Effects of recombinant human granulocyte colony-stimulating factor on neutrophil functions in aged animals

We have studied the effects of recombinant human granulocyte colony-stimulating factor (rG-CSF) on granulopoiesis and neutrophil functions in aged rats and aged mice. We subcutaneously injected rG-CSF or control vehicle into aged rats (22 months old and 25 months old) for 7 consecutive days, counted the peripheral neutrophils and evaluated the functions of neutrophils isolated from venous blood. The peripheral neutrophil count in aged rats tended to be increased as compared with that in young rats (11 weeks old). However, the neutrophils in aged rats exhibited a decline of superoxide anion (O2-) release and phagocytic activity as compared with young rats. The peripheral neutrophil count in aged rats was significantly increased 5-6-fold as many as the control value by rG-CSF treatment, which was accompanied by a significant enhancement of O2- release and of phagocytic activity being restored to normal levels or better. In another series of experiments, we subcutaneously injected rG-CSF or control vehicle into aged mice (24-28 months old) or young mice (8 weeks old) for 7 consecutive days, and evaluated the functions of neutrophils isolated from peritoneal cavity. The peritoneal exudate neutrophils from the aged mice exhibited a decline of phagocytic and chemotactic activity as compared with the young mice. These functions in both young and aged mice were significantly enhanced by rG-CSF-treatment, and these functions in rG-CSF-treated aged mice were restored to a level higher than the level in control young mice. These findings demonstrate that rG-CSF is capable of enhancing granulopoiesis and restoring the age-related decline of neutrophil functions.     

Intestinal microvascular exchange in the rat during luminal perfusion with formyl-methionyl-leucyl-phenylalanine

Formyl-methionyl-leucyl-phenylalanine (FMLP), a peptide released from bacteria in the gut lumen, is known to both attract and activate neutrophils. The aim of this study was to determine whether luminal perfusion with 1 microM FMLP alters microvascular permeability, blood flow, and neutrophil migration in the small intestine of control rats and rats treated with antineutrophil serum. Microvascular permeability to total plasma proteins was determined from an analysis of lymphatic protein fluxes. Myeloperoxidase activity was used as an index of tissue neutrophil count. Intestinal blood flow was measured using radiolabeled microspheres and the reference blood sample method. In control rats, luminal perfusion with FMLP caused significant increases in blood flow, lymph flow, lymph protein clearance, and microvascular permeability, but it did not alter tissue myeloperoxidase activity. In rats treated with antineutrophil serum, tissue myeloperoxidase levels were reduced by approximately 55%, and the FMLP-induced changes in lymph flow, lymph protein clearance, and microvascular permeability were significantly attenuated. In vitro experiments with isolated rat neutrophils revealed that 1 microM FMLP elicits significant chemotaxis and degranulation yet minimally enhances superoxide production. The results of this study indicate that peptides produced by microorganisms in the gut lumen can increase intestinal microvascular permeability. The FMLP-induced alterations in microvascular exchange appear to be mediated by activated neutrophils.     

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

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

Effects of recombinant human granulocyte colony-stimulating factor on the mice receiving bone marrow transplantation following lethal irradiation: acceleration of recovery of the peripheral blood neutrophils and potentiation of anti-Pseudomonas resistance.

The effects of recombinant human granulocyte colony-stimulating factor (rG-CSF) on the recovery of peripheral blood neutrophil counts and resistance to i.p. infection by Pseudomonas aeruginosa were studied using a mouse bone marrow transplantation (BMT) model. A severe neutropenic period continued in the BMT mice for greater than 9 days following BMT. In contrast, the number of peripheral blood neutrophils in the BMT mice that received a daily administration of 2.5 micrograms of rG-CSF following BMT returned to normal by day 9. Thus, rG-CSF accelerated the recovery of the peripheral blood neutrophil counts in BMT mice. Anti-Pseudomonas resistance of the control BMT mice examined on days 7, 9, and 11 following BMT was one fifteenth to one fiftieth of normal mice, as indicated by the LD50 value. The anti-Pseudomonas resistance was elevated six- to sevenfold by the rG-CSF treatment. A marked increase in the neutrophils exudating into the peritoneal cavity in response to casein injection was observed in the rG-CSF-treated BMT mice. In addition, the reduced superoxide generative and phagocytic activity of the peritoneal neutrophils of the BMT mice were restored to normal by the rG-CSF treatment. It is suggested that rG-CSF potentiated anti-Pseudomonas resistance of the BMT mice by increasing neutrophils migrating to the infection site and restoring their functions; this may result from a prompt recovery of the peripheral blood neutrophil level together with the effect on neutrophil functions. These results indicate the clinical usefulness of rG-CSF in applications for BMT.     

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

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

Matrix metalloproteinase-9 release from human leukocytes.

Although proteinases are thought to contribute to the pathogenesis of bronchial asthma and COPD, the mechanism of proteinase release from inflammatory cells has not been thoroughly clarified. We examined matrix metalloproteinase (MMP-9) release from human leukocytes using soluble agonists such as C5a, FMLP, and PAF. Mononuclear cells, neutrophils, and eosinophils isolated from human leukocytes were incubated with C5a, FMLP, or PAF for 20 min. MMP-9 in supernatants was measured by ELISA. Among mononuclear cells, neutrophils, and eosinophils, MMP-9 was released mainly from neutrophils. FMLP was the most effective stimulus of MMP-9 release from neutrophils among three agonists: C5a, FMLP, and PAF. GM-CSF clearly enhanced FMLP-induced MMP-9 release. Pretreatment of neutrophils with pertussis toxin (PTX) resulted in the inhibition of FMLP-induced MMP-9 release, indicating the contribution of PTX-sensitive G-proteins to intracellular signal transduction in FMLP-induced MMP-9 release. These results suggest that neutrophils release large amounts of MMP-9 in response to FMLP, which is a bacterial product analogue. It cannot be excluded that MMP-9 released from neutrophils may be involved in the pathogenesis of bronchial asthma and COPD.     

In vivo activation of human neutrophil functions by administration of recombinant human granulocyte colony-stimulating factor in patients with malignant lymphoma

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) was administered (50 to 800 micrograms/m2) once daily as a half-hour intravenous (IV) infusion for 14 days to seven patients with malignant lymphoma. In all patients, administration of rhG-CSF not only ameliorated the decrease in absolute neutrophil count after the cytotoxic chemotherapy but also enhanced superoxide (O2-) release in neutrophils stimulated by N-formyl-methionyl-leucyl-phenylalanine (FMLP). The priming effect of rhG-CSF on neutrophil O2- release was rapid (evident within 6.5 hours) and sustained at least for 24 hours after a single IV administration of rhG-CSF. The responsiveness to further in vitro challenge of rhG-CSF was lost or reduced in neutrophils isolated after rhG-CSF treatment, indicating that neutrophils already primed in vivo by rhG-CSF are desensitized to this factor. In contrast to the results obtained with FMLP, when phorbol myristate acetate (PMA) was used as stimulus, no consistent enhancement of O2- release was observed, suggesting that rhG-CSF modulates the signal transduction pathways linked to FMLP receptors rather than increases the components of the O2- producing enzyme complexes. Administration of rhG-CSF also rapidly (evident within 15 minutes) caused an increase in expression of neutrophil C3bi-receptors that was sustained for at least 24 hours after a single IV administration of rhG- CSF. Pharmacokinetic study of rhG-CSF showed a half-life (t1/2) of 114 min. These findings show that rhG-CSF is a potent activator for neutrophil functions both in vivo and in vitro.     

Neuropeptides and inflammation. A somatostatin analog as a selective antagonist of neutrophil activation by substance P.

OBJECTIVE. Substance P and somatostatin are neuropeptides found in peripheral sensory nerves. In vitro, these have opposing effects on inflammatory cells. We compared the effects of these peptides on the activation of neutrophils. METHODS. Neutrophils were isolated from healthy volunteers, and chemotaxis, superoxide anion generation, aggregation, and changes in cytosolic calcium and GTPase activity were measured in the presence of substance P, somatostatin, and the chemoattractant FMLP. RESULTS. Substance P was an effective chemoattractant, 20% as potent as FMLP at equimolar concentrations. Substance P also stimulated GTPase activity in neutrophil plasma membranes. Somatostatin did not activate neutrophils; however, it effectively inhibited neutrophil chemotaxis and GTPase activity provoked by substance P, but not by FMLP. CONCLUSIONS. These studies demonstrate that substance P can effectively stimulate chemotaxis, possibly via effects on a GTP-binding protein distinct from that triggered by FMLP, and that somatostatin is a selective antagonist of substance P. The biochemical specificities of these peptides on cells may modulate neurogenic inflammation at the local level.     

Ca2+ response in neutrophils after exposure to bacterial N-formyl-methionyl-leucyl-phenylalanine: delayed response in ulcerative colitis

OBJECTIVE: In acute stages of ulcerative colitis (UC), neutrophils migrate from the circulation into inflamed colonic tissue, initiated by yet unknown stimuli. The bacterial peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP) is a component of the surface membrane of colonic bacteria such as Escherichia coli and stimulates Ca2+ influx into neutrophils, reflecting the fact that ionized calcium is an important secondary messenger for several neutrophil functions, including locomotion, phagocytosis and free oxygen radical production. Recent studies have revealed that Ca2+ dependent ICAM-1/beta 2-integrin mediated neutrophil migration is impaired in UC patients. The aim of the present work was to study the influx of Ca2+ into peripheral blood neutrophils of UC patients after exposure to FMLP and after binding of either beta 2-integrins or intercellular adhesion molecule-1 (ICAM-1). METHODS: The relative intracellular Ca2+ levels ([Ca2+]i ) were measured spectrofluorometrically in neutrophils isolated from eight UC patients and eight controls. The cells were exposed to 1 nm FMLP, 5 pm free ICAM-1, or antibodies binding ICAM-1 or the beta 2-integrins CD11a, CD11b, CD11c and CD18. RESULTS: A pronounced increase in [Ca2+]i was observed by exposure of cells to FMLP, and neutrophils from UC patients showed a consistent and significant delayed response as compared to cells from control subjects (P < 0.01). Antibody mediated cross-linking of CD18 triggered a small but detectable increase in [Ca2+]i, which did not differ between patients and controls. CONCLUSION: A delayed response to bacterial peptides appears to be a phenotypic trait for neutrophils of UC patients. A connection between FMLP stimulated Ca2+ influx and CD11/CD18 upregulation is discussed.     

Role of the neutrophil in oral disease: receptor deficiency in leukocytes from patients with juvenile periodontitis

In many diseases in which cellular abnormalities of neutrophil locomotion are found, patients have oral complications. Localized juvenile periodontitis (LJP) is used as an example of a severe periodontal disease that is related to compromised neutrophil function. Studies of chemotaxis and binding of LJP neutrophils in response to chemotactic factors N-formylmethionylleucylphenylalanine (FMLP), a structural analogue of a bacterial product, and complement fragment C5a were carried out to identify the molecular basis of the compromised neutrophil function. The rate of chemotaxis in LJP neutrophils was significantly lower than that of control neutrophils, and LJP neutrophils demonstrated fewer binding sites for these chemotactic factors than did normal neutrophils. The respective numbers of binding sites for FMLP on LJP neutrophils and normal neutrophils were 9,200 and 20,000 and for C5a were 133,000 and 218,000. However, for both chemotactic substances, the dissociation constants for LJP and normal neutrophils were similar. The expression of FMLP receptors was altered in LJP neutrophils, but no modulation abnormality was noted for the C5a receptor.     

Neuropeptides and inflammation. A somatostatin analog as a selective antagonist of neutrophil activation by substance P

Objective. Substance P and somatostatin are neuropeptides found in peripheral sensory nerves. In vitro, these have opposing effects on inflammatory cells. We compared the effects of these peptides on the activation of neutrophils. Methods. Neutrophils were isolated from healthy volunteers, and chemotaxis, superoxide anion generation, aggregation, and changes in cytosolic calcium and GTPase activity were measured in the presence of substance P, somatostatin, and the chemoattractant FMLP. Results. Substance P was an effective chemoattractant, 20% as potent as FMLP at equimolar concentrations. Substance P also stimulated GTPase activity in neutrophil plasma membranes. Somatostatin did not activate neutrophils; however, it effectively inhibited neutrophil chemotaxis and GTPase activity provoked substance P, but not by FMLP. Conclusions. These studies demonstrate that substance P can effectively stimulate chemotaxis, possible via effects on a GTP-binding protein distinct from that triggered by FMLP, and that somatostatin is a selective antagonist of substance P. The biochemical specificities of these peptides on cells may modulate neurogenic inflammation at the local level.     

Effects of obstructive jaundice on neutrophil production and acquisition of chemotactic activity in the bone marrow

Background and Aims:  Increased numbers and enhanced functions of peripheral neutrophils have been observed in obstructive jaundice. However, the effects of obstructive jaundice on the bone marrow, that is neutrophil production and acquisition of neutrophil chemotactic activity, have been poorly understood. In the present study, differentials of bone marrow cells and chemotactic activity of bone marrow neutrophils were evaluated in bile duct-obstructed rats.
Methods:  Male Wistar rats underwent either bile duct obstruction for 10 days or bile duct obstruction for 4 days followed by 6 days' internal biliary drainage. Differentials of peripheral blood and bone marrow cells were sequentially determined. Chemotactic activity of peripheral and bone marrow neutrophils was evaluated with a modified Boyden method using interleukin-8 (recombinant rat Gro-β) as a chemoattractant.
Results:  Numbers of peripheral neutrophils significantly increased after bile duct obstruction. Significant increases in the myeloid/erythroid (M/E) ratio of bone marrow cells were observed after bile duct obstruction. The neutrophil proliferative pool (promyelocytes and myelocytes) increased initially, followed by an increased neutrophil storage pool (metamyelocytes, bands, and segmented neutrophils). The M/E ratio as well as the neutrophil proliferative and storage pools normalized after internal biliary drainage. Chemotactic activity was enhanced in both peripheral and bone marrow neutrophils after bile duct obstruction, and enhanced chemotaxis was alleviated with internal biliary drainage.
Conclusion:  The present results strongly suggest the principal role of the bone marrow in increasing the number of neutrophils and their chemotactic activity during obstructive jaundice.     

In vitro inhibition of interleukin-2-induced defective polymorphonuclear chemotaxis by TNF inhibitor

Abstract: Patients undergoing immunotherapy with interleukin-2 experience multiple side effects and are highly susceptible to bacteremia. In a previous study, we confirmed that a profound deficiency of neutrophil chemotaxis is induced by interleukin-2 therapy. Migration in response to N-formyl-methionyl-leucyl-phenylalanine (FMLP), being normal before therapy, was markedly impaired after the first cycle and further decreased after the third cycle of treatment. A direct effect of interleukin-2 on neutrophil chemotaxis is controversial. However, peripheral blood cells exposed to interleukin-2 secrete secondary cytokines. In particular, the release of tumor necrosis factor after interleukin-2 injection has been proposed as an important regulatory mechanism. When testing random migration and chemotaxis of neutrophils from normal subjects after incubation with the serum from treated patients, we found that this serum induced a defective chemotaxis similar to that of neutrophils from interleukin-2-treated patients. In order to assess the influence of tumor necrosis factor, we tested the effect of anti-tumor necrosis factor-alpha antibody on the chemotactic response of cells after incubation with the serum, and we observed a dose-dependent reduction of neutrophil chemotaxis deficiency. These data suggest that TNF is counteracting the neutrophil chemotactic deficiency observed during IL-2 treatment.     

Human neutrophil functions in obstructive jaundice

BACKGROUND/AIMS: The effect of obstructive jaundice on neutrophil function has not been extensively studied. Therefore, the present study aimed at evaluating the effect of obstructive jaundice on human neutrophils. METHODOLOGY: Twelve patients with obstructive jaundice due to common bile duct obstruction underwent endoscopic biliary drainage. Neutrophil functions (chemotaxis and superoxide anion generation) were evaluated before and 7 days after drainage. RESULTS: Neutrophil chemotaxis in response to FMLP (formyl-methionyl-leucyl-phenylalanine) or interleukin-8 was abnormally increased before drainage, and was normalized after drainage. Similarly, enhanced superoxide anion generation in response to FMLP or phorbol myristate acetate before drainage was alleviated after drainage. CONCLUSIONS: The results suggest neutrophil overactivity in patients with obstructive jaundice. The ameliorating effect of biliary drainage on neutrophil overactivity might play a role in the prevention of postoperative complications.     

Neutrophil function in normal and Chediak-Higashi syndrome cats following administration of recombinant canine granulocyte colony-stimulating factor.

The effects of recombinant canine granulocyte colony-stimulating factor (rcG-CSF) on leukocyte counts and neutrophil function in clinically normal cats and in cats heterozygotic and homozygotic for Chediak-Higashi syndrome (CHS) were examined. CHS is a genetic disease characterized by neutropenic episodes and defects in a variety of phagocyte functions. Short-term administration of rcG-CSF at 10 micrograms/kg body weight resulted in a five- to tenfold increase in circulating granulocytes by day 10 of administration and normalizes CHS neutrophil counts by day 3. The drug was specific for neutrophils as determined by differential cell counts. Neutrophil chemotaxis under agarose and phagocytosis of Escherichia coli were characterized following administration of rcG-CSF in vivo. Granulocytes elicited by rcG-CSF show enhanced chemotactic abilities toward activated serum, increased spontaneous migration, and an enhanced ability to ingest opsonized E. coli. At a concentration of 1 nM rcG-CSF in vitro, chemotaxis and spontaneous migration were increased, with no effect on phagocytosis. CHS neutrophil function was improved by administration of rcG-CSF in all parameters studied, although the defect in chemotaxis was present throughout the treatment period. We conclude from this study that neutrophils elicited by rcG-CSF are functionally enhanced and that rcG-CSF may be a viable therapy for CHS and other related disorders.     

A novel syndrome of severe neutrophil dysfunction: unresponsiveness confined to chemotaxin-induced functions

We have identified a patient with a number of neutrophil dysfunctions. The patient was a female baby who lived for 8 months. During her life, she developed severe bacterial infections and showed omphalitis, impaired wound healing, and a pronounced leukocytosis. She was not a patient with leukocyte adhesion deficiency, because all leukocyte CD18 complex proteins were expressed at normal levels. Yet, neutrophil polarization and chemotaxis to platelet-activating factor, leukotriene B4, or formyl-methionyl-leucyl-phenylalanine (FMLP) were completely absent. We found a strong defect in actin polymerization in response to chemotactic stimuli, but only a retarded or even normal reaction with other stimuli. This indicates that the cellular dysfunctions were not due to an intrinsic defect in actin metabolism. Instead, the regulation of actin polymerization with chemotactic stimuli seemed to be defective. We concentrated on FMLP-induced responses in the patient's neutrophils. Functions dependent on activation of complement receptor type 3, such as aggregation or adherence to endothelial cells, were normally induced. Binding to serum-coated coverslips was normal in cell number; however, spreading was not observed. Exocytosis from the specific granules was readily induced. In contrast, FMLP failed to induce a respiratory burst activity or degranulation of the azurophil granules. FMLP induced a normal increase in free intracellular Ca2+, but a decreased formation of diglycerides (especially the 1-O-alkyl,2- acyl compounds). Thus, we have described a patient whose neutrophils show a severe defect in functional activation via chemotaxin receptors, resulting in a selective absence of NADPH oxidase activity, exocytosis from the azurophil granules, and actin polymerization. Our findings show that actin polymerization for neutrophil spreading and locomotion is regulated differently from that for phagocytosis. Also, the release of azurophil and specific granule contents is clearly shown to be regulated in a different way.     

Comparative studies of microscopically determined aggregation, degranulation, and light transmission after chemotactic activation of adult and newborn neutrophils

Changes in the light transmission of suspensions of activated neutrophils are widely used to measure the dynamics of neutrophil aggregation. Such studies have suggested, for example, that aggregation is irreversible for human newborn neutrophils but fully reversible for adult cells. We have evaluated aggregation directly by microscopic particle counting and compared it with changes in light transmission (delta T) and with release from three granule subsets for neutrophils activated with N-formyl-methionyl-leucyl-phenylalanine (FMLP). Maximal increases in %T in response to 0.5 micromol/L FMLP were approximately 25% larger for newborn than for adult neutrophils, and were only partially reversible by 8 minutes, while %T increases for adult neutrophils were fully reversible. However, measurements of neutrophil aggregation using light microscopy showed that both newborn and adult neutrophils fully deaggregated. A further independence of delta T from aggregation was found by pretreating adult neutrophils with cytochalasin B (5 micrograms/mL) in the presence of 0.5% gelatin, a pretreatment that blocked FMLP-induced neutrophil aggregation while allowing large increases in %T and degranulation. In response to FMLP, newborn neutrophils released more enzyme from each granule subset than did adult neutrophils. Our results suggest that cellular events associated with neutrophil activation (other than aggregation) are implicated in light transmission responses and that these differ for adults and newborns. These results also suggest that reports of neutrophil aggregation should be based on direct particle counting methods rather than on %T responses.     

Rho-GTPase-dependent platelet-neutrophil interaction affected by HMG-CoA reductase inhibition with altered adenosine nucleotide release and function

Platelet activation and aggregation is considered a crucial step in the initiation and aggravation of arterial thrombosis. ADP from activated platelets is recognized as major factor in thrombus formation and is a potent stimulator of oxygen-free radical release from neutrophils. The aim of the present investigation was to determine in vitro the direct effects of statins on ATP and ADP secretion by platelets and its impact on subsequent oxidative burst activity in neutrophils. Human neutrophils and platelets were isolated from peripheral blood. Levels of platelet-derived ATP and ADP were measured by high-performance liquid chromatography, oxygen-free radical release of neutrophils was measured fluorometrically, and chemotaxis experiments were performed. Rho-GTPases were studied by Western blot analysis. Thrombin-activated platelets primed neutrophils for enhanced oxygen-free radical release on triggering with formyl-Met-Leu-Phe, reduced by cerivastatin and simvastatin treatment of platelets. The two statins decreased the amount of adenosine-derivative release in these cells. Rho-GTPases, required for the thrombin signaling in platelets and neutrophils, were decreased after coincubation with statins. Data demonstrate that inhibition of Rho-GTPases by statins inhibit platelet ADP and ATP release and the consecutive augmentation of neutrophil oxygen-free radical release. Statins affect platelet-neutrophil interactions by altering Rho-GTPase-dependent adenosine nucleotide function.     

Influence of biliary obstruction on neutrophil chemotaxis

The effect of obstructive jaundice on neutrophil chemotactic function was investigated, with a potent chemotactic factor, IL-8 (recombinant rat GRO-β), in rats that received 7-day bile duct ligation. Carrageenin or IL-8 was injected into a preformed air pouch, and exudate was collected 4 h later for measurement of myeloperoxidase activity. In vitro chemotaxis of peripheral neutrophils to IL-8 was evaluated by a modified Boyden chamber method. Both carrageenin and IL-8 induced significantly pronounced intra-air pouch neutrophil recruitment in the bile duct-ligated group compared with a sham-ligated group. In vitro neutrophil chemotaxis was significantly increased in the bile duct-ligated group compared with the sham-ligated group. The present experimental model suggests enhanced neutrophil chemotaxis to IL-8 in obstructive jaundice. (Received Sept. 10, 1997; accepted Jan. 23, 1998)     

Role of neutrophil and T cell functions in host defense mechanisms of the elderly]

We studied neutrophil functions (phagocytosis, intracellular killing and chemotaxis with or without recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) and T cell functions (lymphocyte proliferation and production of GM-CSF in response to phytohemagglutin (PHA)) to clarify host defense mechanisms in the elderly. There was no significant difference in phagocytic activity of neutrophils between the elderly and control young adults. rhGM-CSF enhanced phagocytosis by neutrophils, and a similar degree of enhancement was obtained in both groups. Killing activity of neutrophils evaluated by the new Nitroblue tetrazolium reduction test in the elderly was significantly lower than that in young adults (p < 0.001), however, pretreatment of neutrophils with rhGM-CSF resulted in an increase of killing activity in the elderly, raising their response to a level comparable to that of young adults pretreated with rhGM-CSF. There was no significant difference between the elderly and young adults in chemotaxis of neutrophils. rhGM-CSF alone did not prime chemotaxis, but primed chemotaxis in response to chemoattractant (N-formyl-methionyl-leucyl-phenylalanin) in both individuals. Lymphocyte proliferation and production of GM-CSF in response to PHA in the elderly were significantly lower than those in the young adults (p < 0.001, p < 0.05, respectively). These results indicated that impaired T cell functions may contribute, at least in part, to susceptibility to bacterial infection in the elderly.