RESUMEN
100 mug/kg of recombinant human granulocyte colony - stimulating factor was injected twice daily into normal adult CF1 female mice for a period of 15 days. After that time was have observed a decrease (59)Fe marrow incorporation with a parallel increase in the spleen. During the first 9 days the marrow plus spleen erythroid cells number decreased to 60 percent of control approximately, but recovered thereafter and were not significantly different from normal values at 12 - 15 days. In addition, our studies demonstrate that the spleen erythropoiesis is quantitatively more important at the final time tham marrow erythropoiesis. For this reason, splenic compensatory erythropoiesis maintained the hematocrit values between normal ranges. Regarding the granulocytic compartment, 15 days of rhG-CSF treatment produce a marked increase in total count os splenic granulocytes (a 7.7 fold rise from control values). Marrow granulocytes shows a 2 - fold increment, but considering the absolute counts, bone marrow still was predominant as a granulopoieitc organ. Our results indicate that the spleen is a more important erythropoietic organ than marrow after 15 days of rhG-CSF treatment.