Granulocyte-macrophage colony-stimulating factor enhances neutrophil function in acquired immunodeficiency syndrome patients

Defining the role of neutrophils in the lung during infection: Implications for tuberculosis disease

Neutrophils are implicated in the pathogenesis of many diseases involving inflammation. Neutrophils are also critical to host defence and have a key role in the innate immune response to infection. Despite their efficiencies against a wide range of pathogens however, their ability to contain and combat Mycobacterium tuberculosis (Mtb) in the lung remains uncertain and contentious. The host response to Mtb infection is very complex, involving the secretion of various cytokines and chemokines from a wide variety of immune cells, including neutrophils, macrophages, monocytes, T cells, B cells, NK cells and dendritic cells. Considering the contributing role neutrophils play in the advancement of many diseases, understanding how an inflammatory microenvironment affects neutrophils, and how neutrophils interact with other immune cells, particularly in the context of the infected lung, may aid the design of immunomodulatory therapies. In the current review, we provide a brief overview of the mechanisms that underpin pathogen clearance by neutrophils and discuss their role in the context of Mtb and non-Mtb infection. Next, we examine the current evidence demonstrating how neutrophils interact with a range of human and non-human immune cells and how these interactions can differentially prime, activate and alter a repertoire of neutrophil effector functions. Furthermore, we discuss the metabolic pathways employed by neutrophils in modulating their response to activation, pathogen stimulation and infection. To conclude, we highlight knowledge gaps in the field and discuss plausible novel drug treatments that target host neutrophil metabolism and function which could hold therapeutic potential for people suffering from respiratory infections.

Priming of the neutrophil respiratory burst: role in host defense and inflammation

Neutrophils are the major circulating white blood cells in humans. They play an essential role in host defense against pathogens. In healthy individuals, circulating neutrophils are in a dormant state with very low efficiency of capture and arrest on the quiescent endothelium. Upon infection and subsequent release of pro-inflammatory mediators, the vascular endothelium signals to circulating neutrophils to roll, adhere, and cross the endothelial barrier. Neutrophils migrate toward the infection site along a gradient of chemo-attractants, then recognize and engulf the pathogen. To kill this pathogen entrapped inside the vacuole, neutrophils produce and release high quantities of antibacterial peptides, proteases, and reactive oxygen species (ROS). The robust ROS production is also called 'the respiratory burst', and the NADPH oxidase or NOX2 is the enzyme responsible for the production of superoxide anion, leading to other ROS. In vitro, several soluble and particulate agonists induce neutrophil ROS production. This process can be enhanced by prior neutrophil treatment with 'priming' agents, which alone do not induce a respiratory burst. In this review, we will describe the priming process and discuss the beneficial role of controlled neutrophil priming in host defense and the detrimental effect of excessive neutrophil priming in inflammatory diseases.

Haematological manifestations of human immune deficiency virus infection

Early in the human immunodeficiency virus (HIV) epidemic, infected patients presented to medical attention with striking abnormalities in each of the major blood cell lineages. The reasons for these derangements remain complex and multifactorial. HIV infects multipotent haematopoietic progenitor cells and establish latent cellular reservoirs, disturbs the bone marrow microenvironment and also causes immune dysregulation. These events lead to cytokine imbalances and disruption of other factors required for normal haematopoiesis. Activation of the reticulo-endothelial system can also result in increased blood cell destruction. The deleterious effects of medications, including first and second generation anti-retroviral agents, on haematopoiesis were well documented in the early years of HIV care; in the current era of HIV-care, the advent of newer and less toxic anti-retroviral drugs have had a more beneficial impact on haematopoiesis. Due to impaired regulation of the immune system and potential side effects of one or more anti-retroviral agents, there is also an increase in coagulation abnormalities such as thromboembolism, and less frequently, acquired disorders of coagulation including thrombotic thrombocytopenic purpura, immune thrombocytopenic purpura and acquired inhibitors of coagulation. In this article we review the epidemiology and aetiology of select non-oncological haematological disorders commonly seen in people living with HIV-acquired immune deficiency syndrome.

Abnormalities in host defense associated with HIV infection

The broad variety of pulmonary infections encountered in human immunodeficiency virus (HIV)-infected individuals demonstrates that the host defense network is impaired. An improved understanding of these events in the lung can lead to specific interventions aimed at restoration of deficient function. This review summarizes the pulmonary host defense deficits in HIV-infected individuals, focusing on lymphocytes, alveolar macrophages, and neutrophils.

The human immunoglobulin A Fc receptor FcαRI: a multifaceted regulator of mucosal immunity

Immunoglobulin A (IgA) is commonly recognized as the most prevalent antibody (Ab) at mucosal sites with an important role in defense by shielding mucosal surfaces from invasion by pathogens. However, its potential to both actively dampen excessive immune responses or to initiate potent proinflammatory cellular processes is less well known. Interestingly, either functional outcome is mediated through interaction with the myeloid IgA Fc receptor FcαRI (CD89). Monomeric interaction of IgA with FcαRI triggers inhibitory signals that block activation via other receptors, whereas multimeric FcαRI crosslinking induces phagocytosis, reactive oxygen species production, antigen presentation, Ab-dependent cellular cytotoxicity, and cytokine release. Thus, FcαRI acts as a regulator between anti- and proinflammatory responses of IgA. As such, the biology of FcαRI, and its multifaceted role in immunity will be the focus of this review.

Immunoglobulin A: A next generation of therapeutic antibodies?

Although immunoglobulin (Ig) A is commonly recognized as the most prevalent antibody subclass at mucosal sites with an important role in mucosal defense, its potential as a therapeutic monoclonal antibody is less well known. However, IgA has multifaceted anti-, non-, and pro-inflammatory functions that can be exploited for different immunotherapeutical strategies, which will be the focus of this review.

The molecular regulators of macrophage and granulocyte development. Role of MGI-2/IL-6

The development of a cell culture system for the in vitro cloning and clonal differentiation of normal hematopoietic cells made it possible to identify the proteins that regulate growth and differentiation of different hematopoietic cell lineages and the change in normal controls that produce leukemia. A model system with myeloid cells has identified different myeloid cell colony-inducing proteins, which we called MGI-1 (= CSF, including IL-3). There is another protein that we first described in 1976 and called MGI-2 in 1980 that induces differentiation of myeloid cells to macrophages or granulocytes without inducing the clonal growth of myeloid cells. The four CSF proteins and IL-1 induce the production of MGI-2 in myeloid cells and MGI-2 induces the production of GM-CSF. This shows the participation of MGI-2 in the network of interactions with different myeloid regulatory proteins. Using a monoclonal antibody to MGI-2, amino acid sequencing, and recombinant protein, we have shown in collaboration with the Genetics Institute that the major form of MGI-2 (MGI-2A) is IL-6. This shows that IL-6 is a myeloid cell differentiation inducing protein. The results also suggest new clinical potentials for MGI-2/IL-6.

Responses of neutrophils to myeloid growth factors

Colony-stimulating factors (CSFs) have important effects on mature myeloid cells in addition to their regulatory role in haemopoiesis. Exposure of neutrophils to granulocyte macrophage-CSF (GM-CSF) increases chemotaxis, phagocytosis and cytotoxicity and primes the cells for enhanced oxidative metabolism in response to stimuli, such as formylated oligopeptides derived from bacteria (f-Met-Leu-Phe) and endogenous activated complement components (C5a). GM-CSF induces time-dependent changes in neutrophil f-Met-Leu-Phe receptor number and affinity that correspond to changes in functional activity. The neutrophil IgA Fc receptor is also modulated by GM-CSF such that it develops a high affinity state and transduces a phagocytic signal. The ability to regulate the number and activity of mature myeloid effector cells in vivo establishes unique therapeutic opportunities in the area of infectious disease, cancer treatment, bone marrow transplantation and augmentation of host defence in immunodeficient patients.

Effects of syngeneic cellular vaccinations alone or in combination with GM-CSF on the weakly immunogenic F98 glioma model

Cancer vaccines are one approach for the treatment of brain tumors. Most experimental studies are performed on so-called "immunogenic" brain tumor models such as the rat 9L glioma which does not reflect characteristics of human glioblastoma. In the present study, we tested syngeneic cellular vaccinations alone or in combination with granulocyte-macrophage colony-stimulating factor (GM-CSF) on the weakly immunogenic F98 glioma model. Previous studies have shown the efficacy of this treatment on the 9L glioma model. Fisher rats received an intracerebral implantation of F98 cells. Three days later, two subcutaneous vaccinations with irradiated F98 cells were realized in presence or absence of GM-CSF. This scheme of vaccination induced a systemic cellular and humoral immune response capable of in vitro cytolytic activity against F98 cells. However, no significant differences in survival times were noted between vaccinated and untreated animals. Animals vaccinated with GM-CSF or without GM-CSF had respectively a survival time of 26 +/- 2.1 and 25 +/- 4.4 days following tumor challenge versus 26.5 +/- 2.4 days for untreated rats. Fourteen days after the intracerebral tumor implantation, the tumors of vaccinated animals showed a robust infiltration by T lymphocytes, NK cells, dendritic cells, granulocytes and CD11b/c+ myeloid cells. This infiltration was nearly absent in untreated animals except for CD11b/c+ myeloid cells. This study shows that, contrary to the 9L glioma model, the F98 glioma model is resistant to syngeneic cellular vaccinations although a strong peripheral and intratumoral immune response can be induced. These results suggest that the F98 glioma is an attractive model to understand the mechanisms of glioma immunotherapy resistance.

The immunocompromised host: HIV infection

The variety of pulmonary infections encountered in HIV-infected individuals indicates that many components of the host defense network are impaired. In addition to depletion of CD4+ T cell numbers, HIV infection results in functional deficits in CD4+ T cells, CD8+ T cells, and natural killer cells. Although some components of macrophage defense are preserved, lack of activation signals from CD4+ T cells contributes to impaired defense by macrophages. There are few data examining the functional capabilities of neutrophils in the lung, but evidence from peripheral blood neutrophils indicates that defense by these cells is also impaired. An improved understanding of these events in the lung during HIV infection could lead to specific interventions aimed at restoration of deficient function.

Identification of an Antigenic Domain Near the C Terminus of Human Granulocyte-Macrophage Colony-stimulating Factor and Its Spatial Localization

The goal of this study was to map an epitope on the human granulocyte-macrophage colony-stimulating factor (hGM-CSF) at its C terminus, a region whose integrity is fundamental in maintaining the normal function of this molecule. Residues including the fourth alpha-helix (D, 103-116) were analyzed for their role in the interaction with antibodies (Abs) raised against the protein. Five peptides homologous to different segments of the C terminus of hGM-CSF were synthesized. Peptide-(102-121) included the same residues of the alpha-helix D and the next five amino acids toward the C terminus; peptide-[E108A]-(102-121) introduced the mutation E108A in order to verify the role of acidic residues; peptide-[C96A](93-110) encompassed the beta-sheet 2 and half of the alpha-helix D; peptide-[C121A]-(110-127) included the second half of the alpha-helix D and the C terminus of hGMCSF; peptide-(13-31)-Gly-Pro-Gly-(103-116) included both the alpha-helices A and D connected by the tripeptide Gly-Pro-Gly, which allows the original antiparallel orientation of the two alpha-helices to be maintained. Both anti-protein and anti-peptide-(102-121) antibodies, capable of neutralizing the stimulatory activity of hGMCSF in the bone marrow colony-forming assays, recognized a specific epitope in the C terminus of hGM-CSF. Molecular modeling estimated the surface accessibility of hGM-CSF and the stability of the synthetic peptides in aqueous solution. Altogether, our results showed that the immunogenic region includes part of the alpha-helix D and the residues 116-120, which are external to this helix and particularly exposed on the protein surface, confirming the feasible participation of this region in antibody binding.

The use of growth factors and cytokines to treat opportunistic infections in HIV-1 disease

The success of highly active antiretroviral therapy (HAART) in reducing AIDS-related mortality means that in regions where HAART is available, HIV infection may now be regarded as a chronic disease. However the inability of HAART to eliminate HIV-1 from various anatomical and cellular reservoirs within the body means that HIV-infected individuals require life-long treatment with therapy that can have significant side effects. Management of HIV disease is therefore increasingly focused on drug-related toxicities and the improvement of current HAART regimens. Here we review the potential use of immunomodulatory cytokines to directly or indirectly stimulate the mononuclear phagocyte system as adjuncts to current HIV treatment as well as their use in the management of opportunistic infections in individuals who develop immunodeficiency. We argue that cytokines, which stimulate mononuclear phagocyte activity against opportunistic pathogens, may be useful for the treatment of individuals who develop recurrent opportunistic infections. Cytokines may act synergistically with antimicrobial agents to improve outcomes, which is of particular importance since recurrent infections frequently result in resistance to standard antimicrobial treatments. Before their use can be advocated however, given their toxicity and significant cost, the potential benefits of cytokines must be demonstrated in larger clinical trials.

Granulocyte-macrophage colony-stimulating factor gene-transduced tumor cells combined with tumor-derived gp96 inhibit tumor growth in mice

Granulocyte-macrophage colony-stimulating factor (GM-CSF)-based cancer cell vaccines have been shown to be potent inducers of antitumor immunity in several murine models, but the antitumor effects on established tumors have been minimal. Conversely, the major role of the heat shock protein gp96, localized in the endoplasmic reticulum (ER), is to act as a molecular chaperone to assist the folding of nascent polypeptide chains in the ER. gp96 derived from tumor cells elicits specific protective immunity against parental tumors, presumably through the transport of tumor-specific peptides to antigen-presenting cells and the maturation of dendritic cells (DCs). However, the therapeutic effects of tumor-derived gp96 on established tumors have not been promising. The present study analyzes the therapeutic effects of GM-CSF gene-transduced Lewis lung cancer (LLC/GM) cells combined with LLC-derived gp96 on established wild-type LLC tumors in immunocompetent C57BL/6 mice. Therapy with either irradiated LLC/GM cells or LLC-derived gp96 barely affected established LLC tumor growth. The antitumor effect was significantly enhanced when 1 microg of LLC-derived gp96 was administered together with 1 x 10(6) irradiated LLC/GM cells (p < 0.05). The antitumor effects of irradiated LLC/GM cells and LLC-derived gp96 required mainly CD8(+) T cells. Spleen cells obtained from mice vaccinated with irradiated LLC/GM cells and LLC-derived gp96 showed specific CD8 cytotoxic activities against LLC cells (specific lysis rate of approximately 28%). This antibody response was not associated with a synergic effect of the combination therapy. Moreover, draining lymph nodes from mice immunized with irradiated LLC/GM cells and LLC-derived gp96 contained more migrating mature CD11c(+) cells (higher levels of CD86 and major histocompatibility complex [MHC] class II molecules) compared with those from any other immunization protocols. These results suggest that the combination of irradiated LLC/GM cells and tumor-derived gp96 has potential as a new immunogene therapeutic strategy against lung cancer.

Capacity of neutrophils and monocytes from human immunodeficiency virus-infected patients and healthy controls to inhibit growth of Mycobacterium bovis

We compared the differences in growth inhibition of Mycobacterium bovis by monocytes and neutrophils from human immunodeficiency virus (HIV)-infected persons (n = 12; mean CD4 count = 451/mm(3)) and healthy controls (n = 6). Phagocytes from all HIV-infected patients were incubated with or without exogenous granulocyte-macrophate colony-stimulating factor (GMCSF; 500-1000 U/mL). In two of the HIV-infected patients, phagocytes were incubated with or without interleukin (IL)-2 or IL-8 (500-1000 U/mL). Compared with that in HIV-infected patients, the reduction of M. bovis growth at 24 hours was 81% greater among monocytes and 69% greater among neutrophils from healthy controls (P =.03 and.04, respectively). Among HIV-infected patients, we noted greater mycobacterial reduction in monocytes (49%, P =.04) and neutrophils (42%, P =.05) from the early-stage patients (mean CD4 count = 760/mm(3)) compared with that in late-stage patients (mean CD4 count = 172/ mm(3)). Incubation with GM-CSF, IL-2, or IL-8 did not augment mycobactericidal activity. These findings suggest that the capacity of neutrophils and monocytes from HIV-infected patients to inhibit the growth of M. bovis is impaired, and this impairment is more pronounced in later stages of HIV infection.

MAP kinase upregulation after hematopoietic differentiation: role of chemotaxis

Mitogen-activated protein kinase (MAPK) isoform p42 is known to be active in exponentially growing cells at several points of the cell cycle. A high basal activity was present in three cell lines representative of immature myeloid cells tested: uHL-60, AML-14, and MPD. However, DMSO-induced differentiation of HL-60 cells (dHL-60) and subsequent expression of the neutrophilic phenotype occurred with a concomitant reduction on the basal level of MAPK activity. Simultaneously, extracellular stimuli like the cytokine granulocyte/macrophage colony-stimulating factor (GM-CSF) induced a fast (<10 min) and robust response. In terms of MAPK activity, the more mature the cell was, the higher the corresponding activity, in the three differentiation series considered: AML-14 < 3D10; MPD < G-MPD; uHL-60 < dHL-60 < neutrophils. Interestingly, peripheral blood neutrophils expressed the highest (16-fold) MAPK activation level in response to GM-CSF. Finally, using the specific MAPK inhibitor PD-98059, we demonstrated that MAPK activation is needed for neutrophil chemotaxis toward interleukin-8 and its priming by GM-CSF. Since neutrophils are terminally differentiated cells, GM-CSF does not serve a purpose in proliferation, and it must trigger the recruitment of selective signal transduction pathways particular to that final stage that includes enhanced physiological functions such as chemotaxis.

Haematological aspects of HIV infection

Multiple interacting factors contribute to the haematological manifestations of HIV disease. The effects of HIV-1 infection influence all haemopoietic cell lineages resulting in a spectrum of haematological abnormalities. Even in the absence of other pathological processes, bone marrow morphology is invariably abnormal, and anaemia, neutropenia and thrombocytopenia are all common during the course of disease. Intercurrent opportunistic infections may cause bone marrow suppression or induce specific cytopenias. Therapies used to treat HIV and its complications are frequently implicated as the cause of haematological dysfunction, and many have significant myelotoxic side-effects. Insights into the molecular basis for many of these abnormalities have permitted a clearer understanding of the pathophysiology of HIV-1 infection. Recombinant human growth factors that may be used to treat isolated cytopenias or to ameliorate the myelotoxic effects of other essential therapies. Lymph opoietic growth factors and the use of gene modified cells provide future therapeutic strategies that may alter the course of HIV disease.

Biopharmaceutical drug development: Filgrastim (r-metHuG-CSF) use in patients with HIV infection

Hematopoietic growth factors are well known to increase neutrophil counts and support the administration of myelotoxic and myelosuppressive therapies, especially chemotherapies. Filgrastim (r-metHuG-CSF) has been used in the setting of HIV disease to treat neutropenia and HIV-associated neutrophil defects. This article reviews the biology, product characteristics, and preclinical and clinical development of Filgrastim. Emphasis is given on the use of Filgrastim in the setting of HIV infection and AIDS.

Effects of recombinant bovine granulocyte-macrophage colony-stimulating factor on bovine peripheral blood neutrophil functions in vitro and in vivo

Effects of recombinant bovine granulocyte-macrophage colony-stimulating factor (rboGM-CSF) on bactericidal activity of bovine peripheral blood neutrophils in vitro and in vivo were studied. In in vitro experiment, bovine blood neutrophils were cultured for 9 hr in media containing 0.005, 0.05 or 0.5 microg/ml of rboGM-CSF. Neutrophils treated with rboGM-CSF showed significantly higher luminol-dependent chemiluminescence (LDCL) than control cells. In in vivo experiment, neutrophils isolated from cows injected 5.0 microg/kg of rboGM-CSF showed significantly higher Nitrobluetetrazolium (NBT) reduction value than that from control cows 24 hr post injection. Total leukocyte counts of cows injected rboGM-CSF sharply decreased 6 hr post injection and recovered to normal level 2 days post injection. Body temperature of these cows rose 6 hr post injection and back to normal level at 24 hr post injection. It was suggested that rboGM-CSF enhanced bactericidal activity of bovine neutrophils both in vitro and in vivo.

Ex vivo expansion and differentiation of unselected peripheral blood progenitor cells in serum-free media

The ability to expand and differentiate unselected PBPC was investigated. Cells were grown in serum-free media containing stem cell factor, GCSF and megakaryocyte growth and development factor (pegylated PEG-rHuMGDF) with or without supplemental serum. Optimal proliferation occurred when PBPC were cultured without prior Ficoll-Paque separation in serum-free media. Cell yields after 17 days of culture were proportional to the percentage of CD34+ cells in the starting population and were 1170+/-302-fold higher than the starting numbers of CD34+ cells. Granulocyte-macrophage colony-forming units increased over 12 days of culture, whereas the numbers of erythroid colony-forming cells peaked between 4 and 7 days. Elimination of PEG-rHuMGDF from cell cultures resulted in significantly lower yields of myeloid and erythroid colony-forming cells and total cell numbers. Cell differentiation into neutrophils was indicated by progressive increases in CD11b, CD15, and CD66b expression. Expanded neutrophils phagocytosed and killed bacteria as efficiently as neutrophils from normal donors. Large-scale expansion studies yielded similar proliferation and differentiation results as parallel small-scale cultures. Therefore, unselected PBPC can be efficiently expanded and differentiated into large numbers of functional mature neutrophils.

Marijuana and cocaine impair alveolar macrophage function and cytokine production

Use of marijuana and cocaine is on the rise in the United States. Although pulmonary toxicity from these drugs has occasionally been reported, little is known about their effects on the lung microenvironment. We evaluated the function of alveolar macrophages (AMs) recovered from the lungs of nonsmokers and habitual smokers of either tobacco, marijuana, or crack cocaine. AMs recovered from marijuana smokers were deficient in their ability to phagocytose Staphylococcus aureus (p < 0.01). AMs from marijuana smokers and from cocaine users were also severely limited in their ability to kill both bacteria and tumor cells (p < 0.01). Studies using NG-monomethyl-L-arginine monoacetate, an inhibitor of nitric oxide synthase, suggest that AMs from nonsmokers and tobacco smokers were able to use nitric oxide as an antibacterial effector molecule, while AMs from smokers of marijuana and cocaine were not. Finally, AMs from marijuana smokers, but not from smokers of tobacco or cocaine, produced less than normal amounts of tumor necrosis factor-alpha, granulocyte-macrophage colony-stimulating factor, and interleukin-6 when stimulated in culture with lipopolysaccharide. In contrast, the production of transforming growth factor-beta, an immunosuppressive cytokine, was similar in all groups. These findings indicate that habitual exposure of the lung to either marijuana or cocaine impairs the function and/or cytokine production of AMs. The ultimate outcome of these effects may be an enhanced susceptibility to infectious disease, cancer, and AIDS.

Conformation of four peptides corresponding to the alpha-helical segments of human GM-CSF

The conformation of segments corresponding to the four alpha-helical stretches found in human granulocyte-macrophage colony-stimulating factor was studied in water solution in the presence of different amounts of 2,2,2-trifluoroethanol (TFE). The CD spectra reveal the onset of secondary structure upon addition of TFE. The final amount of helical conformation varies among the four peptides. In all cases, the conformational transition is complete before 50% TFE (v/v). 1H-NMR studies were conducted at this solvent composition, leading to the assignment of all the resonances and to the definition of the secondary structure for all four fragments.

Gene therapy for metastatic brain tumors by vaccination with granulocyte-macrophage colony-stimulating factor-transduced tumor cells

We have developed an ex vivo gene therapy paradigm for the treatment of brain tumors using granulocyte-macrophage colony-stimulating factor (GM-CSF). Murine B16 melanoma cells were infected with MFG recombinant retrovirus containing the mouse GM-CSF cDNA. Subcutaneous vaccination of syngeneic mice with irradiated GM-CSF-secreting B16 melanoma cells was capable of completely protecting animals against subsequent intracranial B16 tumor inoculation, with up to 5 x 10(3) cells. Histologic evaluation revealed the presence of neutrophils, eosinophils, and lymphocytes, including CD4+, CD8+, and CD45R+ cells, in the intracerebral inoculation site, peaking 4 days after intracranial inoculation. In contrast, nonvaccinated animals or animals vaccinated with irradiated, nontransduced B16 cells succumbed to intracranial tumor within 3 weeks after inoculation. Treatment of established intracranial B16 melanoma tumors with subcutaneous injection of irradiated GM-CSF-secreting B16 cells significantly delayed death, as compared to injection of irradiated nontransduced B16 cells or no treatment. In addition, treatment of established intracerebral GL261 gliomas by vaccination with irradiated GM-CSF-secreting B16 cells mixed with irradiated, transduced, or nontransduced GL261 cells also extended survival. These B16/GL261 co-vaccinations also improved outcome and, in some cases, induced immunological memory that protected survivors from subsequent intracranial challenge with GL261 tumor cells. These findings indicate that peripheral vaccination with irradiated tumor cells in the presence of GM-CSF-producing cells can initiate a potent antitumor immune response against intracranial neoplasms.

Haemopoietic growth factors

Haemopoietic growth factors are involved in the production of the various blood cells from progenitors in the bone marrow, making them useful in a range of clinical situations. The genes for several of them have been cloned and their production engineered by recombinant technology, making them widely available. Myeloid growth factors are used to support patients in the aftermath of chemotherapy and bone marrow transplantation and have potential application in the treatment of infectious diseases. Erythropoietin is widely used for patients with anaemia due to failure of marrow production, having established its effectiveness in chronic renal failure. Thrombopoietin has recently been described and may provide a means to alleviate thrombocytopenia. Current indications and areas of recent reappraisal are addressed in this review.

Acute activation of circulating polymorphonuclear neutrophils following in vivo administration of cocaine. A potential etiology for pulmonary injury

Crack cocaine has become a major drug of abuse in the United States and its use is associated with a broad spectrum of pulmonary complications. The present study was conducted to determine whether controlled in vivo administration of cocaine (inhaled or IV) alters the function of circulating inflammatory cells in a manner capable of contributing to acute lung injury. Subjects who regularly smoked crack cocaine were asked to abstain from illicit drug use for at least 8 h, and were then administered one of the following treatments on each of 4 study days: inhaled cocaine base (45 mg), inhaled placebo (4.5 mg cocaine base, a subphysiologic dose), IV cocaine HCl (0.35 to 0.50 mg/kg), or IV placebo (saline solution). Samples of blood were obtained from a peripheral venous catheter and blood cells were isolated before and 10 to 45 min after treatment. The administration of either cocaine base or cocaine HCl, but not their corresponding placebos, resulted in the activation of circulating polymorphonuclear neutrophils (PMNs). Exposure to cocaine in vivo enhanced the antibacterial activity of PMNs, as measured by their ability to kill Staphylococcus aureus. Antitumor activity, as measured in an antibody-dependent cell-mediated cytotoxicity assay, also increased following short-term administration of cocaine. Finally, short-term exposure to cocaine enhanced production of interleukin 8, a potent PMN chemoattractant and neutrophil-activating factor associated with both acute and chronic lung injury. These studies demonstrate that short-term in vivo exposure to cocaine activates the effector function and cytokine production of circulating PMNs. Therefore, it is possible that bursts of acute inflammatory activity resulting from crack use could contribute to lung injury.

Priming of neutrophil and monocyte activation in human immunodeficiency virus infection. Comparison of granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor and interferon-gamma

Activation of human blood neutrophils and monocytes for enhanced release of toxic oxygen radicals may take place after priming with several cytokines including hematopoietic growth factors. The potential impact of human immunodeficiency virus (HIV) on this response and the relative potency of various cytokines remains unclear. Blood neutrophils and monocytes were isolated from 25 HIV outpatients with variable immunodeficiency. Oxidative burst response upon stimulation with N-formyl-methionyl-leucyl-phenylalanine was assessed in neutrophils after priming with granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF) and interferon-gamma (IFN-g), and in monocytes after priming with GM-CSF and IFN-g. Monocyte oxidative burst responses were not changed in patients or controls. In contrast, following priming with IFN-g, GM-CSF or medium (but not G-CSF) the neutrophils in HIV patients with CD4 counts > 200 x 10(9)/L exhibited a significantly higher chemiluminescence response than was seen in healthy age-matched controls, whereas the response in patients with lower CD4 counts was not different from controls. At comparable concentrations, GM-CSF induced a significantly higher priming than G-CSF and IFN-g. A significant positive correlation between CD4 counts and priming activity of GM-CSF and IFN-g on neutrophils was observed. We conclude that neutrophils in HIV infection have a normal or enhanced response to the oxidative metabolism priming activity of hematopoietic growth factors in vitro, whereas priming effect on monocytes was not seen.

Nontropical pyomyositis in patients with AIDS

Nontropical pyomyositis in persons with acquired immunodeficiency syndrome (AIDS) is an unusual entity with only a few cases having been described in the United States. Staphylococcus aureus is the most common organism implicated. The infection usually presents in a subacute indolent fashion with minimal inflammation. Fever and leukocytosis may be absent, and blood cultures are frequently negative. The diagnosis usually can be established by a combination of clinical features, computed tomography or ultrasound, and prompt examination of material obtained by aspiration or debridement. This article describes two cases of S aureus pyomyositis in patients with AIDS and reviews the literature relevant to this infection.

Lack of in vivo effect of granulocyte-macrophage colony-stimulating factor on human immunodeficiency virus type 1

Neutropenia complicates HIV disease or its treatment in a large proportion of patients. Hematopoietic growth factor support has been tested in a number of clinical settings in HIV disease and has been demonstrated to be of benefit for specific parameters. One consideration regarding the use of hematopoietic growth factors in HIV disease is their potential effect on HIV viral burden, since alterations in HIV expression have been documented with certain cytokines in vitro. It has also been reported that some cytokines, notably GM-CSF, potentiate the antiviral properties of thymidine analogs such as zidovudine (AZT) in vitro. We tested these observations in vivo. Twelve HIV-positive patients with a CD4 cell count < or = 200/mm3 or HIV plasma viremia who were receiving a stable dose of zidovudine were enrolled into three dose cohorts of yeast-derived GM-CSF at 50, 125, or 250 micrograms/m2 daily by subcutaneous self-injection for 28 days. Measurements of HIV activity included serum acid-dissociated HIV p24 antigen levels, plasma and peripheral blood mononuclear cell (PBMC) limiting dilution HIV culture, and plasma HIV quantitative competitive polymerase chain reaction (PCR). Serum and intracellular zidovudine levels were measured as well as hematologic, immunologic, and toxicity parameters. Virologic measures showed neither significant upregulation nor downregulation of serum acid-dissociated HIV p24 antigen, plasma and PBMC HIV culture, or PCR in association with GM-CSF administration. A trend toward increased intracellular AZT levels was noted, but this did not achieve statistical significance (p = 0.073). CD4 and CD8 lymphocytes were essentially unaffected while absolute neutrophil counts increased with GM-CSF administration as expected. These data suggest that administration of GM-CSF does not perturb HIV activity or immunologic parameters in patients receiving AZT for advanced HIV disease. No potentiation of AZT antiviral effect was demonstrated.

Recombinant human granulocyte-macrophage colony-stimulating factor (rHuGM-CSF) in leukopenic patients with advanced HIV disease

In order to assess the efficacy and safety of recombinant human granulocyte-macrophage colony-stimulating factor (rHuGM-CSF) in the treatment of HIV-associated leukopenia, 35 subjects suffering from severe leukopenia/neutropenia (24 with a previous diagnosis of AIDS, 11 with AIDS-related complex), received rHuGM-CSF at 0.5-3 micrograms/Kg/day subcutaneously for a mean period of 9.7 +/- 12.5 weeks (range 2-43 weeks). Five patients have been treated continuously for more than 6 months. rHuGM-CSF administration led to a significant (at least two-fold; P < .001) increase in total leukocyte, neutrophil and monocyte count by the second week of treatment, subsequently maintained through the entire course of therapy. No considerable effects on other hematological, immunological and virological parameters have been detected. Patients treated with rHuGM-CSF did not suffer from novel opportunistic diseases, while bacterial infections occurred in only 3 cases (pneumonia in 2, otitis/mastoiditis in 1). Long-term treatment with rHuGM-CSF allowed continuation or resumption of potentially myelotoxic drugs in 22 patients out of 35. A self-limited flu-like syndrome represented the most common adverse event (observed in 15 patients), while no other significant clinical or laboratory abnormalities were found. In conclusion, long-term rHuGM-CSF therapy showed a good efficacy and safety profile in the treatment of HIV-related leukopenia, also increasing tolerability to potentially myelosuppressive drugs, and leading to a significant reduction in morbidity due to secondary infections.

Gene therapy for brain tumors

Gene therapy has opened new doors for treatment of neoplastic diseases. This new approach seems very attractive, especially for glioblastomas, since treatment of these brain tumors has failed using conventional therapy regimens. Many different modes of gene therapy for brain tumors have been tested in culture and in vivo. Many of these approaches are based on previously established anti-neoplastic principles, like prodrug activating enzymes, inhibition of tumor neovascularization, and enhancement of the normally weak anti-tumor immune response. Delivery of genes to tumor cells has been mediated by a number of viral and synthetic vectors. The most widely used paradigm is based on the activation of ganciclovir to a cytotoxic compound by a viral enzyme, thymidine kinase, which is expressed by tumor cells, after the gene has been introduced by a retroviral vector. This paradigm has proven to be a potent therapy with minimal side effects in several rodent brain tumor models, and has proceeded to phase 1 clinical trials. In this review, current gene therapy strategies and vector systems for treatment of brain tumors will be described and discussed in light of further developments needed to make this new treatment modality clinically efficacious.

In vivo administration of granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor increases neutrophil oxidative burst activity

The influence of CSF therapy on the superoxide (O2-) releasing capacity in response to N-formyl-methionyl-leucyl-phenylalanine (FMLP) of neutrophils from 32 patients with testicular cancer receiving high-dose chemotherapy followed by autologous bone marrow transplantation (ABMT) was assessed: 8 patients were treated as control group without CSF therapy, 12 patients received GM-CSF, and 12 patients received G-CSF. To monitor the kinetics of the respiratory burst, leukocytes were collected before initiation of chemotherapy and ABMT, during CSF administration on days 1 and 3 after leukocyte recovery, and 7 days after leukocyte recovery (controls) or 3 days after the end of CSF therapy. Neutrophils from patients who received GM-CSF showed a significantly higher superoxide anion release compared with control patients (p < 0.001). O2- production in these patients was higher than that achieved by in vitro preincubation of neutrophils from control patients. Increased burst activity was seen only during infusion of GM-CSF and returned to pretherapeutic values after the end of GM-CSF administration. A similar but less pronounced increase was seen in patients who received G-CSF. In vitro preincubation of neutrophils from the same patients with GM-CSF, G-CSF, or TNF showed that O2- production by neutrophils from patients receiving GM-CSF could not be further enhanced, whereas O2- production by neutrophils derived from patients receiving G-CSF could be further augmented by TNF but not by GM-CSF. Interestingly, neutrophils from patients treated with GM-CSF but not those with G-CSF therapy retained a higher response to in vitro stimulation with GM-CSF or TNF after the end of CSF administration.(ABSTRACT TRUNCATED AT 250 WORDS)

An immunodominant epitope in a functional domain near the N-terminus of human granulocyte-macrophage colony-stimulating factor identified by cross-reaction of synthetic peptides with neutralizing anti-protein and anti-peptide antibodies

We produced polyclonal and monoclonal antibodies (MAbs) against recombinant human (rh) granulocyte-macrophage colony-stimulating factor (GM-CSF) and performed studies of epitope mapping by ELISA, using five synthetic peptides corresponding to sequences along this molecule. Additionally, anti-peptide MAbs were generated. The antibody ability to inhibit rhGM-CSF activity was determined using as bioassay the MO7e cell line, which is dependent on hGM-CSF for growth in vitro. An immunodominant epitope able to induce the highest neutralization antibody titers was identified near the N terminus of hGM-CSF. A synthetic peptide 14-24, homologous to a sequence including part of the first alpha-helix of the molecule, was recognized by neutralizing anti-protein antibodies. Similarly, MAbs anti- 14-24 cross-reacted with rhGM-CSF and specifically blocked its function. Replacement of Val16 or Asn17 with alanine greatly reduced the antibody-binding capacity to peptide 14-24, whereas substitution of Gln20 or Glu21 was less critical. Monoclonal antibodies generated against residues 30-41 (corresponding to an intrahelical loop) and 79-91 (homologous to a sequence including part of the third alpha-helix) or its analog [Ala88](79-91)beta Ala-Cys, were conformation dependent and nonneutralizing: they failed to react or bound poorly to rhGM-CSF in ELISA, but readily recognized the homologous sequence in the denatured protein, by Western blotting.

Production of functional myeloid cells from CD34-selected hematopoietic progenitor cells using a clinically relevant ex vivo expansion system

There is increasing clinical interest focused on ex vivo manipulation and expansion of hematopoietic cells. In this study, we demonstrate that a simple combination of growth factors can expand progenitors to yield functional myeloid cells. Furthermore, this system can produce mature, functionally competent cells in the absence of fetal bovine serum (FBS), which will enhance the clinical utility of this approach. Hematopoietic progenitor cells obtained from normal bone marrow and from leukapheresis products were studied. The mononuclear fraction was enriched for CD34 cells using the Ceprate CD34 biotin kit (CellPro #LC34-1 or LC34-2). The selected cells were expanded for two weeks in Iscove's medium supplemented with 20% FBS and various combinations of interleukin-3 (IL-3), granulocyte colony-stimulating factor (G-CSF), stem cell factor (SCF) and interleukin -6 (IL-6) added either simultaneously or sequentially. The optimal combination of these factors identified for myeloid expansion was simultaneous addition of IL-3, SCF and G-CSF (at 50 ng/ml each), resulting in an average 773 +/- 133-fold expansion of nucleated cells (n = 5). When corrected for the purity of CD34 cells in the starting population, the mean fold expansion with IL-3, SCF and G-CSF was 2,265 +/- 729. A mean of 74.7 +/- 10.5% (n = 3) of the expanded cells was positive for CD11b; 86-91% (n = 2) of the cells were promyelocytes or more mature granulocytes. Functional assays demonstrated normal phagocytosis and intracellular killing of Staphylococcus aureus (S. aureus) by the expanded cell population. Studies performed using cells expanded in defined serum-free media demonstrated that fold expansion was decreased and that the cells produced were less mature and functionally less competent than cells expanded with FBS. The decreased expansion could be partially reversed, and the functionality almost completely restored by the addition of autologous plasma.

Cytokines in the treatment of fungal infections

The incidence of invasive fungal infections in the immunocompromized host has increased during the past decade. Even the recently developed antifungal drugs are unable to cure these infections in patients with severely impaired host defense mechanisms. Cytokines have great potential to augment host resistance and as adjunctive therapy of invasive mycoses. We discuss the mechanisms of host defense against invasive candidiasis, aspergillosis, and cryptococcosis, and review the use of cytokines and growth factors in this setting. Interleukin-1 has been shown effective in an animal model of disseminated candidiasis, even during severe granulocytopenia. Interferon-gamma has been very effective as a modulator of resistance against a variety of fungal infections in vitro. The effect of interferon-gamma against disseminated candidiasis has been demonstrated in a mouse model. Activation of neutrophils is the main mechanism by which interferon-gamma enhances the elimination of Candida, and consequently the agent is not effective in severely granulocytopenic animals. Data on the role of colony-stimulating factors against fungal pathogens are accumulating, and trials with these agents for hematologic patients with invasive fungal infections are now being performed.

Specific human granulocyte-macrophage colony-stimulating factor antagonists

Human granulocyte-macrophage colony-stimulating factor (GM-CSF) is a pleiotropic hemopoietic growth factor and activator of mature myeloid cell function. We have previously shown that residue 21 in the first helix of GM-CSF plays a critical role in both biological activity and high-affinity receptor binding. We have now generated analogues of GM-CSF mutated at residue 21, expressed them in Escherichia coli, and examined them for binding, agonistic, and antagonistic activities. Binding experiments showed that GM E21A, E21Q, E21F, E21H, E21R, and E21K bound to the GM-CSF receptor alpha chain with a similar affinity to wild-type GM-CSF and had lost high-affinity binding to the GM-CSF receptor alpha-chain-common beta-chain complex. From these mutants, only the charge reversal mutants E21R and E21K were completely devoid of agonistic activity. Significantly we found that E21R and E21K antagonized the proliferative effect of GM-CSF on the erythroleukemic cell line TF-1 and primary acute myeloid leukemias, as well as GM-CSF-mediated stimulation of neutrophil superoxide production. This antagonism was specific for GM-CSF in that no antagonism of interleukin 3-mediated TF-1 cell proliferation or tumor necrosis factor alpha-mediated stimulation of neutrophil superoxide production was observed. E. coli-derived GM E21R and E21K were effective antagonists of both nonglycosylated and glycosylated wild-type GM-CSF. These results show that low-affinity GM-CSF binding can be dissociated from receptor activation and have potential clinical significance for the management of inflammatory diseases and certain leukemias where GM-CSF plays a pathogenic role.

Inhibition of leukemic cell proliferation by factor(s) released from irradiated lymphocytes of B-chronic lymphocytic leukemia patients

An attempt was made to clarify the mechanism by which splenic irradiation in patients with B-chronic lymphocytic leukemia (B-CLL) can induce a reduction in lymph node size. For this purpose peripheral blood lymphocytes from B-CLL patients were exposed to cobalt irradiation and were cultured for 1-8 days. The effect of the supernatants on the proliferation capacity of normal and malignant human cells was examined. A suppression of phytohemagglutinin (PHA)-induced proliferation of autologous and heterologous B-CLL lymphocytes was observed, whereas there was no effect on the proliferation of lymphocytes obtained from healthy volunteers. In addition, supernatants of irradiated B-CLL lymphocytes inhibited thymidine incorporation into blasts derived from patients with acute leukemia and the lymphoblastoid cell line Daudi, but they did not exert any effect on normal cells obtained from human embryonic liver. These results suggest the secretion of some factor(s) by irradiated B-CLL lymphocytes, which may inhibit the proliferation of malignant cells but has no effect on normal cells.

Comparison of cytotoxic properties of neonatal and adult neutrophils and monocytes and enhancement by cytokines

We studied cytotoxic capabilities of newborn polymorphonuclear leukocytes (PMNs) and monocytes and their enhancement by cytokines and antibodies. Umbilical cord PMNs were assessed for their ability to kill various target cells spontaneously, after activation with phorbol myristate acetate, in the presence of antiserum (antibody-dependent cellular cytotoxicity), and in the presence of dually specific antibody (heteroantibody-mediated cytotoxicity). Target cells included the K562 cell line (natural killer cell target), chicken erythrocytes (CRBCs), and herpes simplex virus-infected CEM cell lines. Newborn PMNs were equivalent to adult PMNs in their cytotoxic capacity in several cytotoxicity assays. Neither adult nor newborn PMNs lyse tumor cell targets (i.e., K562 cells) spontaneously, but both lyse K562 cells following activation with phorbol myristate acetate. Both adult and newborn PMNs lyse CRBCs and herpes simplex virus-infected CEM cells in antibody-dependent cellular cytotoxicity assays, and this lysis could be enhanced by the cytokines granulocyte-macrophage colony-stimulating factor and gamma interferon. PMN heteroantibody-mediated cytotoxicity, resulting from the use of an antibody with dual specificity to CRBCs and immunoglobulin G FcRII, was greater in newborn PMNs than in adult PMNs; however, monocyte heteroantibody-mediated cytotoxicity, resulting from the use of an antibody to CRBCs and monocyte immunoglobulin G FcRI, was lower in newborn monocytes than in adult monocytes. The percentage, but not the density, of PMNs expressing FcRII was significantly reduced in newborn PMNs compared with that in adult PMNs, while the percentages and densities of FcRI expression were equivalent in newborn and adult monocytes. We conclude that the cytotoxic capability in term newborn PMNs is equivalent to that in adult PMNs, that the activity of newborn PMNs can be enhanced by antibody and/or cytokines, and that PMNs can contribute to the newborn's ability to kill virus-infected cells.

The effects of human immunodeficiency virus infection on macrophage phagocytosis of Candida

The effects of infection by human immunodeficiency virus (HIV) on phagocytic function towards Candida pseudotropicalis were tested using monocytotropic and nonmonocytotropic HIV strains on peripheral blood monocytes. There were no differences in either quantitative phagocytic activity or efficacy between the two infected and control mock-infected monocytes. Immunofluorescence for cytoplasmic p24 antigen and in situ hybridization for detection of HIV-specific RNA sequences revealed that very few cells (10(-4)) exhibit productive infection. Occasional cells with active infection as defined by microscopically detectable fluorescence labelling contained phagocytized yeasts.

Clinical significance of neutrophil functional activity in HIV infection

Functional activity of polymorphonuclear neutrophils (PMN) was tested in 63 HIV-1 infected patients. PMN chemiluminescence (CL) and intracellular enzyme activity were both depressed in patients at all stages of infection, though this depression was more pronounced in AIDS patients. We found no such depression when cells were incubated in the presence of autologous serum. PMN phagocytosis in the presence of serum was reduced in the early stage of HIV infection (LAS) but was in the normal range in AIDS patients. No differences in PMN functional activity between patients with LAS and those with dermatological disorders were found. The appearance of recurrent upper respiratory tract infection was associated with reduced PMN CL. The most pronounced changes in PMN activity were observed in patients with severe, recurrent bacterial pneumonia and Pneumocystis carinii pneumonia. A lower level of PMN activity was found in patients with infection progressing rapidly towards AIDS than in patients with a relatively stable course of infection. Thus, PMN CL may be regarded as a predictive factor for the progression of HIV infection.

Integrating worldwide marketing needs and clinical research

In this era of globalization, expanding research needs, and the necessity of sharing global technologies and worldwide data evaluation techniques, a challenging environment has been created for multinational drug development, clinical testing, and marketing. Integrating worldwide marketing needs and clinical research will become even more significant in the future as harmonization of pharmaceutical industry research and regulatory requirements increase with the unification of the European Economic Community. Marketing and research teams within a pharmaceutical company must work closely together to make the drug being developed appropriate to a global market.