Granulocyte colony-stimulating factor administration to healthy volunteers: analysis of the immediate activating effects on circulating neutrophils

Abstract

In four healthy volunteers, we analyzed in detail the immediate in vivo effects on circulating neutrophils of subcutaneous administration of 300 micrograms of granulocyte colony-stimulating factor (G-CSF). Neutrophil activation was assessed by measurement of degranulation. Mobilization of secretory vesicles was shown by a decrease in leukocyte alkaline phosphatase content of the circulating neutrophils. Furthermore, shortly postinjection, Fc gamma RIII was found to be upregulated from an intracellular pool that we identified by immunoelectron microscopy as secretory vesicles. Intravascular release of specific granules was shown by increased plasma levels of lactoferrin and by upregulation of the expression of CD66b and CD11b on circulating neutrophils. Moreover, measurement of fourfold elevated plasma levels of elastase, bound to its physiologic inhibitor alpha 1- antitrypsin, indicated mobilization of azurophil granules. However, no expression of CD63, a marker of azurophil granules, was observed on circulating neutrophils. G-CSF--induced mobilization of secretory vesicles and specific granules could be mimicked in whole blood cultures in vitro, in contrast to release of azurophil granules. Therefore, we postulate that the most activated neutrophils leave the circulation, as observed shortly postinjection, and undergo subsequent stimulation in the endothelial microenvironment, resulting in mobilization of azurophil granules. Our data demonstrate that G-CSF should be regarded as a potent immediate activator of neutrophils in vivo.

Mobilization Kinetics of CD34 + Cells in Association with Modulation of CD44 and CD31 Expression during Continuous Intravenous Administration of G‐CSF in Normal Donors

“…On the basis of currently available data, G-CSF appears to have reproducible biologic activity and an acceptable safety profile in normal subjects [4,5,14,15]. The pharmacological profile of G-CSF in normal donors shows maximum serum concentrations after s.c. administration within 2-8 h [16]. Due to the short elimination half-life of G-CSF of about 3-4 h, we considered that the administration of G-CSF once or twice daily might be suboptimal.…”

rHuG‐CSF Increases the Platelet‐Neutrophil Complex Formation and Neutrophil Adhesion Molecule Expression in Volunteer Granulocyte and Stem Cell Apheresis Donors

“…In addition to upregulation of β2 integrins on PMNs, loss of L-selectin expression with treatment suggests that the cells had been activated in response to rHuG-CSF. Several in vivo and in vitro studies have documented the neutrophil-activating effect of G-CSF (9,16,17).…”

Leucocyte alkaline phosphatase identifies terminally differentiated normal neutrophils and its lack in chronic myelogenous leukaemia is not dependent on p210 tyrosine kinase activity

“…Finally, G-CSF administration was associated with a release into the circulation of LAP-positive immature granulocytes (characterized by low CD16 expression), thus suggesting that G-CSF in vivo can modulate the pathway of granulocytic maturation inducing surface expression of LAP in more immature granulocytes. Low levels of CD16 antigen expression in normal donors after exposure to G-CSF has several possible explanations, including release of immature neutrophils into the circulation, shedding of CD16 molecules as the consequence of induced cell activation and, upon in vitro culture, induction of apoptosis (Terstappen et al, 1990;Kerst et al, 1993;de Haas et al, 1994;Homburg et al, 1995). The release of immature neutrophils from the bone marrow is likely to play a more significant role in vivo for two reasons.…”