Purification and biochemical characterization of human pluripotent hematopoietic colony-stimulating factor

New agents for mobilizing peripheral blood stem cells

Transplantation with bone marrow (BM) hematopoietic stem cells (HSC) has been used for curative therapy of hematologic diseases and inborn errors of metabolism for decades. More recently, alternative sources of HSC, particularly those induced to exit marrow and traffic to peripheral blood in response to external stimuli, have become the most widely used hematopoietic graft and show significant superiority to marrow HSC. Although a variety of agents can mobilize stem cells with different kinetics and efficiencies and these agents can be additive or synergistic when used in combination, currently G-CSF is the predominant stem cell mobilizer used clinically based upon potency, predictability and safety. Recent studies have demonstrated that the interaction between the chemokine stromal-derived factor 1 (SDF-1/CXCL12) and its receptor CXCR4 serves as a key regulator of HSC trafficking. AMD3100, a novel bicyclam CXCR4 antagonist, induces the rapid mobilization of HSC with both short- and long-term repopulation capacity. Mobilization with G-CSF and AMD3100 in clinical trials resulted in more patients achieving sufficient PBSC for transplantation than with G-CSF alone. Thus, chemokine axis-mobilization could allow rapid PBSC harvests with increased cell yields in difficult-to mobilize patients. Studies of autologous and allogeneic transplantation of AMD3100 mobilized grafts demonstrated prompt and stable engraftment. Enhanced homing properties of chemokine axis-mobilized PBSC suggest that these cells may have greater therapeutic utility in other areas including tissue repair and regeneration.

Stem cell mobilisation for myocardial repair

BACKGROUND

The idea that autologous bone marrow derived stem cells (BMCs) can transdifferentiate into cardiomyocytes or vascular cells has been challenged in several scientific reports.

OBJECTIVE/METHODS

This review summarises conditions for stem cell mobilisation, their use for therapeutic approaches to prevent ischaemic cardiomyopathy after acute myocardial infarction and current clinical trials. Mechanisms for mobilisation and homing of BMCs are discussed.

RESULTS/CONCLUSIONS

The improvement in cardiac function after migration of autologous BMCs to the heart can be explained by their paracrine effects, inducing angiogenesis and preventing ischaemic myocardium from apoptosis. These effects may explain why the number of circulating BMCs is directly correlated with cardiovascular risk and life expectancy. Exercise and hormones are physiological stimuli for the mobilisation of BMCs, whereas cardiovascular risk factors severely reduce their number and functions. Current cardiovascular medications increase the amounts of autologous BMCs.

The impact of PEGylation on biological therapies

The term PEGylation describes the modification of biological molecules by covalent conjugation with polyethylene glycol (PEG), a non-toxic, non-immunogenic polymer, and is used as a strategy to overcome disadvantages associated with some biopharmaceuticals. PEGylation changes the physical and chemical properties of the biomedical molecule, such as its conformation, electrostatic binding, and hydrophobicity, and results in an improvement in the pharmacokinetic behavior of the drug. In general, PEGylation improves drug solubility and decreases immunogenicity. PEGylation also increases drug stability and the retention time of the conjugates in blood, and reduces proteolysis and renal excretion, thereby allowing a reduced dosing frequency. In order to benefit from these favorable pharmacokinetic consequences, a variety of therapeutic proteins, peptides, and antibody fragments, as well as small molecule drugs, have been PEGylated. This paper reviews the chemical procedures and the conditions that have been used thus far to achieve PEGylation of biomedical molecules. It also discusses the importance of structure and size of PEGs, as well as the behavior of linear and branched PEGs. A number of properties of the PEG polymer--e.g. mass, number of linking chains, the molecular site of PEG attachment--have been shown to affect the biological activity and bioavailability of the PEGylated product. Releasable PEGs have been designed to slowly release the native protein from the conjugates into the blood, aiming at avoiding any loss of efficacy that may occur with stable covalent PEGylation. Since the first PEGylated drug was developed in the 1970s, PEGylation of therapeutic proteins has significantly improved the treatment of several chronic diseases, including hepatitis C, leukemia, severe combined immunodeficiency disease, rheumatoid arthritis, and Crohn disease. The most important PEGylated drugs, including pegademase bovine, pegaspargase, pegfilgrastim, interferons, pegvisomant, pegaptanib, certolizumab pegol, and some of the PEGylated products presently in an advanced stage of development, such as PEG-uricase and PEGylated hemoglobin, are reviewed. The adaptations and applications of PEGylation will undoubtedly prove useful for the treatment of many previously difficult-to-treat conditions.

Recombinant human granulocyte colony-stimulating factor reduces colonic epithelial cell apoptosis and ameliorates murine dextran sulfate sodium-induced colitis

OBJECTIVE

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) is a potentially effective therapy for Crohn's disease. The purpose of this study was to test the rhG-CSF in murine dextran sulfate sodium-induced colitis (DSS colitis).

MATERIAL AND METHODS

Murine colitis was induced by feeding with water containing 3% DSS for 9 days. Six to 7-week-old female BALB/c mice were given rhG-CSF (100 microg/kg) or phosphate-buffered saline (PBS) subcutaneously once a day from day 0 to day 8, and the mice were sacrificed at days 3, 5, 7 and 9. Tissue specimens from the transverse colon, descending colon and rectum were obtained and stained with hematoxylin and eosin. Inflammation was scored for severity, extent, epithelial damage and crypt loss. TUNEL staining was performed to assess epithelial cell apoptosis.

RESULTS

Treatment with rhG-CSF significantly attenuated body-weight loss, stool score and shortening of the colon length in comparison with treatment with PBS (p<0.01,<0.05,<0.01, respectively). Histological scores for inflammation, epithelial cell damage and crypt loss of the rectum were less severe at day 9 in the rhG-CSF group than in the PBS group (p<0.01, 0.05, 0.01, respectively). The number of TUNEL-positive cells in the rectum was smaller in the rhG-CSF group than in the PBS group (p<0.001).

CONCLUSIONS

Treatment with rhG-CSF ameliorates murine DSS colitis by suppressing mucosal inflammation and epithelial damage in the rectum. The prevention of epithelial cell apoptosis seems to precede the anti-inflammatory action of rhG-CSF.

Early and late hemopoietic precursor cells in patients with chronic myeloproliferative diseases

We evaluated the content of early and late cobblestone area-forming cells, immediate progeny of hemopoietic stem cells, and committed precursor cells in the bone marrow and peripheral blood of patients with chronic myeloproliferative diseases and healthy donors. In patients with essential thrombocythemia, the number of late cobblestone area-forming cells in the peripheral blood decreased, while other parameters did not differ from those in healthy donors. In patients with idiopathic myelofibrosis, we found a decreased number of late and early cobblestone area-forming cells in the bone marrow and late cobblestone area-forming cells in the peripheral blood, while the count of early cobblestone area-forming cells in the peripheral blood increased. In patients with chronic myeloid leukemia, the number of early cobblestone area-forming cells in the bone marrow decreased, but the count of late and early cobblestone area-forming cells in the peripheral blood increased. The number of endogenous committed precursor cells in the peripheral blood increased in all groups of patients with chronic myeloproliferative diseases and, particularly, in patients with idiopathic myelofibrosis and chronic myeloid leukemia. Functional characteristics of immediate descendants of hemopoietic stem cells probably reflect the level of damage and attest to the existence of various mechanisms underlying the defect of the hemopoietic stem cell during chronic myeloproliferative diseases.

Meta-analysis of the efficacy of granulocyte-colony stimulating factor in animal models of focal cerebral ischemia

BACKGROUND AND PURPOSE

Recent reports have described the efficacy of the hematopoietic growth factor granulocyte-colony stimulating factor (G-CSF) in animal stroke models. Early clinical multicenter trials evaluating the effect of G-CSF in acute stroke and pilot clinical trials for the subacute phase are ongoing. To guide further development, a meta-analysis was performed to assess the effects of G-CSF on infarct size and sensorimotor deficits.

METHODS

Using electronic and manual searches of the literature, we identified studies describing the efficacy of G-CSF in animal models of focal cerebral ischemia. Two reviewers independently selected studies and extracted data on study quality, G-CSF doses, time of administration, and outcome measured as infarct volume and/or sensorimotor deficit. Data from all studies were pooled by meta-regression analyses.

RESULTS

Thirteen studies including 277 animals for infarct size calculation and 258 animals for assessment of sensorimotor deficit met the criteria for inclusion. Overall efficacy of G-CSF regarding infarct size reduction was 42%. Meta-regression analysis revealed a 0.8% (P<0.0001) decrease in infarct size per 1-mug/kg increase in G-CSF dose when applied within the first 6 hours and a 2.1% (P<0.0001) decrease when applied later than 6 hours after induction of ischemia with a significant (P=0.0004) greater infarct size reduction after delayed treatment. Sensorimotor deficits categorized into 3 subgroups improved between 24% and 40%.

CONCLUSIONS

Our findings consolidate G-CSF as a drug that both reduces infarct size and enhances functional recovery. These effects are presumably dose dependent. In contrast to most other neuroprotectants, a beneficial outcome may also be achieved when treatment is delayed.

The receptor for granulocyte-colony stimulating factor (G-CSF) is expressed in radial glia during development of the nervous system

Background

Granulocyte colony-stimulating (G-CSF) factor is a well-known hematopoietic growth factor stimulating the proliferation and differentiation of myeloid progenitors. Recently, we uncovered that G-CSF acts also as a neuronal growth factor in the brain, which promotes adult neural precursor differentiation and enhances regeneration of the brain after insults. In adults, the receptor for G-CSF is predominantly expressed in neurons in many brain areas. We also described expression in neurogenic regions of the adult brain, such as the subventricular zone and the subgranular layer of the dentate gyrus. In addition, we found close co-localization of the G-CSF receptor and its ligand G-CSF. Here we have conducted a systematic expression analysis of G-CSF receptor and its ligand in the developing embryo.

Results

Outside the central nervous system (CNS) we found G-CSF receptor expression in blood vessels, muscles and their respective precursors and neurons. The expression of the G-CSF receptor in the developing CNS was most prominent in radial glia cells.

Conclusion

Our data imply that in addition to the function of G-CSF and its receptor in adult neurogenesis, this system also has a role in embryonic neurogenesis and nervous system development.

Hematopoietic cytokines

The production of hematopoietic cells is under the tight control of a group of hematopoietic cytokines. Each cytokine has multiple actions mediated by receptors whose cytoplasmic domains contain specialized regions initiating the various responses-survival, proliferation, differentiation commitment, maturation, and functional activation. Individual cytokines can be lineage specific or can regulate cells in multiple lineages, and for some cell types, such as stem cells or megakaryocyte progenitors, the simultaneous action of multiple cytokines is required for proliferative responses. The same cytokines control basal and emergency hematopoietic cell proliferation. Three cytokines, erythropoietin, granulocyte colony-stimulating factor, and granulocyte-macrophage colony-stimulating factor, have now been in routine clinical use to stimulate cell production and in total have been used in the management of many millions of patients. In this little review, discussion will be restricted to those cytokines well established as influencing the production of hematopoietic cells and will exclude newer candidate regulators and those active on lymphoid cells. As requested, this account will describe the cytokines in a historical manner, using a sequential format of discovery, understanding, validation, and puzzlement, a sequence that reflects the evolving views on these cytokines over the past 50 years.

Hematopoietic growth factors for hematopoietic stem cell mobilization and expansion

During inflammation and cytopenia, increased levels of hematopoietic growth factors (HPGFs) induce mobilization and proliferation of hematopoietic stem cells and hematopoietic progenitor cells (HPCs), resulting in spatial and quantitative in vivo expansion of the hematopoietic tissue. Exogenous administration of recombinant HPGFs, particularly granulocyte colony-stimulating factor (G-CSF), is routine for mobilization of stem cells, followed by collection and transplantation of autologous or allogeneic stem cells. In this review, we summarize experience using different HPGFs and HPGF combinations for stem cell mobilization, such as G-CSF, granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), stem cell factor (SCF), and others. Preclinical and clinical studies of so-called early- and late-acting HPGFs for ex vivo expansion of HPCs are discussed, also with respect to the unresolved question whether expansion of repopulating stem cells can be achieved in vitro.

Cytokines and hematopoietic stem cell mobilization

Hematopoietic stem cell transplantation (HSCT) has become the standard of care for the treatment of many hematologic malignancies, chemotherapy sensitive relapsed acute leukemias or lymphomas, multiple myeloma; and for some non-malignant diseases such as aplastic anemia and immunodeficient states. The hematopoietic stem cell (HSC) resides in the bone marrow (BM). A number of chemokines and cytokines have been shown in vivo and in clinical trials to enhance trafficking of HSC into the peripheral blood. This process, termed stem cell mobilization, results in the collection of HSC via apheresis for both autologous and allogeneic transplantation. Enhanced understanding of HSC biology, processes involved in HSC microenvironmental interactions and the critical ligands, receptors and cellular proteases involved in HSC homing and mobilization, with an emphasis on G-CSF induced HSC mobilization, form the basis of this review. We will describe the key features and dynamic processes involved in HSC mobilization and focus on the key ligand-receptor pairs including CXCR4/SDF1, VLA4/VCAM1, CD62L/PSGL, CD44/HA, and Kit/KL. In addition we will describe food and drug administration (FDA) approved and agents currently in clinical development for enhancing HSC mobilization and transplantation outcomes.

Correlations between the activities of 19 anti-tumor agents and the intracellular glutathione concentrations in a panel of 14 human cancer cell lines: comparisons with the National Cancer Institute data

The aim of this work was 2-fold: (i) to identify correlations between the activities of pairs of 19 anti-tumor agents in a mini-panel of 14 human cancer cell lines of diverse origins with the goal of validating the panel, and (ii) to look for correlations between the activities of 19 standard anti-tumor agents and the intracellular concentrations of glutathione (GSH). Validation with analogous data from the National Cancer Institute (NCI) Developmental Therapeutics Program was made. The cell growth inhibition potencies of the anti-tumor agents [cisplatin, carboplatin, oxaliplatin, DACH-Pt, melphalan, chlorambucil, thiotepa, busulfan, doxorubicin, etoposide, camptothecin, vinblastine, podophyllotoxin, colchicine, taxol, hydroxyurea, methotrexate, 5-azacytidine and 5-fluorouracil (5-FU)] were estimated in 14 cancer cell lines by their GI50 values. An enzymatic assay based on the method of Tietze was employed to measure intracellular total GSH concentrations. The Delta method was used to compare pairs of anti-tumor agents; similarities and differences in activity profiles (mean graphs) were evaluated by regression analysis. Most, but not all, of the correlations could be explained based on similarities in the mechanisms of action and many correlations/non-correlations were also observed in the NCI data. Some correlations were unexpected however, and not seen in the NCI data. For example, strong positive correlations (P < 0.01) were found between the GI50 values of melphalan/chlorambucil and the anti-mitotic agents. Similarly unexpected, a strong positive correlation was observed between methotrexate and cisplatin (P < 0.01). Interestingly, moderate to strong negative correlations (P < 0.01-0.05) were found between the GI50 values of 5-FU and the anti-mitotic agents/melphalan/chlorambucil. Significant positive correlations between intracellular GSH concentrations and GI50 values were found only for thiotepa (P < 0.05) and doxorubicin (P < 0.01). Data from a NCI panel of 34 cancer cell lines showed no correlations between GSH levels and the GI50 values of the same 19 compounds. In conclusion, a panel of 14 human cancer cell lines of diverse origin was used to identify similarities and differences in the activities of standard anti-tumor agents. The level of significance was stronger with the 34 cell lines of the NCI, however. Our results indicate that GSH intracellular concentrations correlate with resistance only with doxorubicin and thiotepa in these cell lines.

An extended window of opportunity for G-CSF treatment in cerebral ischemia

Background

Granulocyte-colony stimulating factor (G-CSF) is known as a powerful regulator of white blood cell proliferation and differentiation in mammals. We, and others, have shown that G-CSF is effective in treating cerebral ischemia in rodents, both relating to infarct size as well as functional recovery. G-CSF and its receptor are expressed by neurons, and G-CSF regulates apoptosis and neurogenesis, providing a rational basis for its beneficial short- and long-term actions in ischemia. In addition, G-CSF may contribute to re-endothelialisation and arteriogenesis in the vasculature of the ischemic penumbra. In addition to these trophic effects, G-CSF is a potent neuroprotective factor reliably reducing infarct size in different stroke models.

Results

Here, we have further delayed treatment and studied effects of G-CSF on infarct volume in the middle cerebral artery occlusion (MCAO) model and functional outcome in the cortical photothrombotic model. In the MCAO model, we applied a single dose of 60 μg/kg bodyweight G-CSF in rats 4 h after onset of ischemia. Infarct volume was determined 24 h after onset of ischemia. In the rat photothrombotic model, we applied 10 μg/kg bodyweight G-CSF daily for a period of 10 days starting either 24 or 72 h after induction of ischemia. G-CSF both decreased acute infarct volume in the MCAO model, and improved recovery in the photothrombotic model at delayed timepoints.

Conclusion

These data further strengthen G-CSF's profile as a unique candidate stroke drug, and provide an experimental basis for application of G-CSF in the post-stroke recovery phase.

Protective effects of recombinant human granulocyte colony stimulating factor in a rat model of necrotizing enterocolitis

The role of cytokines and growth factors in the pathophysiology of neonatal necrotizing enterocolitis (NEC) is not defined clearly yet. The aim of this study was to determine the effects of recombinant human granulocyte colony stimulating factor (G-CSF) on intestinal cells in hypoxia-induced experimental NEC in rats. The study was experimented on Sprague Dawley rat pups. Group 1 (untreated, n = 7) rats were subjected to hypoxia-reoxygenation (H/O) and then were returned to standard conditions. Group 2 (G-CSF treated, n = 7) rats were subjected to H/O, and then were treated with G-CSF (100 microg/kg enterally) for 5 days. Group 3 was served as nonhypoxic controls. All animals were killed on day five, and histological examination was performed on intestinal samples. There were no histopathological changes in the control group. The histological findings in untreated rats were similar to those seen in neonatal NEC, with destruction of villi and crypts with extension to the muscularis layer. Intestinal damage was mild in group 2 and these histological changes were better than group 1, and worse than group 3. The mean of histologic grade of group 1 was 2.4 (range 2-3), and in the group 2, it was 1.2 (range 0-2). A difference was found when two groups were compared with each other (P < 0.05). In an experimental model of NEC, G-CSF could have a protective effect on intestinal damage.

Enteral granulocyte colony-stimulating factor for the treatment of mild (stage I) necrotizing enterocolitis: a placebo-controlled pilot study

BACKGROUND/PURPOSE

The presence of granulocyte colony-stimulating factor (G-CSF) in human milk and the expression of G-CSF receptors on intestinal villous enterocytes of neonates suggest that G-CSF has a role in the development and integrity of the gastrointestinal tract. We hypothesized that enteral recombinant human G-CSF (rhG-CSF) given to preterm infants with necrotizing enterocolitis (NEC) in the earlier stages could protect against disease progression and complications.

METHODS

Preterm infants with mild (stage I) NEC (n = 18) were assigned to receive enteral rhG-CSF (n = 8) or placebo (n = 10) for 5 days from the first day of the diagnosis. Clinical and gastrointestinal parameters were followed during the whole period of hospitalization.

RESULTS

In the study group, none of the infants with stage I NEC had a clinical progression to stage II or III, whereas in the control group, 5 (50%) infants with stage I NEC had a disease progression to stage II or III (P < .05). In the study group, the time required for the resolution of clinical and radiological findings of NEC and the total duration of systemic therapy and hospitalization were significantly shorter than the control group (P < .001).

CONCLUSION

Enteral rhG-CSF treatment could prevent the progression of mild (stage I) NEC to further stages and decrease the time required for the resolution of clinical and radiological signs of the disease.

Toward a Multimodal Neuroprotective Treatment of Stroke

Background and Purpose— Stroke remains a common medical problem with importance attributable to the demographic changes in industrialized societies.

Summary of Review— After years of setbacks, acute stroke therapy has finally emerged, including thrombolysis with tissue plasminogen activator (t-PA). However, t-PA treatment is limited by a narrow time window and side effects, so that only 3% of all stroke patients receive thrombolysis. Unimodal targeting of key events in stroke pathophysiology was not effective in providing long-term benefits, leading to negative results in previous clinical neuroprotective stroke trials. A successful future stroke therapy should approach multiple pathophysiological mechanisms besides revascularization at once, including reduction of t-PA–related side effects, prevention of cell death, stimulation of neuroregeneration, and plasticity.

Conclusions— Strategies targeting these processes include multiple combination therapies as well as treatment with multimodal drugs that interact with these mechanisms. Here, we review such combination approaches, and outline how this concept could be developed into future stroke treatment.

The cytokine-dependent MUTZ-3 cell line as an in vitro model for the screening of contact sensitizers

Langerhans cells (LC) are key mediators of contact allergenicity in the skin. However, no in vitro methods exist which are based on the activation process of LC to predict the sensitization potential of chemicals. In this study, we have evaluated the performances of MUTZ-3, a cytokine-dependent human monocytic cell line, in its response to sensitizers. First, we compared undifferentiated MUTZ-3 cells with several standard human cells such as THP-1, KG-1, HL-60, K-562, and U-937 in their response to the strong sensitizer DNCB and the irritant SDS by monitoring the expression levels of HLA-DR, CD54, and CD86 by flow cytometry. Only MUTZ-3 and THP-1 cells show a strong and specific response to sensitizer, while other cell lines showed very variable responses. Then, we tested MUTZ-3 cells against a wider panel of sensitizers and irritants on a broader spectrum of cell surface markers (HLA-DR, CD40, CD54, CD80, CD86, B7-H1, B7-H2, B7-DC). Of these markers, CD86 proved to be the most reliable since it detected all sensitizers, including benzocaine, a classical false negative in local lymph node assay (LLNA) but not irritants. We confirmed the MUTZ-3 response to DNCB by real-time PCR analysis. Taken together, our data suggest that undifferentiated MUTZ-3 cells may represent a valuable in vitro model for the screening of potential sensitizers.

Light-Activated Destruction of Cancer Cell Nuclei by Platinum Diazide Complexes

A possible way to avoid dose-limiting side effects of platinum anticancer drugs is to employ light to cause photochemical changes in nontoxic platinum prodrugs that release active antitumor agents. This strategy could be used in the treatment of localized cancers accessible to irradiation (e.g., bladder, lung, esophagus, and skin). We report here that nontoxic photolabile diam(m)ino platinum(IV) diazido complexes inhibit the growth of human bladder cancer cells upon irradiation with light, and are non-crossresistant to cisplatin. Their rate of photolysis closely parallels that of DNA platination, indicating that the photolysis products interact directly, and rapidly, with DNA. Photoactivation results in a dramatic shrinking of the cancer cells, loss of adhesion, packing of nuclear material, and eventual disintegration of their nuclei, indicating a different mechanism of action from cisplatin.

Development and validation of a sensitive ELISA for quantitation of Grastim® (rhG-CSF) in rat plasma: application to a pharmacokinetic study

Grastim is bacterially produced recombinant counterpart of human granulocyte colony stimulating factor (G-CSF). It has biological activity similar to that of endogenous G-CSF. In the present work a sensitive, accurate, precise and enzyme-linked immunosorbent assay (ELISA) for the quantitation of G-CSF in rat plasma was developed and validated. The ELISA method employed a technique in which anti-human-G-CSF was adsorbed onto 96-well maxisorp plates and used to capture the G-CSF in rat plasma samples. The captured G-CSF was then detected using streptavidin-HRP amplification system. Absolute recovery was >90% from rat plasma. The validation includes assessments of method accuracy and precision, range of reliable response, lower limit of quantitation (LLOQ), storage stability (30 days) in rat plasma and assay specificity. The standard curve for G-CSF was linear (R2 > 0.996) in the concentration range 4.88-625 pg/mL. The LLOQ was established at 4.88 pg/mL. The inter- and intra-day precisions in the measurement of quality control (QC) samples, 15, 250 and 500 pg/mL, were in the range 3.00-8.66% relative standard deviation (RSD) and 1.03-4.69% RSD, respectively. Accuracy in the measurement of QC samples was in the range 87.28-110.79% of the nominal values. The assay shows dilutional linearity and specificity. Stability of G-CSF was established for 30 days at -80 degrees C and through three freeze-thaw cycles. The validated assay was successfully employed for the assessment of pharmacokinetic disposition of G-CSF in rats.

Dysregulation of Expression of Immunoregulatory and Cytokine Genes and Its Association with the Immaturity in Neonatal Phagocytic and Cellular Immunity

BACKGROUND

Innate and adaptive immunity is comprised of cellular and humoral factors that provide rapid protection against microbial invasion. However, immaturity of innate and adaptive immune responses in the perinatal period predisposes the neonate to increased infectious morbidity and mortality from a variety of organisms.

OBJECTIVES

To elucidate dysregulation of expression of various immunoregulatory and cytokine genes and its association with the immaturity in neonatal phagocytic cellular immunity.

METHODS

Comparison of protein production and mRNA of granulocyte macrophage colony-stimulating factor (GM-CSF), macrophage colony-stimulating factor (M-CSF), granulocyte colony-stimulating factor (G-CSF), interleukin (IL)-12, IL-15 and IL-18 in adult peripheral blood (APB) mononuclear cells (MNC) and cord blood (CB) MNC was studied. Effects of hematopoietic growth factors (HGFs, GM-CSF, M-CSF, G-CSF, IL-11) were studied in vivo in rats as well as randomized controlled studies conducted in neonates. Oligonucleotide microarrays were used to study gene expression patterns of activated CB and APB monocytes and dendritic cells.

RESULTS AND CONCLUSIONS

We demonstrated dysregulation of various immunoregulatory and cytokine genes in CB MNC. This dysregulation may in part explain the immaturity of neonatal cell-mediated immunity. There are probably various dysregulated cytokines yet to be discovered. Biological agents such as IL-2, IL-12, IL-11 and/or IL-18 alone or in combination with HGFs should be considered for future studies to identify new approaches to enhance neonatal host defense, and thereby decrease the incidence of neonatal sepsis and the consequent high risk of morbidity and mortality.

A case of uterine cervical cancer presenting with granulocytosis

Granulocytosis occurs in 40% of patients with lung and gastrointestinal cancers, 20% of patients with breast cancer, 30% of patients with brain tumor and ovarian cancer and 10% of patients with renal cell carcinoma. Granulocytosis occurs because of production of G-CSF, GM-CSF and IL-6. Uterine cervical carcinoma with granulocytosis as a paraneoplastic syndrome, however, has been rarely reported. We recently witnessed a case of invasive squamous cell carcinoma of the uterine cervix with granulocytosis. Leukocytosis developed up to 69,000/microL, and then normalized after chemo-radiotherapy. There was no evidence of infection, tumor necrosis, glucocorticoid administration, or myeloproliferative disease by examination of a bone marrow aspirate when granulocytosis appeared. This phenomenon was probably associated with the secretion of hematopoietic growth factors such as G-CSF, GM-CSF and IL-6 by the tumor. We suggest that, like some other solid tumors, cervical cancer can present with granulocytosis as a paraneoplastic syndrome.

The hematopoietic factor G-CSF is a neuronal ligand that counteracts programmed cell death and drives neurogenesis

G-CSF is a potent hematopoietic factor that enhances survival and drives differentiation of myeloid lineage cells, resulting in the generation of neutrophilic granulocytes. Here, we show that G-CSF passes the intact blood-brain barrier and reduces infarct volume in 2 different rat models of acute stroke. G-CSF displays strong anti-apoptotic activity in mature neurons and activates multiple cell survival pathways. Both G-CSF and its receptor are widely expressed by neurons in the CNS, and their expression is induced by ischemia, which suggests an autocrine protective signaling mechanism. Surprisingly, the G-CSF receptor was also expressed by adult neural stem cells, and G-CSF induced neuronal differentiation in vitro. G-CSF markedly improved long-term behavioral outcome after cortical ischemia, while stimulating neural progenitor response in vivo, providing a link to functional recovery. Thus, G-CSF is an endogenous ligand in the CNS that has a dual activity beneficial both in counteracting acute neuronal degeneration and contributing to long-term plasticity after cerebral ischemia. We therefore propose G-CSF as a potential new drug for stroke and neurodegenerative diseases.

Reproducible preparation and effective separation of PEGylated recombinant human granulocyte colony-stimulating factor with novel “PEG-pellet” PEGylation mode and ion-exchange chromatography

A novel preparation for polyethylene glycol (PEG) derivatives and chromatographic separation procedure of the PEGylated recombinant human granulocyte colony-stimulating factor (rhG-CSF) were designed to evaluate the reproducibility and scalability at large laboratory-scale level. The new "PEG-pellet" PEGylation mode was successfully applied to control the pH fluctuation during the conjugation reaction, a general problem in traditional liquid-phase conjugation mode. Moreover, two consecutive ion-exchange chromatography steps were successfully used to separate and purify the PEGylated rhG-CSF. Cation-exchange chromatography was firstly applied to separate PEGylated rhG-CSF from intact rhG-CSF, followed by anion-exchange chromatography to obtain individual PEG-rhG-CSF species (mono-, di- and tri-PEGylated rhG-CSF) and remove the excess free PEG. Furthermore, the molecular weight of individual PEGylated rhG-CSF was identified by matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry and SDS-PAGE, and cell proliferation activity in vitro was detected by MTT assay using NFS-60 cell.

Converging pathways in leukemogenesis and stem cell self-renewal

Studies over the last 40 years have led to an understanding of the hierarchical organization of the hematopoietic system and the role of the pluripotential hematopoietic stem cell. Earlier recognition of the importance of bone marrow hematopoietic microenvironments has evolved into the recognition of specific niches that regulate stem cell pool size, proliferative status, mobilization, and differentiation. The discovery of the role of multiple hematopoietic growth factors and their receptors in the orchestration of stem cell self-renewal and differentiation has been followed by recognition of the importance of the Notch and Wnt pathways. The homeobox family of transcription factors serve as master regulators of development and are increasingly found to be critical regulators of hematopoiesis. In parallel with this understanding of normal hematopoiesis has come a recognition that stem cell dysregulation at various levels is involved in leukemogenesis. Furthermore, the progression from chronic leukemia or myelodysplasia to acute leukemia involves accumulation of at least two mutational events that lead to enhancement of stem cell proliferation, or acquisition of stem cell behavior by a progenitor cell, coupled with maturation inhibition. Translocations resulting in development of oncogenic fusion genes are found in AML and the transforming potential of two of these, AML1-ETO and NUP98-HOXA9, will be discussed. Secondary, constitutively activating mutations of the Flt3 and c-kit receptors and of K- and N-ras are found with high frequency in AML, and the transforming potential of mutated FLT3 and the role of STAT5A activation in human stem cell transformation will be reviewed.

The colony-stimulating factors: use to prevent and treat neutropenia and its complications

The colony-stimulating factors (CSFs) represent the only biological response modifiers used in clinical practice to treat or prevent neutropenia. These pleiotropic cytokines are available in clinical practice as granulocyte CSF (G-CSF), granulocyte-macrophage CSF (GM-CSF) and pegylated G-CSF. Neutropenia and its complications, most importantly febrile neutropenia (FN), remain major and serious side effects of cancer chemotherapy. Several studies and meta-analyses have addressed the clinical applications of CSFs to treat or prevent neutropenia. Guidelines have been developed to foster the appropriate use of CSFs. This article reviews the nature and use of the CSFs, and summarises the critical studies and guidelines. A historical perspective briefly describes the discovery, synthesis and clinical use of CSFs. The major biological and pharmacological characteristics are highlighted. The clinical applications of the CSFs are reviewed, including primary FN prophylaxis, secondary FN prophylaxis, treatment of FN, support of dose-dense chemotherapy regimens, use in leukaemia and myelodysplastic syndromes, utility in stem cell transplantation, and use in elderly and paediatric patients. Finally, clinical efficacy data, as well as the economic impact of the CSFs, are discussed.

Acute promyelocytic leukemia cell line AP-1060 established as a cytokine-dependent culture from a patient clinically resistant to all-trans retinoic acid and arsenic trioxide

AP-1060 is a newly established acute promyelocytic leukemia (APL) cell line from a multiple-relapse patient clinically resistant to both all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). The line was initially derived as a granulocyte colony-stimulating factor-dependent strain that underwent replicative senescence and, following ethylnitrosourea treatment, as a phenotypically similar immortalized line. Immortalization was associated with broadened cytokine sensitivity but not growth autonomy, in contrast to three previously derived APL lines. Both the AP-1060 strain and line had shortened telomeres and low telomerase activity, while the line had higher expression of many genes associated with macromolecular synthesis. The karyotype was 46,XY,t(3;14)(p21.1;q11.2),t(15;17)(q22;q11)[100%]; the unique t(3;14) was observed in 4/9 t(15;17)-positive metaphase cells at previous relapse on ATRA therapy. The PML-RARalpha mRNA harbored a missense mutation in the RARalpha-region ligand-binding domain (Pro900Ser). This was associated with a right-shift and sharpening of the ATRA-induced maturation response compared to ATRA-sensitive NB4 cells, which corresponded to the transcriptional activation by PML-RARalphaPro900Ser of a cotransfected ATRA-targeted reporter vector in COS-1 cells. AP-1060 also manifested relative resistance to ATO-induced apoptosis at >/=1 microM, while 0.25 microM ATO stimulated limited atypical maturation. These findings suggest that AP-1060 will be useful for further assessing molecular elements involved in APL progression and drug response/resistance.

Effect of serum deprivation on constitutive production of granulocyte-colony stimulating factor and granulocyte macrophage-colony stimulating factor in lung cancer cells

We previously established 2 lung cancer cell lines, OKa-C-1 and MI-4, which constitutively produce an abundant dose of granulocyte-colony stimulating factor (G-CSF) and granulocyte macrophage-colony stimulating factor (GM-CSF). Many other cases with G-CSF or GM-CSF producing tumors have been reported up to the present. However, the biological properties of the overproduction of G-CSF and GM-CSF by tumor cells have not been well known. Several reports demonstrated the presence of an autocrine growth loop for G-CSF and GM-CSF in nonhematopoietic tumor cells. We showed that exogenous G-CSF and GM-CSF stimulated cell growth in a dose-dependent manner in OKa-C-1 and MI-4 cells. We could detect the presence of G-CSF and GM-CSF receptors in both cell lines by RT-PCR analysis. We have previously shown that inflammatory cytokines, tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta enhance the expression of G-CSF and GM-CSF in the cell lines. However, the factors that regulate constitutive production of G-CSF or GM-CSF by tumor cells are still unknown well. In our study, we first reported that serum deprivation stimulated constitutive production of G-CSF and GM-CSF by lung tumor cells through activation of nuclear factor (NF)-kappaB and p44/42 mitogen-activated protein kinase (MAPK) pathway signaling. We suggest that G-CSF and GM-CSF constitutively produced by tumor cells could grow tumor itself and rescue tumor cells from the cytotoxicity of serum deprivation.

Continuous subcutaneous injection reduces polymorphonuclear leukocyte activation by granulocyte colony-stimulating factor

The use of granulocyte colony stimulating factor (G-CSF) for recovery from neutropenia has been established; however, acute lung injury due to G-CSF-induced polymorphonuclear leukocyte (PMN) activation is a serious complication. This study was designed to compare the activation of PMN with single bolus administration and continuous administration of G-CSF. Healthy volunteers (age 33.8 ± 1.4 yr; n = 6) received a single bolus injection of 50 μm/m2of G-CSF (SI; n = 6) or continuous subcutaneous injection of 50 μm/m2of G-CSF for 24 h (CI; n = 6) and were followed for 48 h. Circulating leukocyte counts, markers of activation on PMN, and circulating levels of G-CSF, IL-6, and PMN elastase were measured. SI rapidly increased serum G-CSF levels, which peaked at 4 h, whereas CI gradually increased G-CSF levels, which remained at a steady level from 8 to 24 h. SI caused a rapid decrease in PMN counts at 0.5 h followed by sustained increase to peak at 12 h. CI gradually increased PMN counts, which peaked at 24 h, but the peak values were not significantly different between the groups. SI-induced activation of PMN, which was characterized by increased expression of CD11b, decreased expression of L-selectin, and increased F-actin content, led to increases in serum IL-6 and PMN elastase level. Such changes were all attenuated with CI ( P < 0.05). We conclude that continuous subcutaneous injection of G-CSF resulted in a marrow response similar to that to a single injection but yielded reduced PMN activation.

Diagnostic and prognostic value of colony formation of hematopoietic progenitor cells in myeloid malignancies

Hematopoietic progenitor cells are capable of forming colonies of mature blood cells in semisolid media in response to specific growth factors. Colony assays have been extensively used for many years to study normal and malignant hematopoiesis in vitro. In fact, these assays have provided an excellent research tool for investigating growth and differentiation of progenitor cells in response to positive and negative regulators of hematopoiesis. However, apart from their role in basic research, colony assays are also widely used in routine clinical practice in the diagnosis of various hematologic disorders, such as aplastic anemia, myelodysplastic syndromes and myeloproliferative disorders. This review summarizes our current knowledge on the diagnostic value and prognostic significance of the growth of progenitor cells in peripheral blood and bone marrow in patients with myeloid malignancies.

Recombinant granulocyte colony-stimulating factor administered enterally to neonates is not absorbed

Granulocyte colony-stimulating factor (G-CSF) is present in liquids swallowed by the fetus and neonate; specifically, amniotic fluid, colostrum, and human milk. The swallowed G-CSF has local effects on enteric cells, which express the G-CSF receptor. However, some portion of the G-CSF ingested by the fetus and neonate might be absorbed into the circulation and have systemic actions, such as stimulating neutrophil production. To assess this possibility we sought to determine if circulating G-CSF concentrations of neonates increase after enteral administration of recombinant human granulocyte colony-stimulating factor (rhG-CSF). This was a single-center, prospective, blinded, randomized, 2 x 2 crossover study, with each infant receiving 1 dose of rhG-CSF (100 microg/kg) and 1 dose of placebo. Plasma G-CSF concentrations were measured at 2 and 4 hours after administration of the test solution. No significant change in plasma G-CSF concentration was observed after the enteral administration of rhG-CSF. On this basis, we conclude that orally administered rhG-CSF is not absorbed in significant quantities, and we speculate that the G-CSF swallowed by the fetus and neonate has local but not systemic effects.

In vivo processed fragments of IGF binding protein-2 copurified with bioactive IGF-II

Proteolysis of insulin-like growth factor binding proteins (IGFBPs), the major carrier of insulin-like growth factors (IGFs) in the circulation, is an essential mechanism to regulate the bioavailability and half-live of IGFs. Screening for peptides in human hemofiltrate, stimulating the survival of PC-12 cells, resulted in the isolation of C-terminal IGFBP-2 fragments and intact IGF-II co-eluting during the chromatographic purification procedure. The IGFBP-2 fragments exhibited molecular masses of 12.7 and 12.9kDa and started with Gly169 and Gly167, respectively. The fragments were able to bind both IGFs. The stimulatory effect of the purified fraction on the survival of the PC-12 cells could be assigned exclusively to IGF-II, since it was abolished by the addition of neutralizing IGF-II antibodies. We suggest that in the circulation IGF-II is not only complexed with intact IGFBP but also with processed IGFBP-2 fragments not impairing the biological activity of IGF-II.

PEGylation of G-CSF using cleavable oligo-lactic acid linkage

A new class of methoxy-poly(ethylene glycol) (mPEG) derivatives having a cleavable group of oligo-lactic acid (OLA) was synthesized by ring opening polymerization of L-lactide using a terminal hydroxyl end of mPEG as an initiator. The synthesized mPEG derivatives had 0.8 and 3.6 lactic acid units based on the MALDI-TOF data. A terminal end group of mPEG-OLA was further activated with p-nitrophenyl chloroformate to produce mPEG-OLA-p-nitrophenyl carbonate (PC). mPEG-OLA-PC derivatives were conjugated to primary amine groups of recombinant human granulocyte-colony stimulating factor. PEGylated G-CSF conjugated with mPEG-OLA-PC derivatives consisted of native, mono-, di-, and tri-PEGylated species, and they did not show any apparent conformational changes even after PEGylation. When incubating in pH 7.4 buffer at 37 degrees C for 2 days, mPEG-OLA-G-CSF conjugates liberated mPEG by cleaving the OLA spacer, resulting in the gradual regeneration of G-CSF.

Stem cell mobilization

Successful blood and marrow transplant (BMT), both autologous and allogeneic, requires the infusion of a sufficient number of hematopoietic progenitor/stem cells (HPCs) capable of homing to the marrow cavity and regenerating a full array of hematopoietic cell lineages in a timely fashion. At present, the most commonly used surrogate marker for HPCs is the cell surface marker CD34, identified in the clinical laboratory by flow cytometry. Clinical studies have shown that infusion of at least 2 x 10(6) CD34(+) cells/kg recipient body weight results in reliable engraftment as measured by recovery of adequate neutrophil and platelet counts approximately 14 days after transplant. Recruitment of HPCs from the marrow into the blood is termed mobilization, or, more commonly, stem cell mobilization. In Section I, Dr. Tsvee Lapidot and colleagues review the wide range of factors influencing stem cell mobilization. Our current understanding focuses on chemokines, proteolytic enzymes, adhesion molecules, cytokines and stromal cell-stem cell interactions. On the basis of this understanding, new approaches to mobilization have been designed and are now starting to undergo clinical testing. In Section II, Dr. Michele Cottler-Fox describes factors predicting the ability to mobilize the older patient with myeloma. In addition, clinical approaches to improving collection by individualizing the timing of apheresis and adjusting the volume of blood processed to achieve a desired product are discussed. Key to this process is the daily enumeration of blood CD34(+) cells. Newer methods of enumerating and mobilizing autologous blood HPCs are discussed. In Section III, Dr. John DiPersio and colleagues provide data on clinical results of mobilizing allogeneic donors with G-CSF, GM-CSF and the combination of both as relates to the number and type of cells collected by apheresis. Newer methods of stem cell mobilization as well as the relationship of graft composition on immune reconstitution and GVHD are discussed.

Induction and regulation of endogenous granulocyte colony-stimulating factor formation

Granulocyte colony-stimulating factor (G-CSF) is one of the most prominent endogenous proteins in broad clinical use. While its biological and clinical effects are relatively well studied, little is known about its endogenous formation in health and disease. However, such knowledge is crucial to decide in which situations G-CSF should be applied efficiently in the clinic, ie. when endogenous production does not suffice. The dramatic changes induced by G-CSF in the differential blood cell count are directly immunomodulatory, strengthening the innate defence by multiplying neutrophilic granulocytes. A multitude of further immunomodulatory effects contribute to the regulation of the concerted host defence. In this review, following a short introduction into the biology of G-CSF, the available data on endogenous formation in a number of animal models and human diseases is compiled. The cellular sources and inducers of G-CSF formation are reviewed and the regulation of G-CSF expression on both the transcriptional and translational level are discussed. The emerging understanding of the role and regulation of endogenous G-CSF formation opens up possibilities to define therapeutic windows as well as targets for diagnostics or drug development. Lastly, the modulation of G-CSF formation by various pharmacological agents alerts to putative side effects of these drug treatments.

Prospective randomized trial between two doses of granulocyte colony-stimulating factor after ifosfamide, carboplatin, and etoposide in children with recurrent or refractory solid tumors: a children's cancer group report

PURPOSE

The objectives of this study were: 1) to compare the time to hematologic recovery (absolute neutrophil count [ANC] > or = 1,000/mm3 and platelet count > or = 100,000/mm3) in a randomized prospective study of two doses of granulocyte colony-stimulating factor (G-CSF) (5.0 vs. 10.0 microg/kg per day) after ifosfamide, carboplatin, and etoposide (ICE) chemotherapy; and 2) to determine the response rate (complete response [CR] + partial response [PR]) of ICE in children with refractory or recurrent solid tumors.

PATIENTS AND METHODS

From June 1992 until November 1994, 123 patients with recurrent or refractory pediatric solid tumors were treated with ifosfamide (1,800 mg/m2 per day x 5), carboplatin (400 mg/m2 per day x 2), and etoposide (100 mg/m2 per day x 5) and randomized to receive either 5.0 microg/kg per day or 10.0 microg/kg per day of G-CSF subcutaneously until recovery of ANC to > or = 1,000/mm3.

RESULTS

The incidence of grade 4 neutropenia during the first course was 88%. Median time from the start of chemotherapy to ANC > or = 1,000/mm(-3) for all patients during courses 1 and 2 was 21 and 19 days, respectively. The incidence of developing platelet count < or = 20,000/mm3 during course 1 was 82%. The median time from the start of the course of chemotherapy to platelet recovery > or =100,000/mm3 for all patients during courses 1 and 2 was 27 days. There was no significant difference in the median time of ANC recovery, platelet recovery, or incidence of grade 4 neutropenia; and in the median days of fever and the incidence of infections requiring hospitalization and intravenous antibiotics during courses 1 and 2, there was no significant difference between the two doses of G-CSF. One hundred eighteen patients were evaluated for response to ICE. The overall response rate (CR + PR) in this study was 51% (90% confidence interval, 43%-59%). The CR rate for all diagnostic categories was 27%. The Kaplan-Meier estimates of 1-year and 2-year survival probabilities for all patients were 52% and 30%, respectively.

CONCLUSION

In summary, this combination of chemotherapy (ICE) was associated with a high CR rate (27%) in children with recurrent or refractory solid tumors, but also with a high incidence of grade 4 neutropenia and thrombocytopenia. Doubling the dose of G-CSF from 5.0 to 10.0 microg/kg per day after ICE chemotherapy did not result in an enhancement of neutrophil or platelet recovery or the incidence of grade 4 neutropenia developing.

A case of cervical cancer with aggressive tumor growth: possible autocrine growth stimulation by G-CSF and Il-6

BACKGROUND

Patients with tumors that produce hematopoietic growth factors, such as G-CSF, sometimes exhibit leukemoid reactions. Squamous cell carcinomas of the uterine cervix producing such factors are rarely reported.

CASE

A 56-year-old woman had severe leukocytosis (>50 x 10(3)/microl) and fever without evidence of infection after radical hysterectomy for treatment of her cervical cancer. The parametrial recurrent mass appeared after the operation and exhibited extremely aggressive growth. Serum levels of G-CSF and IL-6 were extremely high, and immunohistochemical analysis and RT-PCR assays revealed that G-CSF and IL-6 as well as their receptors were produced in tumor cells.

CONCLUSIONS

This is a case of cervical cancer which exhibited an aggressive clinical course, possibly due to autocrine stimulation of cell growth by G-CSF and IL-6.

A practical approach to evaluating and treating neutropenia in the neonatal intensive care unit

Neutropenia is a relatively common problem in the NICU, recognized in as many as 8% of patients at some time during their hospital stay. In most instances, neutropenia among NICU patients is of short duration and has little influence on outcome. In other cases it is prolonged and severe, and constitutes a serious antimicrobial defense deficiency. When a neonatologist discovers a low blood neutrophil count, choices must be made regarding further evaluation and treatment. The authors hope that the information provided in this article is useful in making these choices.

Human developmental biology of granulocyte colony-stimulating factor

The availability of granulocyte colony-stimulating factor (G-CSF) has influenced the management of neonates with neutropenia. Since the first use of G-CSF in a neonate with neutropenia, much has been learned about the cellular sources and physiologic roles of G-CSF. This article reviews our present understanding of G-CSF and its cognate receptor in the fetus and neonate.

Exclusive expression of G-CSF receptor on myeloid progenitors in bone marrow CD34+ cells

Although granulocyte colony-stimulating factor (G-CSF) has been reported to act on cells of neutrophilic lineage, the administration of G-CSF to induce the mobilization of various haematopoietic progenitors into the circulation. We analysed the expression of receptors for G-CSF (G-CSFR) on human bone marrow and G-CSF-mobilized peripheral blood CD34+ cells, and examined the proliferation and differentiation capabilities of sorted CD34+G-CSFR+ and CD34+G-CSFR- cells using methylcellulose clonal culture. Flow cytometric analysis showed that G-CSFR was expressed on 14.9 +/- 4.9% of bone marrow CD34+ cells, most of which were included in CD34+CD33+ and CD34+CD38+ cell fractions. In clonal cultures, CD34+G-CSFR+ cells produced only myeloid colonies, whereas CD34+G-CSFR- cells produced erythroid bursts, megakaryocyte and multilineage colonies. When incubated with the cytokine cocktail for 5 d, CD34+G-CSFR- cells generated CD34+G-CSFR+ myeloid progenitors. In G-CSF-mobilized peripheral blood, CD34+ cells contained 10.8 +/- 5.8% of G-CSFR+ cells, most of which were also myeloid progenitors, although CD34+G-CSFR- cells contained a substantial number of myeloid progenitors. These results indicated that the expression of G-CSFR on CD34+ cells is restricted to myeloid progenitors, suggesting that the specific activity of G-CSF on myelopoiesis depends on the exclusive expression of its receptor on myeloid progenitors, and that the mobilization of various haematopoietic progenitors is not a direct effect of G-CSF in humans.

Extended activity in cynomolgus monkeys of a granulocyte colony-stimulating factor mutein conjugated with high molecular weight polyethylene glycol

The activity of a granulocyte colony-stimulating factor (G-CSF) mutein (nartograstim; [NTG]) conjugated with an average of two polyethylene glycol (PEG) chains per protein molecule was examined in cynomolgus monkeys following a single s.c. injection. Groups of monkeys were given 10 microg/kg, 30 microg/kg, or 100 microg/kg. For comparison, one group of monkeys was given 5 microg/kg of recombinant human G-CSF (rHuG-CSF) daily for six days. In monkeys given 100 microg/kg of PEG-NTG, neutrophil levels reached a peak one day after injection approximately 20-fold higher than baseline levels. Neutrophil numbers in these animals were still significantly elevated six days after injection. In contrast, peak neutrophil levels in monkeys given six injections of rHuG-CSF reached a peak only on day 6 and were approximately the same as that in monkeys given a single dose of PEG-NTG six days before. Pharmacokinetics of PEG-NTG in these monkeys indicated that the area under the plasma concentration time curve (AUC) increased with increasing the dose from 497 ng x h/ml at 10 microg/kg, 6,140 ng x h/ml at 30 microg/kg to 27,900 ng x h/ml at 100 microg/kg. In a separate study, the effects of single doses of 100 microg/kg of PEG-NTG, rHuG-CSF, and unmodified NTG were compared. In this experiment, peak numbers of neutrophils were reached two days after injection in animals receiving PEG-NTG and one day after in animals given unmodified proteins. The pharmacokinetic parameters demonstrated increased exposure for PEG-NTG relative to the unmodified proteins with an AUC0. of 21,012 ng x h/ml compared with 5,492 ng x h/ml for rHuG-CSF and 5,153 ng x h/ml for NTG. These results demonstrate that conjugation of a G-CSF mutein with high molecular weight PEG results in a preparation that can induce prolonged elevation of neutrophils in normal nonhuman primates following a single injection.