Effects of high-dose granulocyte colony-stimulating factor on neutrophil functions

We evaluated the effects of high-dose recombinant human granulocyte colony-stimulating factor (rhG-CSF) therapy on N-formyl-methionyl-leucyl-phenylalanine (FMLP)-induced chemotaxis and superoxide (O ⁻₂) production in neutrophils from four patients with aplastic anaemia. The FMLP-induced chemotaxis and O ⁻₂ production in the neutrophils of all four patients were normal before the rhG-CSF treatment. After the administration of high-dose rhG-CSF, chemotaxis in agarose was decreased, adherence and O ⁻₂ production were enhanced in all the patients. An excessive increase of neutrophils with augmented adhesiveness and oxygen radical production may be harmful. Care should be taken in regard to neutrophil toxicity when high-dose G-CSF is used clinically.     

Granulocyte colony-stimulating factor down-regulates the surface expression of the human leucocyte adhesion molecule-1 on human neutrophils in vitro and in vivo

Summary. The leucocyte adhesion molecule-1 (LAM-1) is the human homologue of the murine peripheral lymph node homing receptor, MEL-14, and might play a crucial role in neutrophil localization at inflammatory sites. We have reported previously that recombinant human granulocyte colony-stimulating factor (rhG-CSF) stimulates or enhances several neutrophil functions in vivo , as well as in vitro. To further explore the possible role of G-CSF in inflammation we studied the effect of rhG-CSF on the surface expression of LAM-1 on human neutrophils, both in vitro and in vivo. The expression of LAM-1 by human neutrophils was investigated by indirect immunofluorescence using flow cytometry and monoclonal antibodies anti-Leu-8 and TQ1. A whole blood analysis was performed to minimize in vitro manipulation. Most circulating human neutrophils expressed LAM-1 on the cell surface. Brief exposure of neutrophils to rhG-CSF in vitro decreased the surface expression of LAM-1. rhG-CSF down-regulated neutrophil LAM-1 expression in a time- and dose-dependent manner. Neutrophils from healthy volunteers and from patients who were receiving rhG-CSF exhibited a decreased expression of LAM-1 after rhG-CSF administration, and the expression thereafter returned or overshot the pretreatment level after stopping rhG-CSF administration. These findings indicate that rhG-CSF down-regulates the surface expression of LAM-1 on human neutrophils in vivo , as well as in vitro , and G-CSF might participate in neutrophil-endothelial cell interaction in inflamed tissue.     

Effect of recombinant human granulocyte colony-stimulating factor administration in normal and experimentally infected newborn rats.

We investigated the effects of repetitive recombinant human granulocyte colony-stimulating factor (rhG-CSF) administration at three different doses (every 12 h times six doses, starting at 12-24 h of age) on the kinetics of neutrophil production in Sprague-Dawley rats. We determined WBC counts, differentials, the number of total nucleated cells, the myeloid mitotic pool cells (promyelocytes and myelocytes), the storage pool cells (metamyelocytes, bands, and polymorphonuclear cells [PMNs]) and the granulocyte-macrophage (granulocyte-macrophage colony-forming units, CFU-GM) and macrophage (macrophage colony-forming units, CFU-M) progenitor cells of the bone marrow, spleen, and the liver before the first dose of rhG-CSF administration and 12 h after the second, fourth, and sixth dose. Control animals were given the diluent by the same schedule. Recombinant human G-CSF-treated rats showed a significant dose-dependent increase in the number of total WBC and neutrophil counts at all time points compared to control rats. The total number of CFU-GM and myeloid mitotic pool cells (marrow plus spleen plus liver) progressively increased with age in both control and G-CSF groups, but the G-CSF treated groups showed a significantly larger number of mitotic pool cells at hour 24, continuing up to hour 72, compared to the control group. However, there was no significant difference at any time point in the number of CFU-G/GM as detected by the granulocyte-macrophage colony-stimulating factor (GM-CSF)-supported culture system. Priming of newborn rats with injections every 12 h of rhG-CSF times two doses, or six doses followed by inoculation of group B streptococci (GBS) did not significantly change the sepsis death rate of animals, although the neutrophil counts in infected rhG-CSF-primed animals were significantly larger than the infected control animals. Injection of human i.v. gammaglobulin 3 h following inoculation with GBS significantly improved the survival of animals compared to G-CSF administration or administration of the diluent alone (control). Thus G-CSF alone may not be beneficial for the treatment of neonates with sepsis. Additional work is needed to determine whether combination of G-CSF with antibiotics or other cytokines, such as GM-CSF or interleukin 6 (IL-6) may be of benefit.     

In vivo effects of recombinant human granulocyte colony-stimulating factor on normal neutrophil function and membrane effector molecule expression.

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) is now undergoing clinical trials. We investigated the effects of rhG-CSF on the function of neutrophils in vivo in healthy volunteers. rhG-CSF (0.5 micrograms/kg) was injected subcutaneously for 6 consecutive days. The number of neutrophils in peripheral blood decreased transiently within an hour, and thereafter increased 2-10-fold compared to the control 6 to 8 h after injection. The circulating neutrophils remaining during this early neutropenic period showed increases in such functions as random motility, chemotaxis, phagocytosis and superoxide anion production. On the other hand, the function of neutrophils which increased 6 to 8 h after rhG-CSF injection was normal. No decrease of neutrophil function was observed following the use of rhG-CSF. CD33-positive cells increased 3 days after rhG-CSF administration. CD11a (LFA-1) expression on the membranes circulating neutrophils decreased 6 h after rhG-CSF administration. This phenomenon suggested that neutrophils adhered to the reticuloendothelial system during neutropenia, and that there was an influx of CD11a-negative mature cells into the circulatory pool thereafter. All our findings suggest that rhG-CSF enhances the function of normal neutrophils in vivo, and that it is effective against microbial infection very soon after administration.     

Increased respiratory burst activity of neutrophils in patients with aplastic anemia: effects of granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor.

The superoxide (O2-)-releasing capacity in response to N-formyl-methionyl-leucyl-phenylalanine (FMLP) and the priming effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) and granulocyte-macrophage colony-stimulating factor (rhGM-CSF) on FMLP-induced O2-release were investigated in neutrophils from 13 patients with aplastic anemia (AA). The O2(-)-releasing capacity of AA neutrophils (0.85 +/- 0.36 nmol/5 min/1 x 10(5) cells, n = 13) was significantly (p < 0.01) increased as compared with that of normal neutrophils (0.24 +/- 0.12 nmol/5 min/1 x 10(5) cells, n = 17). There was no close relationship between the O2(-)-releasing capacity and the peripheral blood neutrophil count or the plasma concentration of C-reactive protein. The plasma concentrations of G-CSF and GM-CSF were not elevated to the detectable levels (< 0.1 ng/ml and < 0.2 ng/ml, respectively) in all patients tested. FMLP-induced O2(-)-release was further enhanced by pretreatment of cells with rhG-CSF or rhGM-CSF for 10 min at 37 degrees C, except that no significant priming by rhG-CSF was observed in five patients. The priming effect of rhGM-CSF was consistently greater than that of rhG-CSF in all patients. The i.v. administration of rhGM-CSF (6 micrograms/kg body weight/day) to one patient resulted in an increase in neutrophil O2(-)-release stimulated by FMLP. These findings indicate that neutrophils from AA patients are already primed in vivo for enhanced release of O2- and that these neutrophil functions are further potentiated by rhG-CSF or rhGM-CSF.     

Effects of rhG-CSF on neutrophil functions and bone marrow parameters in diabetic rats

Neutrophils have an important role in the host defense. The elevated serum glucose levels of diabetics affect traditional host defenses such as neutrophil counts and functions. The causes of these impairments are not clear. We aimed to investigate changes of peripheral neutrophil counts and functions and their relation with bone marrow cells in diabetic rats. Thirty-two rats were divided into four equal groups. Group 1 were controls and Groups 2 and 4 were made diabetic by a single intraperitoneal injection of streptozotocin. Granulocyte colony stimulating factor (G-CSF) was injected subcutaneously into Groups 3 and 4. White blood cell count, neutrophil counts and function and bone marrow cell count were determined. Peripheral blood cell counts, neutrophil phagocytosis index were decreased but neutrophil adhesivity index was not different in the diabetes-induced group. There was a difference in circulating white blood cell counts and neutrophil counts between the rhG-CSF treated and non-treated groups. The phagocytosis index of neutrophil in diabetic rats was significantly diminished by rhG-CSF treatment. A hyperplasia of early cells of the myeloid series in G-CSF treated groups was observed when compared with those of nontreated groups (p<0.001). A significant decrease was noted in the number of mature marrow segmented cells diabetic groups (p<0.001). Finally, G-CSF has been shown to cause neutrophilia by acting as a releasing factor for mature marrow neutrophils in diabetic rats. These results suggest that G-CSF may be used to improve nonspecific immunity in diabetic patients.     

A new bioassay for human granulocyte colony-stimulating factor (hG-CSF) using murine myeloblastic NFS-60 cells as targets and estimation of its levels in sera from normal healthy persons and patients with infectious and hematological disorders

[3H]thymidine uptake by NFS-60 cells in microcultures was found to increase in a linear fashion with the increasing doses of purified recombinant human granulocyte colony-stimulating factor (rhG-CSF). Such increases were found neither with rhG-CSF samples pretreated with rabbit anti-rhG-CSF serum nor with other human colony-stimulating factors such as granulocyte-macrophage colony-stimulating factor (hGM-CSF) or macrophage colony-stimulating factor (hM-CSF). Based on these findings, sera from normal persons and patients with severe infections or various hematological disorders were tested after dialysis using this system in order to determine whether G-CSF levels in sera can be estimated or not. In ten normal persons, five patients with acute myelogenous leukemia (AML M1, M2, and M3), five with myelodysplastic syndrome, and four with chronic myelogenous leukemia, no increases in [3H]thymidine uptake were found within the dose range of 0.4 microliters to 50 microliters. In contrast, linear dose responses parallel to a G-CSF standard curve were observed in one patient with a severe bacterial infection, four with aplastic anemia, two with acute myelomonocytic leukemia (AMMoL) (M4), and two with idiopathic neutropenia tested. From the standard curve, the probable levels of G-CSF were calculated as follows: approximately 200 pg/ml with infection, 130-220 pg/ml with aplastic anemia, 150 and 200 pg/ml with AMMoL, and 1120 and 1200 pg/ml with idiopathic neutropenia. The activities of sera were reduced by the anti-rhG-CSF serum pretreatment in the same way as documented in the case of rhG-CSF. Furthermore, the level in a patient with a severe infection became undetectable soon after elimination of the infection and blood neutrophil counts had returned to normal. These findings indicate that the microbioassay system will be useful for measuring circulating G-CSF levels which would fluctuate in accord with requirements for stimulating neutrophil production or with abnormal production of hG-CSF.     

A randomized, placebo-controlled trial of recombinant human granulocyte colony-stimulating factor administration in newborn infants with presumed sepsis: significant induction of peripheral and bone marrow neutrophilia

Host defenses in the human neonate are limited by immaturity in phagocytic immunity. Such limitations seem to predispose infected newborns to neutropenia from an exhaustion of the neutrophil reserve. Among the critical defects thus far identified in neonatal phagocytic immunity is a specific reduction in the capacity of mononuclear cells to express granulocyte colony-stimulating factor (G-CSF) after stimulation. However, the safety, pharmacokinetics, and biological efficacy of administration of recombinant human (rh)G-CSF to infected human newborns to compensate for this deficiency is unknown. Forty-two newborn infants (26 to 40 weeks of age) with presumed bacterial sepsis within the first 3 days of life were randomized to receive either placebo or varying doses of rhG-CSF (1.0, 5.0 or 10.0 micrograms/kg every 24 hours [36 patients] or 5.0 or 10.0 micrograms/kg every 12 hours [6 patients]) on days 1, 2, and 3. Complete blood counts with differential and platelet counts were obtained at hours 0, 2, 6, 24, 48, 72, and 96. Circulating G-CSF concentrations were determined at hours 0, 2, 6, 12, 14, 16, 18, 24, and 36. Tibial bone marrow aspirates were obtained after 72 hours for quantification of the bone marrow neutrophil storage pool (NSP), neutrophil proliferative pool, granulocyte progenitors, and pluripotent progenitors. Functional activation of neutrophils (C3bi expression) was determined 24 hours after rhG-CSF or placebo administration. Intravenous rhG-CSF was not associated with any recognized acute toxicity. RhG-CSF induced a significant increase in the blood neutrophil concentration 24 hours after the 5 and 10 micrograms/kg doses every 12 and 24 hours and it was sustained as long as 96 hours. A dose-dependent increase in the NSP was seen following rhG-CSF. Neutrophil C3bi expression was significantly increased at 24 hours after 10 micrograms/kg every 24-hour dose of rhG- CSF. The half-life of rhG-CSF was 4.4 +/- 0.4 hours. The rhG-CSF was well tolerated at all gestational ages treated. The rhG-CSF induced a significant increase in the peripheral blood and bone marrow absolute neutrophil concentration and in C3bi expression. Future clinical trials aimed at improving the outcome of overwhelming bacterial sepsis and neutropenia in newborn infants might include the use of rhG-CSF.     

Blood mononuclear cells from patients with severe congenital neutropenia are capable of producing granulocyte colony-stimulating factor.

Severe congenital neutropenia (SCN) is a disorder of myelopoiesis characterized by severe neutropenia or absence of blood neutrophils secondary to a maturational arrest at the level of promyelocytes. We examined peripheral blood mononuclear cells (PBMC) of SCN patients who demonstrated normalization of their blood neutrophil counts in a phase II clinical study with recombinant human granulocyte colony-stimulating factor (rhG-CSF). When stimulated in vitro with bacterial lipopolysaccharides (LPS), PBMC of those SCN patients produced G-CSF activity, as judged by proliferation induction of the murine leukemia cell line, NFS-60. Western and Northern blot analysis showed G-CSF protein and G-CSF-mRNA indistinguishable in size from those of normal controls. We conclude that PBMC of the SCN patients tested are capable of synthesizing and secreting biologically active G-CSF in vitro.     

Changes in neutrophil counts and functions after the administration of recombinant human granulocyte colony-stimulating factor in a patient with chronic idiopathic neutropenia]

The cause of chronic idiopathic neutropenia (CIN) is unknown. Recently recombinant human granulocyte colony-stimulating factor (rhG-CSF) has been purified. Many studies of effects of rhG-CSF on the patients with neutropenia have been undertaken. We examined changes in neutrophil counts and functions after the administration of rhG-CSF in a patient with CIN. Six hours after the intravenous administration of 40 micrograms of rhG-CSF, neutrophil counts were raised from 90 to 1570/microliters, and the increased neutrophils functioned normally; chemotaxis, phagocytosis and O2(-) generation. It is suggested that rhG-CSF is beneficial for the treatment of infection in patients with CIN.     

In vivo administration of granulocyte colony-stimulating factor promotes neutrophil survival in vitro

Abstract: We recently showed that recombinant human granulocyte-colony stimulating factor (rhG-CSF) maintained the viability of human neutrophils in incubation for up to 72 hours. However, it is not known whether rhG-CSF can enhance neutrophil survival in in vivo situations. To clarify this issue, we investigated neutrophil survival in vitro following in vivo injection of rhG-CSF. Neutrophils were obtained from 4 pediatric patients with malignancies and healthy adult volunteers before and after rhG-CSF administration. Neutrophils obtained before rhG-CSF treatment started to undergo apoptosis after 24 h of incubation. In contrast, the survival of neutrophils drawn after rhG-CSF administration increased by approximately 24 h. Concomitantly, the appearance of typical ladder-like DNA fragmentation was delayed. Such an increase in neutrophil survival was inhibited by coincubation with either H 7 (10 μmol/1) or H 8 (20 μmol/1), which worked as protein kinase C inhibitors. Although our study did not measure neutrophil survival in vivo directly, it provides us with further evidence that rhG-CSF may function to prolong neutrophil life expectancy in vivo.     

Clinical effects of recombinant human granulocyte colony-stimulating factor in leukemia patients: a phase I/II study

A phase I/II study of recombinant human granulocyte colony-stimulating factor (rhG-CSF) in 24 leukemia patients was conducted at our institute. Recombinant human G-CSF (50-200 micrograms/m2/day) was administered i.v. In seven allogeneic bone marrow transplantation (BMT) recipients, treatment with rhG-CSF was started 5 days after BMT. Neutrophils began to increase within 3 days after the start of rhG-CSF administration in five of seven patients. The mean duration necessary for recovery of neutrophils to greater than 500/microliters was 11.3 days after BMT with rhG-CSF; 26.8 days is the figure for recovery without rhG-CSF from Japanese historical data. In seven out of eight patients who received rhG-CSF administration after the first remission-induction chemotherapy, the neutrophil counts increased from less than 300/microliters to greater than 4000/microliters within 10 days. Blasts did not increase in all patients including four acute nonlymphocytic leukemia (ANLL) patients. Severe infections such as septicemia and pneumonia, which were unable to be controlled by antibiotics only, were successfully treated with rhG-CSF and antibiotics. rhG-CSF either stimulated or inhibited myeloid leukemic cells in some refractory cases. Mild bone pain occurred in one patient while receiving rhG-CSF i.v. rhG-CSF seems to have the ability to shorten the period of neutropenia, prevent infections after allogeneic BMT and remission-induction chemotherapy for acute leukemia, and support therapy for infections.     

Effect of recombinant human granulocyte colony-stimulating factor on hematopoiesis in normal cats.

The objective of this study was to determine how recombinant human granulocyte colony-stimulating factor (rhG-CSF) affects hematopoiesis in normal cats. Recombinant human G-CSF was given at 3.0, 5.0, and 10.0 micrograms/kg to two cats each s.c. twice daily for 21 days. This resulted in significant (p less than 0.01) elevations of peripheral blood neutrophils from 3.0- to 9.2-fold above pretreatment levels and significantly (p less than 0.02) above levels of nontreated control cats (n = 4). A statistically significant dose-related response was not seen at these dosages in any parameter evaluated. The period of maximum neutrophilia occurred between days 10 and 14 of rhG-CSF treatment, with maximum neutrophil counts ranging from 20,370 cells/microliters to 61,400 cells/microliters (normal is less than 12,500). Lymphocytosis (greater than 7000 lymphocytes/microliters) and monocytosis (greater than 850 monocytes/microliters) were observed in 50% of the cats receiving rhG-CSF during the period of maximal neutrophil stimulation. Monocyte counts in treated cats were significantly (p less than 0.01) elevated over those of treatment controls on days 12-17. Lymphocyte numbers in rhG-CSF-treated cats were significantly elevated (p less than 0.05) over pretreatment controls on days 12 and 14 of rhG-CSF treatment. No significant changes were observed in reticulocyte counts, platelet counts, or hematocrit levels. By day 19, neutrophil levels had dropped significantly (p less than 0.01) from the maximum neutrophil levels, with one cat attaining a normal blood neutrophil count by day 21 of rhG-CSF treatment. Marrow aspirates revealed an overall increase in marrow cellularity through day 14 of treatment in rhG-CSF-treated cats, with increased myeloid:erythroid ratios (two- to ninefold) over those of nontreated controls. The erythroid and lymphoid component of the marrow decreased from day 0 to day 14, whereas the early myeloid progenitors (myeloblasts, progranulocytes, and myelocytes) increased significantly (p less than 0.05). No significant differences in the percentage of later myeloid forms in the marrow were observed over the treatment period. In vitro colony-forming assays of marrow obtained from treated cats revealed increases in granulocyte-macrophage colony-forming units (CFU-GM) through day 14, with subsequent decreases by day 21 of rhG-CSF treatment. Recombinant human G-CSF was also effective at in vitro stimulation of feline marrow cells from untreated cats in a dilution study, with maximal CFU-GM formation at 0.1 microgram rhG-CSF/ml assay.(ABSTRACT TRUNCATED AT 400 WORDS)     

A key role for G-CSF-induced neutrophil production and trafficking during inflammatory arthritis

We have previously shown that G-CSF-deficient (G-CSF(-/-)) mice are markedly protected from collagen-induced arthritis (CIA), which is the major murine model of rheumatoid arthritis, and now investigate the mechanisms by which G-CSF can promote inflammatory disease. Serum G-CSF levels were significantly elevated during CIA. Reciprocal bone marrow chimeras using G-CSF(-/-), G-CSFR(-/-), and wild-type (WT) mice identified nonhematopoietic cells as the major producers of G-CSF and hematopoietic cells as the major responders to G-CSF during CIA. Protection against CIA was associated with relative neutropenia. Depletion of neutrophils or blockade of the neutrophil adhesion molecule, Mac-1, dramatically attenuated the progression of established CIA in WT mice. Intravital microscopy of the microcirculation showed that both local and systemic administration of G-CSF significantly increased leukocyte trafficking into tissues in vivo. G-CSF-induced trafficking was Mac-1 dependent, and G-CSF up-regulated CD11b expression on neutrophils. Multiphoton microscopy of synovial vessels in the knee joint during CIA revealed significantly fewer adherent Gr-1(+) neutrophils in G-CSF(-/-) mice compared with WT mice. These data confirm a central proinflammatory role for G-CSF in the pathogenesis of inflammatory arthritis, which may be due to the promotion of neutrophil trafficking into inflamed joints, in addition to G-CSF-induced neutrophil production.     

G-CSF-mediated thrombopoietin release triggers neutrophil motility and mobilization from bone marrow via induction of Cxcr2 ligands

Emergency mobilization of neutrophil granulocytes (neutrophils) from the bone marrow (BM) is a key event of early cellular immunity. The hematopoietic cytokine granulocyte-colony stimulating factor (G-CSF) stimulates this process, but it is unknown how individual neutrophils respond in situ. We show by intravital 2-photon microscopy that a systemic dose of human clinical-grade G-CSF rapidly induces the motility and entry of neutrophils into blood vessels within the tibial BM of mice. Simultaneously, the neutrophil-attracting chemokine KC (Cxcl1) spikes in the blood. In mice lacking the KC receptor Cxcr2, G-CSF fails to mobilize neutrophils and antibody blockade of Cxcr2 inhibits the mobilization and induction of neutrophil motility in the BM. KC is expressed by megakaryocytes and endothelial cells in situ and is released in vitro by megakaryocytes isolated directly from BM. This production of KC is strongly increased by thrombopoietin (TPO). Systemic G-CSF rapidly induces the increased production of TPO in BM. Accordingly, a single injection of TPO mobilizes neutrophils with kinetics similar to G-CSF, and mice lacking the TPO receptor show impaired neutrophil mobilization after short-term G-CSF administration. Thus, a network of signaling molecules, chemokines, and cells controls neutrophil release from the BM, and their mobilization involves rapidly induced Cxcr2-mediated motility controlled by TPO as a pacemaker.     

Neutrophil kinetics shortly after initial administration of recombinant human granulocyte colony-stimulating factor: neutrophil alkaline phosphatase activity as an endogenous marker.

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) was administered (1.5 micrograms/kg body weight) subcutaneously once daily for 5 to 9 days to 5 patients with malignant lymphoma. In all patients, initial administration of rhG-CSF induced a rapid fall in the neutrophil count within 30 minutes, followed by a recovery and an increase in the neutrophil count within 150 min. A rapid fall in the neutrophil count was accompanied by increased expression of neutrophil C3bi-receptors, and neutrophils left in the circulation had lower activity of neutrophil alkaline phosphatase (NAP) and phagocytosis. A decrease in the NAP scores observed at 30 min reflected a preferential decrease of neutrophils with high NAP activity. A recovery and an increase in the neutrophil count were accompanied by a further decrease of NAP scores, which was caused by a preferential increase of neutrophils with lower NAP activity. The NAP scores of mature neutrophils from peripheral blood were not affected by in vitro treatment of cells with rhG-CSF for up to 150 min at 37 degrees C. These findings and the previous observations that neutrophils in the circulating and marginal pools have high NAP activity and neutrophils in the bone marrow pool have low NAP activity taken together suggest that, following initial administration of rhG-CSF, functionally active neutrophils leave the bloodstream preferentially, which is primarily followed by an influx of neutrophils from the bone marrow, but not by demargination of sequestered neutrophils.     

Increased granulopoiesis through interleukin-17 and granulocyte colony-stimulating factor in leukocyte adhesion molecule-deficient mice.

Many mutant mice deficient in leukocyte adhesion molecules display altered hematopoiesis and neutrophilia. This study investigated whether peripheral blood neutrophil concentrations in these mice are elevated as a result of accumulation of neutrophils in the circulation or altered hematopoiesis mediated by a disrupted regulatory feedback loop. Chimeric mice were generated by transplanting various ratios of CD18(+/+) and CD18(-/-) unfractionated bone marrow cells into lethally irradiated wild-type mice, resulting in approximately 0%, 10%, 50%, 90%, or 100% CD18 null neutrophils in the blood. The presence of only 10% CD18(+/+) neutrophils was sufficient to prevent the severe neutrophilia seen in mice reconstituted with CD18(-/-) bone marrow cells. These data show that the neutrophilia in CD18(-/-) mice is not caused by enhanced neutrophil survival or the inability of neutrophils to leave the vascular compartment. In CD18(-/-), CD18(-/-)E(-/-), CD18(-/-)P(-/-), EP(-/-), and EPI(-/-) mice, levels of granulocyte colony-stimulating factor (G-CSF) and interleukin-17 (IL-17) were elevated in proportion to the neutrophilia seen in these mice, regardless of the underlying mutation. Antibiotic treatment or the propensity to develop skin lesions did not correlate with neutrophil counts. Blocking IL-17 or G-CSF function in vivo significantly reduced neutrophil counts in severely neutrophilic mice by approximately 50% (P <.05) or 70% (P <.01), respectively. These data show that peripheral blood neutrophil numbers are regulated by a feedback loop involving G-CSF and IL-17 and that this feedback loop is disrupted when neutrophils cannot migrate into peripheral tissues.     

A comparison of treatment of canine cyclic hematopoiesis with recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF), G-CSF interleukin-3, and canine G-CSF.

Cyclic hematopoiesis in gray collie dogs is a stem cell disease in which abnormal regulation of cell production in the bone marrow causes cyclic fluctuations of blood cell counts. In vitro studies demonstrated that recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and granulocyte colony stimulating factor (G-CSF) all stimulated increases in colony formation by canine bone marrow progenitor cells. Based on these results, gray collie dogs were then treated with recombinant human (rh) GM-CSF, IL-3, or G-CSF subcutaneously to test the hypothesis that pharmacologic doses of one of these hematopoietic growth factors could alter cyclic production of cells. When recombinant canine G-CSF became available, it was tested over a range of doses. In vivo rhIL-3 had no effect on the recurrent neutropenia but was associated with eosinophilia, rhGM-CSF caused neutrophilia and eosinophilia but cycling of hematopoiesis persisted. However, rhG-CSF caused neutrophilia, prevented the recurrent neutropenia and, in the two animals not developing antibodies to rhG-CSF, obliterated periodic fluctuation of monocyte, eosinophil, reticulocyte, and platelet counts. Recombinant canine G-CSF increased the nadir neutrophil counts and amplitude of fluctuations at low doses (1 micrograms/kg/d) and eliminated all cycling of cell counts at high doses (5 and 10 micrograms/kg/d). These data suggest significant differences in the actions of these growth factors and imply a critical role for G-CSF in the homeostatic regulation of hematopoiesis.     

Actin polymerization in neutrophils from donors of peripheral blood stem cells: divergent effects of glycosylated and nonglycosylated recombinant human granulocyte colony-stimulating factor

Neutrophil functions can be modified by Recombinant human G-CSF (rhG-CSF) treatment, with divergent effects on phagocytosis, motility, bactericidal activity, and surface molecule expression. Neutrophil morphology is modified by treatment with filgrastim (the nonglycosylated form of rhG-CSF), while it is not affected by lenograstim (the glycosylated type of rhG-CSF). Little information is available about actin polymerization in neutrophils from subjects treated with the two types of rhG-CSF. In the current paper we evaluated two groups of donors of peripheral blood stem cells (PBSC) for allogeneic transplantation. Ten subjects were treated with filgrastim and 10 with lenograstim to mobilize PBSC; 15 blood donors were evaluated as a control group. Actin polymerization (both spontaneous and fMLP-stimulated) was studied by a flow cytometric assay. A microscopic fluorescent assay was also carried out to evaluate F-actin distribution in neutrophils. We found that filgrastim induced an increased F-actin content in resting neutrophils, along with morphologic evidence for increased actin polymerization distributed principally at the cell membrane and frequently polarized in focal areas; in addition, fMLP was not able to induce further actin polymerization. On the contrary, treatment with lenograstim was associated with F-actin content, distribution, and polymerization kinetics indistinguishable from those displayed by control neutrophils. Such experimental results show that filgrastim and lenograstim display divergent effects also on neutrophil actin polymerization and provide further explanation for previous experimental findings.