EFFECT OF RECOMBINANT HUMAN GRANULOCYTE-COLONY-STIMULATING FACTOR TREATMENT OF MICE ON SPLEEN COLONY-FORMING UNIT NUMBER AND SELF-RENEWAL CAPACITY

The aim of this investigation was to find out whether the self-renewal capacity of spleen colony-forming units (CFU-S) changed after treatment of CBF1 (CBA-LacxC57B1/6) F1 female mice with granulocyte colony-stimulating factor (G-CSF). In addition, the possibility of synergism between erythropoietin (Epo) and G-CSF in blood stem cell mobilization was studied. Twenty-five and 250 mu g/kg/d injections of recombinant human (rh) G-CSF expanded the number of CFU-S in peripheral blood four- and 32-fold. The self-maintenance potential of CFU-S did not change significantly. The treatment of mice with 250 mu g/kg/d rhG-CSF resulted in a two-fold increase of spleen cellularity and a 15-fold augmentation of CFU-S number, without noticeable changes in their self-renewal capacity. Moderate changes in CFU-S number were observed after Epo administration in spleen and peripheral blood; however, no significant synergistic effect of Epo was detected with either dose of rhG-CSF. The multifold increase of CFU-S number in peripheral blood following rhG-CSF administration, with no reduction in their generating potential, suggests that rhG-CSF-mobilized blood stem cells provide an appropriate source for reconstitution of the hematopoietic system.