Granulocyte-macrophage colony-stimulating factor is a stimulant of platelet-activating factor and superoxide anion generation by human neutrophils

Mechanisms, Cofactors, and Augmenting Factors Involved in Anaphylaxis

Anaphylaxis is an acute and life-threatening systemic reaction. Many triggers have been described, including food, drug, and hymenoptera allergens, which are the most frequently involved. The mechanisms described in anaphylactic reactions are complex and implicate a diversity of pathways. Some of these mechanisms may be key to the development of the anaphylactic reaction, while others may only modify its severity. Although specific IgE, mast cells, and basophils are considered the principal players in anaphylaxis, alternative mechanisms have been proposed in non-IgE anaphylactic reactions. Neutrophils, macrophages, as well as basophils, have been involved, as have IgG-dependent, complement and contact system activation. A range of cationic substances can induce antibody-independent mast cells activation through MRGPRX2 receptor. Cofactors and augmenting factors may explain why, in some patients, food allergen exposure can cause anaphylaxis, while in other clinical scenario it can be tolerated or elicits a mild reaction. With the influence of these factors, food allergic reactions may be induced at lower doses of allergen and/or become more severe. Exercise, alcohol, estrogens, and some drugs such as Non-steroidal anti-inflammatory drugs, angiotensin-converting enzyme inhibitors, β-blockers, and lipid-lowering drugs are the main factors described, though their mechanisms and signaling pathways are poorly understood.

Functional Starters for Functional Yogurt

In this study, we investigated the multifunctionality (microbial starters and probiotics) of Lactobacillus plantarum WCFS1 and Lactobacillus plantarum CECT 8328 strains used as microbial starters for the production of yogurt in combination with Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus. The ability of the probiotic strains to survive oro-gastrointestinal stresses was monitored by an in vitro assay simulating the human digestive tract. The transcriptional level of several genes involved in the immune response suggested that the probiotic strains may have a favorable influence on immunomodulation. Overall, this study revealed that the tested Lactobacilli exhibited suitable technological features for yogurt production and might be used to formulate novel food with immunomodulating effects.

Growth factor pleiotropy is controlled by a receptor Tyr/Ser motif that acts as a binary switch

Pleiotropism is a hallmark of cytokines and growth factors; yet, the underlying mechanisms are not clearly understood. We have identified a motif in the granulocyte macrophage-colony-stimulating factor receptor composed of a tyrosine and a serine residue that functions as a binary switch for the independent regulation of multiple biological activities. Signalling occurs either through Ser585 at lower cytokine concentrations, leading to cell survival only, or through Tyr577 at higher cytokine concentrations, leading to cell survival as well as proliferation, differentiation or functional activation. The phosphorylation of Ser585 and Tyr577 is mutually exclusive and occurs via a unidirectional mechanism that involves protein kinase A and tyrosine kinases, respectively, and is deregulated in at least some leukemias. We have identified similar Tyr/Ser motifs in other cell surface receptors, suggesting that such signalling switches may play important roles in generating specificity and pleiotropy in other biological systems.

Carboxy-terminal truncated STAT5 is induced by interleukin-2 and GM-CSF in human neutrophils

IL-2 and GM-CSF are potent activators of polymorphonuclear neutrophils (PMN) biologic activity. IL-2 and GM-CSF-mediated activation of STAT proteins was examined in nuclear extracts of human PMN. We found that both cytokines induced STAT5-like DNA-binding complexes that could not be supershifted using C-terminal-specific anti-STAT5 antibodies. Therefore, we performed oligoprecipitation experiments with a STAT5-biotinylated DNA probe (biotin-MGFe) and the precipitated proteins were identified by Western immunoblotting. We found that GM-CSF and IL-2 induced the DNA-binding activity of a C-terminal truncated isoform of STAT5. The truncated STAT5 form was present in the nucleus of PMN but the cytoplasmic extracts contained full-length STAT5, suggesting that PMN proteolytically process full-length STAT5 proteins. Proteolytic experiments demonstrated that PMN express a protease activity capable of producing C-terminal processed STAT5 proteins. In many settings, C-terminal truncation of the STAT5 protein leads to inhibition of STAT5 biological activity. Two known STAT5 regulated genes, encoding pim-1 and OSM proteins, failed to be induced by GM-CSF in PMN. These findings provide new insights to a mechanism by which PMN, a terminally differentiated cell, may regulate gene transcription by alternative proteolytic processing.

Diverse effects of cytochalasin B on priming and triggering the respiratory burst activity in human neutrophils and monocytes

Cytochalasin B, despite its potent enhancing effect on superoxide (O2-) release triggered by N-formyl-methionyl-leucyl-phenylalanine (FMLP) and many other agonists, significantly inhibited O2- release triggered by interleukin 8 (IL-8) and platelet-activating factor in human neutrophils. Cytochalasin B also enhanced changes in membrane potential stimulated by FMLP but inhibited those stimulated by IL-8. Using IL-8 as a triggering agonist, we found that the priming effect of tumor necrosis factor (TNF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) on O2- release was slightly but significantly potentiated by cytochalasin B. O2- release triggered by TNF and GM-CSF was completely abolished by cytochalasin B. In contrast to these diverse effects of cytochalasin B on O2- release, changes in cytoplasmic pH stimulated by FMLP, IL-8, TNF, and GM-CSF were not or were only minimally affected by cytochalasin B. Unlike human neutrophils, human monocytes stimulated by FMLP showed inhibition of O2- release and changes in membrane potential in response to cytochalasin B, and the priming effect of TNF and GM-CSF on O2- release in human monocytes was completely abolished by cytochalasin B. These findings indicate the diverse effects of cytochalasin B on phagocytes and suggest distinct regulatory mechanisms according to the functions, agonists, and cell types.

Activation of human neutrophil by cytokine-activated endothelial cells

Cytokine activation of vascular endothelial cells renders the hyperadhesiveness for neutrophils. During the processes of inflammation and atherosclerosis, the production of reactive oxygen species by neutrophils contributes to endothelial cell (EC) damage and injury. However, the precise mechanisms for neutrophil activation by ECs remain unknown. Thus, we investigated what kinds of pathophysiological factors synthesized by inflammatory cytokine-activated ECs potentiated the activity of neutrophil functions. The magnitude of O(2)(-) release from neutrophils, which is one of pivotal neutrophil functions, was measured as an indicator potentiated by activated ECs. Neutrophils release massive amounts of O(2)(-) on coculture with activated ECs. Anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) antibody (Ab) or specific platelet-activating factor (PAF)-receptor antagonist suppressed the O(2)(-) release from neutrophils on coculture with the activated ECs by 50% to 70%. The supernatants from activated ECs also induced O(2)(-) release by neutrophils. This stimulatory effect of activated EC supernatants on O(2)(-) release by neutrophils was abolished by anti-GM-CSF Ab or by PAF-receptor antagonist. As we previously reported, we demonstrated the expression of GM-CSF mRNA by Northern blotting and protein synthesis of GM-CSF by ELISA on tumor necrosis factor as well as interleukin-1-activated ECs. Although phosphorylation of mitogen-activated protein kinases was observed in ECs stimulated by tumor necrosis factor and interleukin-1, treatment of ECs with PD98059 (MEK1 inhibitor) and SB203580 (p38 mitogen-activated protein kinase inhibitor) in the presence of the cytokine failed to attenuate the stimulatory effect of activated ECs on neutrophil activation. We found that activated ECs regulated neutrophil function on coculture. We show here for the first time, to our knowledge, that the collaboration between GM-CSF and PAF synthesized by activated ECs markedly potentiated neutrophil activation.

Caspases Mediate Tumor Necrosis Factor-–Induced Neutrophil Apoptosis and Downregulation of Reactive Oxygen Production

Tumor necrosis factor- (TNF-) exerts two separate effects on neutrophils, stimulating effector functions while simultaneously inducing apoptosis. We examined here the involvement of caspases in neutrophil apoptosis and the effect of TNF-–induced apoptosis on reactive oxygen production. Immunoblotting and affinity labeling showed activation of caspase-8, caspase-3, and a caspase with a large subunit of 18 kD (T18) in TNF-–treated neutrophils. Active caspase-6 and -7 were not detectable in this cell type. Caspase-8 activated caspase-3 and T18 in neutrophil cytoplasmic extracts. zVAD-fmk blocked neutrophil apoptosis, in parallel with the inhibition of caspase activation. TNF-–induced caspase activation was accompanied by a decrease in the ability of neutrophils to release superoxide anion. Conversely, TNF- treatment in the presence of zVAD-fmk caused a prolonged augmentation of superoxide release. Granulocyte-macrophage colony-stimulating factor inhibited TNF-–induced caspase activation and apoptosis, while reversing the diminution in superoxide release. These observations not only suggest that a caspase cascade mediates apoptotic events and downregulates oxygen radical production in TNF-–treated neutrophils, but also raise the possibility that suppression of caspase activation with enhanced proinflammatory actions of TNF- may underlie the pathogenesis of inflammatory diseases.

Caspases Mediate Tumor Necrosis Factor-–Induced Neutrophil Apoptosis and Downregulation of Reactive Oxygen Production

Tumor necrosis factor- (TNF-) exerts two separate effects on neutrophils, stimulating effector functions while simultaneously inducing apoptosis. We examined here the involvement of caspases in neutrophil apoptosis and the effect of TNF-–induced apoptosis on reactive oxygen production. Immunoblotting and affinity labeling showed activation of caspase-8, caspase-3, and a caspase with a large subunit of 18 kD (T18) in TNF-–treated neutrophils. Active caspase-6 and -7 were not detectable in this cell type. Caspase-8 activated caspase-3 and T18 in neutrophil cytoplasmic extracts. zVAD-fmk blocked neutrophil apoptosis, in parallel with the inhibition of caspase activation. TNF-–induced caspase activation was accompanied by a decrease in the ability of neutrophils to release superoxide anion. Conversely, TNF- treatment in the presence of zVAD-fmk caused a prolonged augmentation of superoxide release. Granulocyte-macrophage colony-stimulating factor inhibited TNF-–induced caspase activation and apoptosis, while reversing the diminution in superoxide release. These observations not only suggest that a caspase cascade mediates apoptotic events and downregulates oxygen radical production in TNF-–treated neutrophils, but also raise the possibility that suppression of caspase activation with enhanced proinflammatory actions of TNF- may underlie the pathogenesis of inflammatory diseases.

Comparison of neutrophil and monocyte function by microbicidal cell-kill assay in patients with cancer receiving granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, or no cytokine after cytotoxic chemotherapy: a phase II trial

Functional effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) and recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) were prospectively measured by harvesting blood samples from 51 oncology patients (21 who were receiving no cytokines, 14 receiving rhGM-CSF, and 16 who were receiving rhG-CSF) just before cytotoxic chemotherapy (baseline) immediately before the last cytokine dose (pre), 2 hours after the last cytokine dose (post), and 48 hours after the pre period (follow-up). Neutrophils and monocytes were separated and functional effects were measured by comparing cell-kill percentages, as determined by a microbial cell-kill assay against Staphylococcus aureus and Candida albicans. Optimal cell concentrations (2 x 10(6) monocytes/ml; 4 x 10(6) neutrophils/ml) and effector-to-cell ratios (1:50) were initially determined with blood samples harvested from 23 healthy volunteers. Results in oncology patients indicated that rhGM-CSF improved monocyte-killing activity against S. aureus at follow-up, compared with controls (p = 0.0094) and compared with monocytes from rhG-CSF-treated patients at the post period (p = 0.014). Cell-killing percentage of the rhGM-CSF-treated patients was also enhanced against C. albicans during the post period, compared with controls (p = 0.011) and rhG-CSF-treated patients (p = 0.067). Neutrophil activity was not altered by either cytokine. In conclusion, monocyte-induced microbial killing was enhanced in oncology patients receiving rhGM-CSF after cytotoxic chemotherapy, compared with patients receiving rhG-CSF or no cytokines. No differences in neutrophil activity were observed between patients receiving either cytokine.

Factors influencing the outcome of donor marrow transplantation in adults from less than ideal donors: experience from two Australian centres

BACKGROUND

This paper reports the results of 78 marrow transplants in two Australian hospitals between 1991 and 1996, using unrelated (n = 54) or mismatched related (n = 24) donors. Twenty-six patients received granulocyte-macrophage colony stimulating factor (GM-CSF) post-transplant as part of a phase II study. Fifty-four patients (74%) had advanced disease.

AIMS

To identify factors associated with a superior outcome post-transplant, to evaluate the effect of GM-CSF on engraftment and other transplant parameters, and to compare the overall results with those of published series.

METHODS

Review of patient records, a Medline search of the relevant literature and appropriate statistical analysis.

RESULTS

The probability of overall survival and event-free survival (EFS) at three years was 35 +/- 6% and 22 +/- 6% respectively. Pre-transplant factors significantly associated with an inferior EFS were advanced disease, poorer performance status and age > 30 years. The EFS in patients with standard risk disease was 51 +/- 13% versus 10 +/- 5% in patients with advanced disease, p < 0.0001. Severe acute graft-versus-host disease was also associated with a poorer outcome. Neutrophil engraftment was faster in patients who received GM-CSF but there was no difference in any other transplant parameters.

CONCLUSIONS

These results are consistent with reported series elsewhere and suggest that an extended family or unrelated donor transplant should generally be limited to patients with a good performance status and early phase but otherwise incurable haematological disease.

Production and metabolism of platelet-activating factor by human bone marrow cells

Platelet-activating factor (PAF) is a phospholipid mediator of inflammation present in the human bone marrow. Freshly isolated human mononuclear bone marrow cells and marrow stromal cell cultures produced PAF under calcium ionophore (2 microM) and LPS (10 micrograms/ml) stimulation. By contrast, M-CSF (1000 U/ml), GM-CSF (100 ng/ml), IL1, IL3, IL6 and stem cell factor (10 ng/ml) did not stimulate PAF production. Marrow stromal cells produced 50-fold more PAF than freshly isolated mononuclear marrow cells, suggesting that stromal cells might be the major source of the human marrow-derived PAF. Mononuclear marrow cells and stromal cell cultures metabolized PAF with 1-alkyl-2-acyl-glycerophosphocholine as the major metabolic product. PMSF and p-BPB decreased the catabolism of PAF by freshly isolated marrow cells, but not by stromal cell cultures. While stromal cells rather than haematopoietic progenitors might be a major source of the human bone-marrow-derived PAF, both cell types metabolize it, suggesting their putative role in the regulation of PAF concentration in the human bone marrow.

PAF and haematopoiesis. X. Macrophage colony-stimulating factor and granulocyte macrophage colony-stimulating factor enhance platelet-activating factor acetylhydrolase production by human blood-derived macrophages

Platelet-activating factor (PAF), a phospholipid autacoid with potent regulatory functions, is synthesized by stimulated monocytes. Macrophages are a source of the plasma acetylhydrolase activity (AHA) which regulates PAF concentrations. Granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage colony-stimulating factor (M-CSF) are involved in the differentiation and functions of cells from the monocytic/macrophagic lineage. This work reports that M-CSF and GM-CSF stimulated AHA production by human blood monocyte-derived macrophages in a time- and dose-dependent manner. After 7 days of culture without serum, a 6- and 4-fold increase was found in cells treated with M-CSF (1000 U/ml) and GM-CSF (50 ng/ml), respectively. M-CSF (up to 1000 U/ml) and GM-CSF (up to 10 ng/ml) did not induce PAF production by human blood monocytes. While GM-CSF (10 ng/ml) and interleukin-1 (10 U/ml) stimulated M-CSF production from monocyte-derived macrophages, PAF did not. These results indicate that M-CSF and GM-CSF enhance AHA production by human blood-derived macrophages cultured in low serum concentrations. Clearly the effects of growth factors on AHA production in vivo deserve to be assessed.

Serum factor from diabetic patients with or without retinopathy stimulates superoxide anion production by normal polymorphonuclear leukocytes

Oxygen free radicals (OFRs) have been implicated in the pathogenesis of diabetic microangiopathy. The effects of serum from insulin-dependent diabetes mellitus patients with or without retinopathy on the production of superoxide anion by normal polymorphonuclear leukocytes (PMNs) were measured spectrophotometrically and compared with that of age matched controls. Superoxide anion production by PMNs incubated with serum from retinopathy-free patients or patients with retinopathy was significantly higher than that of controls (P=0.0002 and 0.0001, respectively). Furthermore, superoxide anion production by PMNs incubated with serum from patients with retinopathy was significantly higher than retinopathy-free patients (P=0.02). These observations suggest that a diabetic serum factor provoked a significant generation of superoxide anion in normal PMNs, a phenomenon found parallel to the presence of retinopathy, indicating that OFRs may play a role in the progression of diabetic retinopathy. The nature of this serum factor remains to be clarified.

Involvement of a serine protease in the synthesis of platelet-activating factor by endothelial cells stimulated by tumor necrosis factor-alpha or interleukin-1 alpha

It has been shown that production of platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) by endothelial cells (EC) stimulated with tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 alpha requires the synthesis of new proteins and is regulated by anti-proteinases. Here, we demonstrate that TNF-alpha and IL-1 alpha induce the expression by EC of a 34-kDa diisopropyl fluorophosphate-binding protein immunoprecipitated by an anti-human elastase antibody. This protein is released in the medium and cleaves the chromogenic substrate N-methoxysuccinyl- Ala-Ala-Pro-Val p-anilide, which is specific for elastase. The generation of this elastase-like protein seems to be important for the synthesis of PAF induced by TNF-alpha and IL-1 alpha, as suggested by the following observations: (a) it precedes the synthesis of PAF; (b) the inhibitors of serine protease and anti-human elastase antibody prevent the synthesis of PAF and the activation of 1-O-alkyl-2-lyso-glycerophosphocholine acetyl-CoA: acetyltransferase, which is a key enzyme of the PAF remodelling pathway; (c) elastase, at concentrations similar to that detectable in the medium of cytokine-activated EC, elicits a rapid synthesis of PAF by EC. High-performance liquid chromatography-tandem mass spectrometric analysis of bioactive PAF demonstrates that the molecular species produced after stimulation of EC with TNF-alpha, IL-1 alpha or elastase are similar, with a predominant synthesis of the alkyl species. These results indicate that TNF-alpha and IL-1 alpha stimulate the production of a serine protease which is critical in the activation of enzymes involved in PAF synthesis, suggesting the potential involvement of this mechanism in the regulation of EC functions.

A dose intensity study of FLAC (5-fluorouracil, leucovorin, doxorubicin, cyclophosphamide) chemotherapy and Escherichia coli-derived granulocyte-macrophage colony-stimulating factor (GM-CSF) in advanced breast cancer patients

BACKGROUND

It has been demonstrated that granulocyte-macrophage colony-stimulating factor (GM-CSF) can ameliorate chemotherapy-induced neutropenia. The extent to which GM-CSF can increase the actual delivered dose intensity of combination chemotherapy over multiple cycles of therapy to patients with advanced breast cancer has not been well defined. We conducted a phase I/II study of dose-intensive FLAC chemotherapy (5-fluorouracil, leucovorin, doxorubicin, cyclophosphamide) in combination with GM-CSF in patients with locally advanced and metastatic breast cancer to study the acute and cumulative toxicities, anti-tumor activity and dose-intensity achievable with this regimen.

METHODS

Eighty-one patients with newly diagnosed stages IIB, III and IV breast cancer who were previously untreated with chemotherapy and who had measurable disease received multiple cycles of FLAC chemotherapy plus E. coli-derived GM-CSF administered every three weeks.

RESULTS

FLAC plus GM-CSF as associated with significant cumulative hematologic toxicity. Ninety-eight percent of patients developed grade 4 neutropenia; 29% of all cycles administered required hospitalization for fever and neutropenia; 41% and 22% of cycles required red blood cell and platelet transfusions, respectively. Other significant toxicities with E. coli-derived GM-CSF included mild to moderate first dose effects (hypotension, dyspnea, abdominal cramping) in 30% of patients; late occurring anaphylactoid reactions in 11% of patients; and vascular thromboses. The average delivered dose intensities over all cycles were cyclophosphamide, 210 mg/m2/week; doxorubicin, 14.8 mg/m2/week and 5-fluorouracil, 342 mg/m2/week. The overall clinical response rates were 100% and 83% for LABC and metastatic patients, respectively. There were 23% (6/26) pathologic CR's in the LABC patients given neoadjuvant FLAC and 22% (12/54) clinical CR's in the stage IV patients. The median survival of the LABC patients has not been reached (> 26 months) and is 30 months for the stage IV patients.

CONCLUSIONS

The administration of multiple cycles of FLAC plus E. coli-derived GM-CSF therapy is associated with cumulative, dose-limiting myelosuppression, especially thrombocytopenia, as well as significant clinical toxicity. A modest increase in FLAC dose intensity over the starting doses was achievable with the addition of GM-CSF. FLAC chemotherapy has substantial antitumor activity in the treatment of advanced breast cancer. The potential usefulness of FLAC plus GM-CSF must be balanced by its considerable cost and alteration in patients' quality of life due to toxicity. Combination hematopoietic growth factor strategies may be able to reduce the toxicity of FLAC and to allow further increase dose intensity.

Autocrine enhancement of leukotriene synthesis by endogenous leukotriene B4 and platelet-activating factor in human neutrophils

1. Platelet-activating factor (PAF) and leukotriene B4 (LTB4), two potent lipid mediators synthesized by activated neutrophils, are known to stimulate several neutrophil functional responses. In this study, we have determined that endogenous LTB4 and PAF exert autocrine effects on LT synthesis, as well as the underlying mechanism involved. 2. Pretreatment of neutrophils with either pertussis toxin (PT), or with receptor antagonists for LTB4 and PAF, resulted in an inhibition of LT synthesis induced by calcium ionophore, A23187. This inhibition was most marked at submaximal (100-300 nM) A23187 concentrations, whilst it was least at ionophore concentrations which induce maximal LT synthesis (1-3 microM). Thus newly-synthesized PAF and LTB4 can enhance LT synthesis induced by A23187 under conditions where the LT-generating system is not fully activated. 3. In recombinant human (rh) granulocyte-macrophage colony-stimulating factor (GM-CSF)-primed neutrophils, LT synthesis in response to chemoattractants (fMet-Leu-Phe or rhC5a) was also significantly inhibited by the LTB4 receptor antagonist, and to a lesser extent by PAF receptor antagonists. 4. Further investigation revealed that LTB4 and/or PAF exert their effects on LT synthesis via an effect on arachidonic acid (AA) availability, as opposed to 5-lipoxygenase (5-LO) activation. Indeed, the receptor antagonists, as well as PT, inhibited LT synthesis and AA release to a similar extent, whereas 5-LO activation (assessed with an exogenous 5-LO substrate) was virtually unaffected under the same conditions. Accordingly, we showed that addition of exogenous LTB4 could enhance AA availability in response to chemoattractant challenge in rhGM-CSF-primed cells, without significantly affecting the 5-LO activation status. Our data show that newly-generated PAF and LTB4 have the ability to positively feedback on LT synthesis by acting at the level of the phospholipase A2/re-esterification component of the LT biosynthetic pathway in neutrophils. Such autocrine affects are likely to represent an important amplification step of LT synthesis, and may as such contribute to the rapid onset, as well as to the evolution, of inflammatory responses.

Impaired superoxide anion, platelet-activating factor, and leukotriene B4 synthesis by neutrophils in cirrhosis

BACKGROUND

Several alterations of polymorphonuclear leukocyte (PMN) function were found in alcoholic cirrhotics that may contribute to augmented susceptibility to infections. We evaluated function and synthesis of lipid mediators in PMN obtained from nonalcoholic cirrhotics.

METHODS

We evaluated the phagocytic and chemotactic response together with superoxide anion (O2-), leukotriene B4, (LTB4) and platelet-activating factor (PAF) production in response to different stimuli in PMN from nonalcoholic cirrhotics as compared with controls.

RESULTS

PMN from cirrhotics showed, after stimulation with opsonized zymosan (STZ) and phorbol-12-myristate-13-acetate, a reduced capacity to produce O2- when compared with controls. [3H]acetate incorporation into PAF was significantly higher in PMN obtained from controls in respect to cirrhotics. Gas chromatography/mass spectrometry analysis confirmed a reduced PAF synthesis by PMN obtained from cirrhotics. LTB4 production from PMN, after stimulation with calcium ionophore (A23187) and STZ, was significantly reduced in cirrhotics. [3H]arachidonic acid release from prelabeled PMN, measured upon stimulation with A23187 and STZ, was higher in controls than in cirrhotics.

CONCLUSIONS

An altered synthesis of LTB4 and PAF is associated with an impaired O2- production by PMN in nonalcoholic cirrhosis. Reduced synthesis of lipid mediators may be related to an altered phospholipase A, activity.

Upregulatory effects of cefpimizole natrium on human leukocytes

Cefpimizole natrium (CPIZ), an antibiotic belonging to the cephalosporins, was examined regarding its influence on neutrophil functions. Neutrophil superoxide (O2-) generation increased by intravenous CPIZ in patients with maxillofacial diseases. In vitro examination revealed that CPIZ directly stimulates neutrophils to generate O2- in a dose-dependent manner, though the induction ability is not as strong as phorbol myristate acetate (PMA). Protein kinase C (PKC) activity in the neutrophil plasma membrane increased after CPIZ treatment, while the activity in the cytosol fraction decreased. CPIZ cooperated with biological response modifiers (BRMs) such as sizofilan, lentinan, OK-432, rIL-2 and rIFN-gamma in neutrophil O2- generation. Non-specific cytotoxicity against K562 cells and candida cells was also enhanced by neutrophil pretreatment with both CPIZ and one of the BRMs except for sizofilan and rIL-2. From these results it can be concluded that CPIZ directly enhanced neutrophil O2- generation and that these CPIZ activations are further beneficial to protection against bacterial infections.

Hemopoietic growth factors: a review

The hemopoietic growth factors are peptide hormones that are known to be responsible for the in vitro and in vivo proliferation of bone marrow progenitor cells into mature differentiated cells. These cytokines have had a major impact on the management of patients with cytopenias and have been extensively used as an adjunct to the management of patients with hematologic malignancies, with or without prior intensive chemotherapy. Other potential uses, being rigorously studied, include the potential mobilization of stem cells as well as recruitment phase-specific cells into the cell cycle, thus providing a more sensitive environment for targeting specific chemotherapeutic agents.