Seven-Day Administration of Recombinant Human Granulocyte Colony-Stimulating Factor to Newborn Rats: Modulation of Neonatal Neutrophilia, Myelopoiesis, and Group

Single-pulse administration of rhG-colony-stimulating factor (CSF) to neonatal rats was previously demonstrated to induce peripheral neutrophilia and modulate bone marrow (BM) neutrophi l storage and prol i ferat ive pools (NSP + NPP). In this study, we investigated the prolonged effects of 7 days of rhG-CSF therapy (5 pg/kg/per day). Sprague-Dawley newborn rats (524 hours) were injected intraperitoneally (IP) (daily for 7 days) with rhG-CSF or phosphate-buffered saline/ human serum albumin (PBS/ HSA). RhG-CSF induced a significant early and late peripheral neutrophilia: 6,905 ? 1,625 (day 1 ) and 9,223 ? 51 5 pL (day 7) v 1,275 ? 9O/pL ( P I .OW1 1. In addition, 7 days of rhG-CSF resulted in a significant increase in the BM NSP: 3.247 ? 19O/pL v 1,677 ? 339IpL (P 5 .001). There was, however, no depletion or significant change in the BM NPP. Seven days of rhG-CSF also induced a mild increase in BM CFU-GM colony formation ( P I .01). There was, however,