Prolonged survival of mice with myeloid leukemia by subcutaneous injection of recombinant human G-CSF

We studied the effect of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on leukemia development and survival of mice with leukemia by using a radiation-induced myeloid leukemia cell line (C2M) with A-type phosphoglycerate kinase (PGK) as marker isoenzyme. C3H/He mice with B-type PGK were inoculated with 2 x 10(6) C2M cells through the tail vein. From the next day, they received a daily subcutaneous injection of 1 microgram rhG-CSF or control solution. The survival of rhG-CSF-treated recipients of C2M was significantly longer than control-solution-treated recipients. In rhG-CSF-treated recipients, not only spleen weight but also the number of blasts in hemopoietic organs was less than those in control recipients. While there was a remarkable decrease in bone marrow content of CFU-GM in control recipients, the content in rhG-CSF-treated recipients was comparable to that in normal mice. A reduced bone marrow and spleen content of leukemic colony-forming cells (L-CFU) was observed in rhG-CSF-treated recipients in comparison with control recipients. The electrophoretic analysis of PGK phenotypes of hemopoietic organs indicated the delayed appearance of A-type PGK from C2M cells in rhG-CSF-treated recipients. From these findings, we concluded that the injection of rhG-CSF delayed the onset of leukemia and improved the survival and several hematological parameters by suppressing C2M cells in recipient mice.