SERUM LEVELS OF G-CSF, IL-3, IL-6 AND GM-CSF AFTER A SINGLE INTRAPERITONEAL DOSE OF RHG-CSF IN LETHALLY IRRADIATED B6D2F1 MICE

The objective of this study was to assess the pharmacokinetics of rhG- CSF after a single intraperitoneal injection 2 h post-TBI in B6D2F1 le thally irradiated mice and to analyze the effect of rhG-CSF on the end ogenous response of interleukin-3 (IL-3), interleukin-6 (IL-6) and gra nulocyte-macrophage colony-stimulating factor (GM-CSF) in these animal s. For comparison, these cytokine serum levels have also been measured in nonirradiated mice. The serum concentrations of rhG-CSF in irradia ted mice were higher than in nonirradiated mice at all time points dur ing the first 60 min after injection. Furthermore, rhG-CSF administrat ion failed to induce detectable endogenous serum levels of IL-3, IL-6 and GM-CSF, at least in the 72-hour period after administration of the rhG-CSF. The radioprotective effect of rhG-CSF in lethally irradiated mice is not mediated by an increase in endogenous serum levels of the se three cytokines.