GRANULOCYTE-COLONY-STIMULATING FACTOR TREATMENT OF MICE MODULATES DIFFERENTLY THE SENSITIVITY OF BLOOD AND BONE-MARROW HEMATOPOIETIC PROGENITORS TO RETROVIRAL VECTOR INFECTION

The effect of recombinant human granulocyte colonY-stimulating factor (G-CSF) administration to mice on the retroviral-mediated transfer of the selectable marker gene neo to hematopoietic cells was studied. Aft er G-CSF treatment, blood mononuclear cells and bone marrow cells were infected with the retrovirus, and the efficiency of gene transfer int o myeloid progenitors was increased in peripheral blood and decreased in bone marrow cells. Bone marrow four to six months after transplanta tion from G-CSF treated mice revealed the presence of the transferred neo gene in 4 out of 104 mice, which is an eightfold lower proportion than in the control group. These data suggest that G-CSF in vivo treat ment decreases bone marrow sensitivity and increases the sensitivity o f peripheral blood cells to retroviral infection.