ACCELERATION OF HEMATOPOIETIC RECOVERY IN DOGS AFTER EXTENDED-FIELD PARTIAL-BODY IRRADIATION BY TREATMENT WITH COLONY-STIMULATING FACTORS -RHG-CSF AND RHGM-CSF

Purpose: The influence of treatment with the two colony-stimulating fa ctors, rhG-CSF and rhGM-CSF, on the hemopoietic recovery in aplastic b one marrow sites after extended-field irradiation was studied in a can ine model. Methods and Materials: The dogs received irradiation of the cranial part of their body with a single dose of 11.7 Gy, comprising similar to 72% of the total bone marrow mass. Anatomically this type o f exposure corresponds to upper body irradiation (UBI) as employed und er clinical conditions. Treatment with both the CSFs was employed for 7 days by daily injections of 30 mu g/kg, starting 24 hr after irradia tion. Results: Treatment with rhGM-CSF did not completely prevent the initial decrease of the granulocyte counts, but caused an accelerated, though incomplete, recovery in the period from day 5 to day 15, In co ntrast, treatment with rhG-CSF caused two phases of granulocytosis and an early recovery to normal levels at day 11 after irradiation. Treat ment with rhG-CSF, but not with rhGM-CSF, was associated with a strong supra-normal increase of progenitor cells in the blood within the fir st 8 days and an accelerated hemopoietic recovery in the irradiated si tes particularly within the first 7 days after the exposure. Conclusio ns: These results indicate that under conditions of partial-body irrad iation short term treatment with G-CSF is superior to GM-CSF in initia ting the hemopoietic recovery on the basis of endogenous stem cell see ding. (C) 1997 Elsevier Science Inc.