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PubMed2000

[Rapidly progressive, refractory eosinophilia with a 250,000/microliter eosinophil count].

A 31-year-old man had received corticosteroids for 20 months for treatment of a brain tumor, and his blood eosinophil count ranged from 100/microliter to 1,000/microliter. On June 24th, 1998, he was re-admitted because of dyspnea secondary to left massive pleural effusion. Peripheral blood examination revealed an eosinophil count of 48,000/microliter. The eosinophils were hypersegmented, with abnormal distribution of eosinophilic granules and formation of cytoplasmic vacuoles. Blasts and basophils were not increased, hemoglobin was 13.4 g/dl, and the platelet count was 79,000/microliter. Bone marrow was slightly hypercellular with 55% eosinophils and 0.2% blasts. The patient's karyotype was normal, and Wilms' tumor gene was not detected. Serum IgE was normal and serum vitamin B12 and soluble IL-2 receptor were elevated. Serum levels of eosinophilopoietic cytokines, IL-3, IL-5, and GM-CSF, were low. Specimens of pleural fluid contained many eosinophils. Because the eosinophil count increased to 110,000/microliter on July 2nd, hydroxyurea was started without effect. On July 16th, the eosinophil count reached 167,000/microliter, and vincristine was added. The eosinophil count rose to 253,000/microliter the next day, and cytarabine and daunorubicin were administered, but the patient died of septic shock. Although the clinical course suggested eosinophilic leukemia, monoclonal proliferation of eosinophils was not demonstrated. To our knowledge, this is the highest peripheral blood eosinophil count reported in the literature to date.

Adult↗
PubMed1996

Human eosinophils express messenger RNA encoding RANTES and store and release biologically active RANTES protein.

Eosinophils synthesize and store various cytokines with potential autocrine activity. We hypothesized that eosinophils synthesize and store RANTES, a CC-chemokine with potent eosinophil chemotactic activity. Expression of RANTES mRNA in highly purified eosinophil populations was detected by reverse transcription followed by polymerase chain reaction analysis. In situ hybridization (ISH) with 35S-labeled RANTES-specific riboprobes showed that 6.8-10% of peripheral blood eosinophils obtained from atopic subjects expressed RANTES mRNA, increasing to 25% after incubation (16 h) with interferon (IFN)-gamma, but not ionomycin in vitro. Peripheral blood eosinophils also showed specific immunoreactivity with an anti-RANTES monoclonal antibody, consistent with translation of the mRNA. By enzyme-linked immunosorbent assay, blood eosinophils were shown to contain a median of 7300 pg (range 5200-8800) RANTES per 10(6) cells, of which a mean of 24% was released into culture supernatants after stimulation of the cells with serum-coated particles in vitro. These culture supernatants exhibited eosinophil chemotactic activity which was inhibited (mean 68%) by a specific anti-RANTES antibody. Sequential immunocytochemistry and ISH on biopsies obtained from allergen-induced late-phase cutaneous reactions showed that 55-75% of the infiltrating RANTES mRNA+ cells were EG2+ eosinophils. Allergen, but not diluent challenge, was also associated with a time-dependent increase in the number of cells showing RANTES immunoreactivity. Of these cells, 55% were identified as eosinophils by morphological criteria. Thus, human eosinophils have the capacity to synthesize, store and secrete physiologically relevant quantities of RANTES, and may therefore be an important source of this chemokine in allergic inflammation.

Allergens↗
PubMed1998

Airway eosinophilic inflammation and bronchial hyperresponsiveness after allergen inhalation challenge in asthma.

Allergen exposure in atopic asthmatic patients is associated with recruitment and activation of eosinophils in the airways. Once activated, eosinophils release toxic products, including the eosinophil cationic protein (ECP), able to damage bronchial structures and to increase bronchial hyperresponsiveness. With this background, the present study was designed to evaluate whether ECP levels in bronchoalveolar lavage (BAL) fluid could reflect, better than BAL eosinophil counts, the cellular activation that follows allergen exposure in atopic asthmatics. Twenty-two atopic patients attended the laboratory on two separate days. On the 1st day, they underwent methacholine (MCh) inhalation challenge to detect the degree of nonspecific bronchial hyperresponsiveness. On the 2nd day, they underwent fiberoptic bronchoscopy and BAL, at baseline or 4-6 h after allergen inhalation challenge. In this latter patient group, MCh challenge was repeated 3-5 h after allergen challenge, 1 h before fiberoptic bronchoscopy. The analysis of the mean baseline FEV1 values and the degree of bronchial reactivity to MCh (MCh Pd20) on the 1st study day did not demonstrate differences between the two patient groups (p > 0.1, each comparison). In addition, in the allergen-challenged group, MCh Pd20 was decreased significantly after allergen challenge (151.4 micrograms/ml and 67.6 micrograms/ml, respectively, before and after challenge; p < 0.05). Evaluation of the different BAL cell types demonstrated that the proportions of eosinophils and epithelial cells were increased significantly in the allergen-challenged group compared with the group evaluated at baseline (p < 0.01 and p < 0.05, respectively). Moreover, ECP levels, corrected by the correspondent albumin levels (ECP/Alb), were higher in the allergen-challenged group compared with the group evaluated at baseline (p < 0.05). In addition, although a positive correlation was demonstrated between BAL eosinophil percentages and ECP/Alb values (r = 0.72, p < 0.05) in the group evaluated at baseline, no links were found between these parameters in the allergen-challenged group (p > 0.1). However, in this latter group, a weak positive correlation was demonstrated between eosinophil percentages and delta Mch, i.e., the increased non-specific bronchial reactivity, which is observed after allergen challenge (r = 0.55; p < 0.05). Thus, in stable asthmatic patients an ongoing activation of eosinophils parallels their migration, but this eosinophilic inflammation is not strictly related to bronchial reactivity to Mch. By contrast, after allergen inhalation challenge, eosinophil recruitment and activation seem to follow different temporal kinetics, and eosinophilic inflammation may be partially associated with the degree of airway hyperresponsiveness.

Adolescent↗
PubMed1990

Migratory responses of eosinophil and neutrophil granulocytes from patients with asthma.

In the present study the migratory function of eosinophil and neutrophil granulocytes from patients with asthma were investigated. Fifty-seven patients with asthmatic disease of varying severity were included. Eosinophil and neutrophil chemotactic responses to 5% pooled normal human serum (NHS), 5% allergen-challenge serum, 2.5% zymosan-activated serum, N-formyl-methionyl-leucyl-phenylalanine (10 nmol/L), chemokinetic responses to albumin (2 gm/L) and 5% NHS, and the eosinophil and neutrophil chemotactic and chemokinetic activities of serum were investigated. Eosinophils from patients with asthma demonstrated significantly (p less than 0.02) increased chemotactic responses to allergen-challenge serum, zymosan-activated serum, and N-formyl-methionyl-leucyl-phenylalanine, compared with eosinophils from references. The chemokinetic responses to albumin and NHS were increased (p less than 0.01) by eosinophils from the patients who had blood eosinophilia (greater than 400 X 10(6)/L). Sera from the patients with asthma demonstrated raised eosinophil chemotactic activity (p less than 0.001) and raised eosinophil and neutrophil chemokinetic activity (p less than 0.001). The eosinophil chemokinetic activity of serum was correlated to the relative peak expiratory flow rate of the patients (r = -0.43; p less than 0.02). The increased migratory responses were specific for the eosinophils, since the migratory responses of their neutrophils were not altered compared with that of the references. These results suggest that the eosinophils from the patients with asthma had been exposed to a priming mechanism in vivo.

Adolescent↗
PubMed1991

Blood eosinophil number and activity in relation to lung function in patients with asthma and with eosinophilia.

Blood eosinophil count, serum concentrations of eosinophil cationic protein (ECP), eosinophil protein X (EPX), myeloperoxidase (MPO), and peak expiratory flow (PEF) rate were studied in 23 patients with severe labile asthma characterized by eosinophilia at the start and end of a treatment period of 5 weeks. The mean blood eosinophil count was 808 x 10(6)/L at the start of the treatment period. Serum ECP and EPX were significantly raised compared with that of the references, whereas the mean serum MPO level was normal. The mean PEF was significantly and negatively correlated to both blood eosinophil count and serum ECP and EPX, but the predominant correlation was that between blood eosinophil count and PEF. At the end of the treatment period, PEF had increased and the blood eosinophil count and serum ECP and EPX were reduced when these values were compared with the values at the start of the treatment period. There was a significant and negative correlation of mean PEF to serum ECP but not to the blood eosinophil count. In individual subjects, the decreases in the blood eosinophil counts and serum EPX were significantly correlated to the individual increases of mean PEF. In conclusion, the present investigation indicates that in patients with asthma and pronounced eosinophilia, the lung function of the patients was principally related to the number of circulating eosinophils, whereas, when their eosinophilia was reduced to moderate levels, the patient's lung function was closer related to the activity of the eosinophils.

Adolescent↗
PubMed2004

Eosinophil major basic protein: first identified natural heparanase-inhibiting protein.

BACKGROUND: Heparanase and eosinophils are involved in several diseases, including inflammation, cancer, and angiogenesis. OBJECTIVE: We sought to determine whether eosinophils produce active heparanase. METHODS: Human peripheral blood eosinophils were isolated by immunoselection and tested for heparanase protein (immunocytochemistry, Western blot), mRNA (RT-PCR) and activity (Na(2)[(35)S]O(4)-labeled extracellular matrix degradation) before and after activation. Heparanase intracellular localization (confocal laser microscopy) and ability to bind to eosinophil major basic protein (MBP) were also evaluated (immunoprecipitation). A model of allergic peritonitis resulting in eosinophilia was induced in TNF knockout and wild-type mice for in vivo studies. RESULTS: Eosinophils synthesized heparanase mRNA and contained heparanase in the active (50-kd) and latent (65-kd) forms. Heparanase partially co-localized with and was bound to MBP. No heparanase enzymatic activity was detected in eosinophils resting or activated with various agonists, including GM-CSF/C5a. Eosinophil lysates and MBP inhibited recombinant heparanase activity in a concentration-dependent manner (100%, 2 x 10(-7) mol/L). Eosinophil peroxidase and eosinophil cationic protein, but not myelin basic protein or compound 48/80, partially inhibited heparanase activity. Poly-l-arginine at very high concentrations caused an almost complete inhibition. In allergic peritonitis, heparanase activity in the peritoneal fluid inversely correlated with eosinophil number. CONCLUSIONS: MBP is the first identified natural heparanase-inhibiting protein. Its presence in the eosinophil granules might indicate a protective function of these cells in diseases associated with inflammation and cancer progression.

Animals↗
PubMed2005

Effects of the very late adhesion molecule 4 antagonist WAY103 on human peripheral blood eosinophil vascular cell adhesion molecule 1-dependent functions.

BACKGROUND: Eosinophil infiltration to the lung in allergic inflammation can be initiated by the tethering of circulating cells through very late adhesion molecule 4 (VLA-4; alpha4beta1, CD49d/CD29) to vascular cell adhesion molecule 1 (VCAM-1) expressed on pulmonary vascular endothelium. Small-molecule VLA-4 antagonists have been proposed as a therapeutic mechanism to prevent eosinophil infiltration in asthma; however, they might affect other eosinophil functions. OBJECTIVE: The small-molecule VLA-4 antagonist (2S)-3-(4-Dimethylcarbamoyloxyphenyl)-2-{[(4R)-5,5-dimethyl-3-(1-methyl-1H-pyrazole-4 sulfonyl)thiazolidine-4-carbonyl]amino}propionic acid (WAY103) was assessed for its effects on eosinophil VLA-4-dependent functions, including adhesion, migration, respiratory burst, and degranulation. METHODS: Human peripheral blood eosinophils were preincubated with WAY103, anti-alpha4, and/or anti-beta2 integrin mAbs and then assessed for adhesion to recombinant VCAM-1, intercellular adhesion molecule 1, and endothelial cell monolayers. Transmigration was measured by using human pulmonary microvascular endothelial cell monolayers and Transwell filters. Superoxide anion generation was determined by means of cytochrome C reduction and degranulation by means of eosinophil-derived neurotoxin release. RESULTS: WAY103 inhibition of eosinophil adhesion to recombinant VCAM-1 was dose dependent (63% inhibition with 100 nM WAY103, P < .04) and comparable with inhibition caused by anti-alpha4 mAb (60.1% inhibition). Although pretreatment with WAY103 also decreased eosinophil adhesion to TNF-alpha plus IL-4-activated human pulmonary microvascular endothelial cell monolayers, it did not prevent eosinophil transendothelial migration in response to RANTES. Finally, WAY103 inhibited VCAM-1-stimulated superoxide generation but enhanced cytokine-activated eosinophil-derived neurotoxin degranulation. CONCLUSION: Although small-molecule VLA-4 antagonists, such as WAY103, might reduce eosinophil adhesion, this approach might not be sufficient to eliminate this cell from in vivo allergic airway inflammatory participation and could even promote specific cell activation.

Adolescent↗
PubMed1993

Nasal tissue eosinophils in allergic rhinitis.

The density characteristics and functional heterogeneity of nasal tissue eosinophils were studied. The density distribution profiles of eosinophils from patients with allergic rhinitis (AR) showed peaks at densities of 1.068 to 1.084 g/ml, significantly lower than the densities of eosinophils in non-allergic patients with nasal polyps and chronic sinusitis (p < 0.01). The proportion of hypodense eosinophils in patients with AR was 43%; this was significantly greater than that in non-allergic subjects (p < 0.001). Patients with AR tended to have more EG2-positive tissue eosinophils. Furthermore, normodense eosinophils in nasal tissue tended to show a higher percentage of EG2-positive cells than hypodense eosinophils. On the other hand, circulating hypodense eosinophils showed a higher percentage of EG2-positive cells than normal density eosinophils. These results suggest that tissue eosinophils may be activated, and that the functional heterogeneity of eosinophils is dependent on factors other than cell density.

Adult↗
PubMed2004

Leukotriene D4 and eosinophil transendothelial migration, superoxide generation, and degranulation via beta2 integrin.

BACKGROUND: Evidence indicates that cysteinyl leukotriene (cysLT) 1 receptor antagonists possess anti-inflammatory properties in asthmatic patients in vivo. Although the exact mechanisms of these actions remain unknown, cysLTs regulate the locomotion and functions of eosinophils. We previously reported that leukotriene D4 augments the expression of eosinophil beta2 integrin and the adhesion of eosinophils to rh intercellular adhesion molecule 1 via beta2 integrin. OBJECTIVE: To examine whether leukotriene D4 modifies the transendothelial migration (TEM) and effector functions of eosinophils. METHODS: We evaluated the effects of leukotriene D4 on (1) eosinophil TEM across human umbilical vein endothelial cells, (2) superoxide anion (O2-) generation, and (3) eosinophil-derived neurotoxin release in eosinophils isolated from the blood of healthy individuals. RESULTS: Leukotriene D4 (0.1-1 microM) significantly induced eosinophil TEM, O2- generation, and eosinophil-derived neurotoxin release. Pranlukast, a cysLT1 receptor antagonist, significantly inhibited all of these parameters, although the inhibitory effect on O2- generation was partial. All of these responses were significantly inhibited by anti-beta2 integrin but not by anti-alpha4 integrin antibodies. CONCLUSIONS: Leukotriene D4 directly up-regulates the TEM and effector functions of eosinophils mainly via the cysLT1 receptor and beta2 integrin. These effects of leukotriene D4 probably contribute to the manifestation of eosinophil inflammation in asthmatic airways.

Adult↗
PubMed1999

Characterization of eosinophils and detection of eotaxin in skin chamber fluid after challenge with relevant allergen in patients with mild asthma.

BACKGROUND: A selective recruitment of eosinophils to sites of allergic inflammation is suggested to be controlled by regulation of cytokines, chemokines and adhesion molecules. OBJECTIVE: The aim of this study was to examine whether allergen challenge in skin chambers, applied on patients with allergic rhinitis and mild asthma, results in a selective influx of activated eosinophils and detectable levels of cytokines/chemokines related to eosinophil recruitment, such as interleukin (IL)-5 and eotaxin. METHODS: A skin blister was induced on the volar aspect of each forearm; one contained PBS-heparin buffer (control) and the other was challenged with relevant allergen. Peripheral blood was drawn before the allergen was applied to the skin chamber, and the expression of CD9, CD11b and EG2-epitope on intracellular eosinophil cationic protein (ECP) was analysed in eosinophils. Chamber fluid was collected 8 h after allergen application and analysed for differential cell counts, expression of eosinophil activity markers, the presence of ECP, eotaxin, and IL-5. RESULTS: The number of recruited leucocytes was equal in the allergen-challenged chambers and in controls. However, the number of eosinophils was significantly increased in the allergen-challenged chambers, and elevated levels of released ECP were measured. Moreover, the eosinophils recruited were activated, as shown by increased expression of EG2 and CD11b, and decreased expression of CD9, in comparison with blood eosinophils. In the skin chamber fluids, higher levels of eotaxin were detected in the allergen-challenged chambers than in controls, but there were no detectable levels of IL-5. CONCLUSION: We have demonstrated a selective recruitment of eosinophils, and higher levels of released ECP and eotaxin, in skin chambers stimulated with allergen, as compared with control chambers. Allergen challenge in skin chambers is a useful tool for studies of eosinophil recruitment, their state of activation, and their involvement in the allergic inflammatory response.

Adult↗
PubMed1992

RANTES and macrophage inflammatory protein 1 alpha induce the migration and activation of normal human eosinophil granulocytes.

The cellular infiltrates of certain inflammatory processes found in parasitic infection or in allergic diseases consist predominantly of eosinophilic granulocytes, often in association with activated T cells. This suggests the existence of chemotactic agonists specific for eosinophils and lymphocyte subsets devoid of neutrophil-activating properties. We therefore examined four members of the intercrine/chemokine superfamily of cytokines (monocyte chemotactic peptide 1 [MCP-1], RANTES, macrophage inflammatory protein 1 alpha [MIP-1 alpha], and MIP-1 beta), which do not activate neutrophils, for their ability to affect different eosinophil effector functions. RANTES strongly attracted normal human eosinophils by a chemotactic rather than a chemokinetic mechanism with a similar efficacy as the most potent chemotactic myeloid cell agonist, C5a. MIP-1 alpha also induced eosinophil migration, however, with lower efficacy. RANTES and MIP-1 alpha induced eosinophil cationic protein release in cytochalasin B-treated eosinophils, but did not promote leukotriene C4 formation by eosinophils, even after preincubation with interleukin 3 (IL-3), in contrast to other chemotactic agonists such as C5a and formyl-methionyl-leucyl-phenylalanine (FMLP). RANTES, but not MIP-1 alpha, induced a biphasic chemiluminescence response, however, of lower magnitude than C5a. RANTES and MIP-1 alpha both promoted identical transient changes in intracellular free calcium concentration ([Ca2+]i), with kinetics similar to those induced by chemotactic peptides known to interact with G protein-coupled receptors. No cross-desensitization towards other peptide agonists (e.g., C5a, IL-8, FMLP) was observed, suggesting the presence of specific receptors. Despite its weaker eosinophil-activating properties, MIP-1 alpha was at least 10 times more potent on a molar basis than RANTES at inducing [Ca2+]i changes. Interestingly, RANTES deactivated the MIP-1 alpha-induced [Ca2+]i changes, while the RANTES response was preserved after MIP-1 alpha stimulation. MCP-1, a potent monocyte chemoattractant and basophil agonist, as well as MIP-1 beta, a peptide with pronounced homology to MIP-1 alpha, did not activate the eosinophil functions tested. Our results indicate that RANTES and MIP-1 alpha are crucial mediators of inflammatory processes in which eosinophils predominate.

Blood Proteins↗
PubMed2026

IL-33 Drives Inflammatory Changes and Extracellular Trap Formation in Eosinophils Involving Oxidised LDL and Complement Pathways.

BACKGROUND: IL-33 levels are elevated in the airways of patients with eosinophilic diseases, and IL-33 receptor expression on eosinophils is upregulated in type 2-high environments. However, the role of IL-33 in the regulation of human eosinophils remains unclear. OBJECTIVE: To elucidate the inflammatory effects of IL-33 on the cellular function of human eosinophils. METHODS: Blood eosinophils were stimulated with IL-33, TNF-&#x3b1;, oxidised low-density lipoprotein (oxLDL) and complement fragments (C3a and C5a). Multi-omics analyses, including transcriptomics and proteomics, were performed. Extracellular trap formation (ETosis) was assessed by SYTOX nucleic acid staining and was visualised by immunofluorescence and transmission electron microscopy. RESULTS: Multi-omics analyses revealed an IL-33- and TNF-&#x3b1;-induced inflammatory gene signature characterised by the upregulation of cell surface markers (oxLDL receptor 1, CD22, CD4 and ICAM-1) and inflammatory mediators (C3, CCL3/4 and IL1A/B). CD22 upregulation was specific to IL-33 stimulation. Eosinophils derived from nasal polyps exhibited a gene expression profile similar to that of IL-33-stimulated eosinophils. Functional assays demonstrated that oxLDL and complement fragments differentially prolonged eosinophil survival and altered the expression of adhesion molecules. OxLDL- and complement fragment-induced gene signatures were partly detected in eosinophils derived from nasal polyps. Furthermore, IL-33 triggered ETosis via NADPH oxidase, mitogen-activated protein kinase and phosphoinositide 3-kinase pathways. CONCLUSIONS: IL-33, in conjunction with oxLDL and the complement cascade, induces inflammatory changes in eosinophils, promoting an ETosis-prone phenotype. These pathways represent potential therapeutic targets in refractory eosinophilic diseases.

Humans↗
PubMed1996

Eosinophil activity markers in peripheral blood have high predictive value for bronchial hyperreactivity in patients with suspected mild asthma.

The present study aimed to evaluate the predictive value of eosinophils and markers of their activity for bronchial hyperreactivity (BHR) in a population of patients with recently developed clinical symptoms of asthma. The activation of eosinophils was estimated by measuring eosinophil cationic protein (ECP) in serum. In addition, flow cytometry was used to measure the expression of the EG2-epitope on intracellular ECP in eosinophils from peripheral blood. Twenty-eight consecutive patients with clinical history of asthma were studied. Of the 28 patients, 18 had a positive bronchial challenge test measured as PD20 < or = 1600 micrograms histamine. A significantly higher concentration of eosinophils and a trend to higher ECP in the peripheral blood was found in the hyperreactive group than in the nonreactive group. However, the intracellular expression of ECP did not correlate with the PD20 value, and no significant difference between the groups was found. With one eosinophil activity marker, either serum ECP or EG2, BHR could be predicted in 70% of the patients. If we combined any two of the activity markers (serum ECP, EG2, or the percentage of eosinophils), the predictive value increased to 100%. We conclude that the blood eosinophil concentration, as well as, to some extent, serum ECP, has a high specificity for BHR in patients with recently developed clinical symptoms of asthma. Despite normal bronchial reactivity, some patients had signs of activated eosinophils, i.e., high serum ECP and increased EG2 expression. Thus, these markers may reflect early stages in the development of BHR. Our results also indicate that a combined evaluation of percentage of eosinophils and of eosinophil activity markers is of clinical value to predict BHR.

Adolescent↗
PubMed2000

Bcl-2 expression in sputum eosinophils in patients with acute asthma.

BACKGROUND: Eosinophils play a pivotal role in asthmatic airway inflammation. Apoptosis is thought to be critically relevant in promoting the clearance of inflammatory cells and the resolution of inflammation. Bcl-2 inhibits apoptosis in cellular systems. A study was undertaken to determine whether bcl-2 expression in sputum reflects the clinical severity of patients with asthma. The relationship between bcl-2 expression in sputum eosinophils and eosinophil activation markers such as interleukin (IL)-5 and eosinophil cationic protein (ECP) levels in sputum supernatant was evaluated. METHODS: Sputum was obtained from 18 patients with asthma. Fresh expectorated sputum separated from saliva was treated with an equal volume of dithiothreitol 0.1%, cytospun for cell differentials and bcl-2 stain, and the supernatant was collected for biochemical assay. Bcl-2+ eosinophils were stained using immunocytochemistry, ECP was measured by fluoroimmunoassay, and IL-5 was detected by sandwich enzyme linked immunosorbant assay. RESULTS: Twelve patients with severe or life threatening asthma had more bcl-2+ eosinophils (mean difference 46.8% (95% CI 27.0 to 66.6), p<0.01) and a higher ECP level (p<0.01) in the sputum than those with mild to moderate asthma (n = 6). IL-5 was frequently detected in patients with severe or life threatening asthma (11/12 versus 1/6, p<0.01). There was a significant positive correlation between bcl-2+ eosinophils and ECP levels (r = 0.61, p<0.01) and between bcl-2+ eosinophils and IL-5 levels (r = 0.83, p<0.01). There was a significant negative correlation between bcl-2+ eosinophils and FEV(1)/FVC (r = -0.54, p<0.05). CONCLUSION: The increased expression of bcl-2 in eosinophils from sputum of subjects with severe asthma suggests that bcl-2 may prolong survival and decrease apoptosis of airway eosinophils in asthma.

Acute Disease↗
PubMed2002

Adhesion-dependent interactions between eosinophils and cholinergic nerves.

Eosinophils adhere to airway cholinergic nerves and influence nerve cell function by releasing granule proteins onto inhibitory neuronal M(2) muscarinic receptors. This study investigated the mechanism of eosinophil degranulation by cholinergic nerves. Eosinophils were cocultured with IMR32 cholinergic nerve cells, and eosinophil peroxidase (EPO) or leukotriene C(4) (LTC(4)) release was measured. Coculture of eosinophils with nerves significantly increased EPO and LTC(4) release compared with eosinophils alone. IMR32 cells, like parasympathetic nerves, express the adhesion molecules vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 (ICAM-1). Inhibition of these adhesion molecules alone or in combination significantly inhibited eosinophil degranulation. IMR32 cells also significantly augmented the eosinophil degranulation produced by formyl-Met-Leu-Phe. Eosinophil adhesion to IMR32 cells resulted in an ICAM-1-mediated production of reactive oxygen species via a neuronal NADPH oxidase, inhibition of which significantly inhibited eosinophil degranulation. Additionally, eosinophil adhesion increased the release of ACh from IMR32 cells. These neuroinflammatory cell interactions may be relevant in a variety of inflammatory and neurological conditions.

Acetylcholine↗
PubMed2000

Involvement of eosinophils in the early-phase allergic reaction in a guinea pig rhinitis model.

BACKGROUND: Eosinophils are found in the nasal lavage fluid (NLF) and nasal biopsies of patients with allergic rhinitis after a nasal antigen challenge, and associated not only with a late-phase allergic reaction (LPR) but also an early phase allergic reaction (EPR). Numerous studies have been carried out to clarify the participation of eosinophils in LPR or airway hyperresponsiveness. However, there has been no published report describing in detail the role of eosinophils during EPR. To better understand the involvement of eosinophils in EPR, we studied the effects of repeated antigen challenges on nasal airway responsiveness and eosinophilic inflammation in EPR using a guinea pig rhinitis model. METHODS: Nasal airway responsiveness was measured as the nasal airway resistance (NAR) after nasal antigen provocation. Eosinophilic inflammation during EPR was assessed by nasal lavage and histopathological examination using two groups of animals: those in group 1 were subjected to a sensitization pretreatment only, and those in group 2 were subjected to a pretreatment of sensitization followed by repeated nasal challenges. RESULTS: Repeated antigen challenges induced nasal hyperresponsiveness as indicated by a decrease in the antigen provocation dose and a significant increase in NAR. Furthermore, significant increases in eosinophil counts, eosinophil peroxidase (EPO) activity and protein content in NLF during EPR were observed following antigen provocation in group 2. There were significant correlations between the levels of these parameters, and albumin was the most prevalent of the proteins in NLF. Histopathological examination showed that the degree of eosinophil infiltration into the lamina propria of the nasal mucosa of the animals in group 2 was significantly and apparently higher than in group 1. Particularly, epithelial disruption and mucosal edema were significantly elevated after antigen provocation in group 2. CONCLUSIONS: These results suggest that chronic eosinophil accumulation is induced by repeated antigen challenges in the nasal tissue, and that once antigen provocation occurs, eosinophils in the tissue are activated and responsible for the amplification of EPR such as vascular permeability and mucosal edema.

Animals↗
PubMed2004

German cockroach extract induces activation of human eosinophils to release cytotoxic inflammatory mediators.

BACKGROUND: Eosinophils play an important role in the pathogenesis of allergic diseases. Sensitization and exposure to cockroach allergen have been demonstrated to be one of the major risk factors for the development of bronchial asthma. However, little is known regarding the functional capacity of cockroach extract antigen to activate human eosinophils. OBJECTIVE: We investigated whether German cockroach extract can activate human eosinophils to release cytotoxic inflammatory mediators. METHODS: Purified eosinophils from the peripheral blood were incubated with various concentrations (0-200 microg/ml) of German cockroach extract antigen. Effector functions of eosinophils were checked by degranulation and superoxide anion production. In addition, we examined surface expression of CD11b and CD69, and intracellular activation of p38 mitogen-activated protein kinase (p38 MAP kinase) in cockroach-stimulated eosinophils. RESULTS: German cockroach extract induced degranulation and superoxide production from human eosinophils. In addition, incubation of eosinophils for 3 h with the cockroach extract resulted in an increased level of the surface expression of CD11b and CD69. Furthermore, cockroach-induced superoxide production from eosinophils was significantly inhibited by the pretreatment of cells with a p38 MAP kinase inhibitor SB202190. Indeed, a large amount of phosphorylated forms of p38 MAP kinase was detected in cockroach-stimulated eosinophils. CONCLUSIONS: Our results suggest that German cockroach extract induces activation of human eosinophils to release cytotoxic inflammatory mediators such as superoxide and granular proteins.

Allergens↗
PubMed1988

Effect of chemotactic agents on rat and guinea pig eosinophil cytotoxicity in vitro.

Purified guinea pig and rat peritoneal eosinophils were examined for their ability to mediate an antibody-dependent cell cytotoxic reaction against 51Cr-labelled chick red blood cells in the presence of N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP), leukotriene B4, eosinophil chemotactic factor of anaphylaxis, or histamine. Guinea pig eosinophils were induced either by repeated intraperitoneal injections of polymyxin B sulphate or by a single intraperitoneal injection of saline. Using subagglutinating concentrations of antibody, the antibody-dependent cell cytotoxic response was significantly enhanced with FMLP, leukotriene B4, and eosinophil chemotactic factor of anaphylaxis. Histamine was without effect. Rat eosinophils were induced either by three intravenous injections of Sephadex G-200 followed by saline intraperitoneally, by a single intraperitoneal injection of saline, or by infection with the parasite Mesocestoides corti. None of the materials examined was able to enhance the cytotoxic activity of the rat eosinophil preparations over the range tested, in the presence of subagglutinating concentrations of antibody. The antibody-dependent cell cytotoxic response of eosinophils from infected animals was significantly reduced compared with those from Sephadex/saline-treated rats. Incubation of eosinophils obtained from infected animals with FMLP in the presence of agglutinating concentrations of antibody restored eosinophil cytotoxicity. None of the other materials was active. It is concluded that the ability of rat and guinea pig eosinophils to be activated in vitro is partly species related and partly due to the method of cell induction. Differences between the two species may be important when establishing animal models of eosinophil function.

Animals↗