotides as probes, determined by the amino acid sequence, a cDNA library prepared from human macrophages was screened. The cloned G-CSF cDNA was expressed in E. coli K12MM294, and the mature protein was purified to homogeneity. Mice were given intraperitoneal injections of Re Hu G-CSF every day for 14 days. Peripheral blood granulocyte counts were examined 4, 8, 12 and 14 days after injection. Mice were sacrificed on the 14th day for histologic examinations of the bone marrow and spleen. Granulocyte counts began to increase on the 4th day and reached about 80,000/mm3 on the 14th day. Cells of granulocyte lineage were markedly increased in the bone marrow and spleen. Granulocyte precursors (CFU-C) were remarkably increased in the spleen. When mice were treated with 5-fluorouracil, cyclophosphamide or irradiation, the period of granulocytopenia was significantly shortened by subcutaneous injection of Re Hu G-CSF. These results suggest that human G-CSF play a central role in granulocyte production in vivo. The ability of Re Hu G-CSF to stimulate granulocyte production implies that this factor will be clinically useful in neutropenic patients treated with anti-cancer agents or irradiation.