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A microtiter assay for activation of eosinophils. Simultaneous monitoring of eosinophil adhesion and degranulation.

A simple microtiter assay for eosinophil activation is described. The assay used 1000-4000 eosinophils/microtiter well, and the design allows for a separate or simultaneous quantitative assessment of eosinophil adhesion to protein-coated microtiter wells and degranulation after stimulation with eosinophil-activating factors. The number of adherent eosinophils is quantified indirectly by expressing the amount of eosinophil cationic protein (ECP) extracted from the adherent fraction of cells in percentage of the total amount of ECP extracted from the cells added to the wells. Degranulation is quantified in the same way by expressing the amount of ECP or eosinophil protein X (EPX) released to the supernatant in percentage of the total amount of ECP or EPX. Known eosinophil-activating agents such as PMA, interleukin (IL)-3, IL-5, GM-CSF, and platelet-activating factor (PAF) all induced a time- and dose-dependent adhesion to albumin-coated wells, whereas L-PAF did not. Kinetic experiments showed that most adhesion occurred within the first 15-30 min, reaching a plateau around 60 min. After prolonged incubation, a decline in adhesion was detected. GM-CSF-induced adhesion was completely inhibited by incubation with monoclonal antibodies directed against the common beta 2-chain (CD18) of the LFA-1, Mac-1, p150,95 complexes. Monoclonal antibodies against CD11a, CD11b, CD11c, VLA-4 ALFA, ICAM-1, VCAM-1, Sialyl-Le(x), ELAM-1, and LECAM had no inhibitory effect. Simultaneous monitoring of adhesion and degranulation after stimulation of eosinophils in albumin-coated wells with either PMA or GM-CSF showed that adhesion always preceded degranulation. Replacing the albumin coating of the microtiter wells with IgG or secretory IgA augmented both the spontaneous and the PMA- or GM-CSF-stimulated responses. In conclusion, the assay allows dynamic evaluation of eosinophil activation and can be used to assess soluble eosinophil-activating factors as well as to study eosinophil activation by solid-phase-bound proteins.

Antibodies, Monoclonal↗

Degranulation patterns of eosinophil granulocytes as determinants of eosinophil driven disease.

BACKGROUND: Degranulation of eosinophils in target tissues is considered a key pathogenic event in major chronic eosinophilic diseases. However, because of a lack of appropriate methods, little is known about degranulation of eosinophils in common eosinophilic diseases. METHODS: Using transmission electron microscopic (TEM) analysis, a novel approach has been devised and validated to quantify eosinophil degranulation in human tissues (assessed in individual cells as percentage granules with structural signs of protein release). Biopsy specimens from patients with inflammatory bowel disease, allergic rhinitis, asthma, and nasal polyposis were evaluated. RESULTS: All conditions displayed a similar degree of local tissue eosinophilia, with no differences being observed in eosinophil numbers in the airway mucosa of patients with airway diseases and the colonic mucosa of those with inflammatory bowel disease (IBD). In contrast, marked differences in the mean (SE) extent of eosinophil degranulation were observed between the patient groups; IBD 9.3 (1.4)% altered granules, artificial and natural allergen challenge induced allergic rhinitis 67.8 (6.8)% and 86.6 (3.0)%, respectively, asthma 18.1 (2)%, and nasal polyposis 46.6 (7.6)%. CONCLUSIONS: This study provides the first quantitative data which show that different eosinophilic conditions, despite having similar numbers of tissue eosinophils, may exhibit markedly different degranulation patterns. The present assessment of piecemeal degranulation would thus make it possible to delineate the conditions under which eosinophils are likely to contribute to disease processes. This novel type of analysis may also guide and validate anti-eosinophilic treatment options.

Apoptosis↗

Predominant implication of IL-5 in acute eosinophilic pneumonia: comparison with chronic eosinophilic pneumonia.

BACKGROUND: Acute eosinophilic pneumonia (AEP) is a rare disease with unknown etiology. To examine pathophysiology of AEP we measured the cell number of eosinophils and eosinophil active cytokines in the peripheral blood and bronchoalveolar lavage fluid (BALF) of AEP patients and compared the levels with those measured in chronic eosinophilic pneumonia (CEP) patients. METHODS: Cell number of eosinophils in peripheral blood and BALF from patients with AEP (n = 3) and CEP (n = 3) were measured. Eosinophil active cytokines in serum and BALF from the patients were measured using ELISA. RESULTS: Eosinophil cell number in peripheral blood was 274-1,377/mm3 in AEP and 526-2,500/mm3 in CEP. The percentages of BALF eosinophils were high in AEP and CEP. Eosinophilia disappeared after methylprednisolone pulse therapy (1 g for 3 days) in AEP, however the cell number of eosinophils gradually increased after methylprednisolone pulse therapy and then spontaneously decreased to within normal range without any further medication. The concentrations of IL-5 in AEP were very high in serum and in BALF, however the concentrations in CEP were low in serum and BALF. CONCLUSION: AEP is a disease in which eosinophil active cytokine IL-5 is predominantly involved; CEP is not. The factors involving eosinophil infiltration to inflammatory loci differ between AEP and CEP.

Acute Disease↗

LFA-1 expression by blood eosinophils is increased in atopic asthmatic children and is involved in eosinophil locomotion.

Allergic asthma is characterized by eosinophil migration in the airways, which is strictly dependent on the expression of adhesion molecules. This study investigated whether the expression of adhesion molecules on eosinophils is increased and associated with disease activity in allergic asthma. Twenty atopic asthmatic (AA) subjects and nine controls were studied and the expression of lymphocyte function-associated antigen-1 (LFA-1; CD11a/CD18), Mac-1 (CD11b/CD18) and very late antigen-4 (VLA-4; CD49d/CD29) on blood eosinophils was evaluated by specific monoclonal antibody (Mab) staining and flow-cytometric analysis. Compared with controls, eosinophils from AA showed increased expression of LFA-1 (p<0.005), but not of Mac-1 or VLA-4 (p>0.1). In addition, LFA-1 expression correlated positively with blood eosinophil number (r=0.792, p<0.05), while no correlations were observed between Mac-1 or VLA-4 expression and blood eosinophil number. The migration of eosinophils through human umbilical vein endothelial cells with or without anti-LFA-1, Mac-1 and VLA-4-blocking Mab was studied. Compared with controls, eosinophils from AA showed increased migration toward C5a (p<0.01). Cell migration was totally inhibited by preincubating eosinophils with anti-LFA-1 (p<0.05), while anti-Mac-1 had no effect (p>0.1). Thus, the expression of lymphocyte function-associated antigen-1 by blood eosinophils is increased in atopic asthmatics and seems to modulate the enhanced eosinophil migration observed in allergic asthma.

Asthma↗

Inhibition of eosinophilic inflammation in allergen-challenged, IL-1 receptor type 1-deficient mice is associated with reduced eosinophil rolling and adhesion on vascular endothelium.

To determine the relative in vivo importance of IL-1 release after allergen challenge to the subsequent endothelial adhesion and recruitment of eosinophils, the authors used ovalbumin sensitization and inhalation challenge to induce airway eosinophilia in IL-1 receptor type 1-deficient and control wild-type mice. Bronchoalveolar lavage (BAL) eosinophil recruitment in IL-1 receptor type 1-deficient mice challenged with ovalbumin (24.3% +/- 6.3% BAL eosinophils) was significantly reduced compared with wild-type mice (63.7% +/- 2.5% BAL eosinophils). To determine whether the inhibition of eosinophil adhesion to vascular endothelium contributed to the inhibition of eosinophil recruitment in IL-1 receptor type 1-deficient mice, the authors used intravital microscopy to visualize the rolling and firm adhesion of fluorescence-labeled mouse eosinophils in the microvasculature of the allergen-challenged mouse mesentery. Eosinophil rolling, eosinophil firm adhesion to endothelium, and transmigration across endothelium (peritoneal eosinophils) were significantly inhibited in allergen-challenged IL-1 receptor type 1-deficient mice compared with wild-type mice. Overall, these studies demonstrate that cytokines such as IL-1, released after allergen challenge, are important in the induction of endothelial cell adhesiveness, a prerequisite for the recruitment of circulating eosinophils. (Blood. 2000;95:263-269)

Allergens↗

Pivotal role of 5-lipoxygenase in the activation of human eosinophils: platelet-activating factor and interleukin-5 induce CD69 on eosinophils through the 5-lipoxygenase pathway.

CD69 is an activation-related cell surface molecule on human eosinophils. It has been reported that interleukin (IL)-5, but not platelet-activating factor (PAF), can induce CD69 on human eosinophils in vitro. In this study, PAF induced CD69 intensely on eosinophils from patients with hypereosinophilic syndrome (HES), while only weakly on those from normal donors. Because HES eosinophils contain abundant cytosolic phospholipase A2 (cPLA2) and 5-lipoxygenase (5-LO), we examined the roles of several enzymes involved in the metabolism of arachidonic acid in the PAF- or IL-5-induced CD69 expression on eosinophils. The CD69 expression induced by PAF and IL-5 on HES eosinophils and that by IL-5 on normal eosinophils were both inhibited by AA861 and MK-886, inhibitors of 5-LO activity. In addition, AACOCF3, a selective cPLA2 inhibitor, inhibited IL-5-induced CD69 expression on normal eosinophils, although it hardly affected either IL-5- or PAF-induced CD69 expression on HES eosinophils. Moreover, PAF alone induced CD69 only weakly on normal eosinophils, but exogenous arachidonic acid remarkably enhanced PAF-induced CD69 expression on them. These findings suggest that IL-5 activates both cPLA2 and 5-LO but PAF activates only 5-LO. It is suggested that 5-LO plays a critical role in the induction of CD69 on eosinophils.

Antigens, CD↗

[Characterization of a receptor for interleukin-5 on pulmonary eosinophils with eosinophilic pneumonia].

Interleukin-5 (IL-5) acts on eosinophil differentiation and activation, suggesting the existence of a membrane receptor for IL-5 on eosinophils. Here, we report that 125I-labeled recombinant human IL-5 bound to high affinity receptors on human eosinophils, especially pulmonary eosinophils in eosinophilic pneumonia obtained bronchoalveolar lavage (BAL). No specific binding occurred on neutrophils, nor on the undifferentiated eosinophilic cell line. EoL-3, in the absence of stimulation. The specific binding of IL-5 was induced by incubation at 37 degrees C of human eosinophils and EoL-3 cells with GM-CSF and with the supernatants of BAL cells from patients with eosinophilic pneumonia. These results indicate the existence of a specific binding site for IL-5 on human eosinophils with variable affinity in eosinophil hypodense or normodense subpopulations, as previously reported for other membrane receptors. Furthermore, lung cells (BAL cells) in patients with eosinophilic pneumonia may be involved in the production certain eosinophilopoietic growth cytokines such as IL-3, GM-CSF and IL-5.

Binding Sites↗

Eosinophil transendothelial migration induced by cytokines. I. Role of endothelial and eosinophil adhesion molecules in IL-1 beta-induced transendothelial migration.

IL-1 beta promotes adhesiveness in human umbilical vein endothelial cells (HuVEC) for eosinophils through expression of adhesion molecules including intercellular adhesion molecules-1 (ICAM-1), E-selectin, and vascular cell adhesion molecule-1 (VCAM-1). Using an in vitro endothelial monolayer system, we examined whether IL-1 beta or TNF-alpha can promote eosinophil transendothelial migration. We also evaluated the contributions of ICAM-1, E-selectin, VCAM-1, leukocyte adhesion complex (CD11/18), and very late Ag-4 (CD11b/18) (VLA-4) in this process using blocking mAb, and determined the changes in expression of CD11b and L-selectin on eosinophils that had undergone transmigration. IL-1 beta and TNF-alpha treatment of HuVEC (4 h, 5 ng/ml) induced significant transendothelial migration of eosinophils (a 4.1 +/- 0.4-fold (IL-1 beta) and 2.0 +/- 0.9-fold (TNF-alpha) increase from the spontaneous value of 3.2 +/- 0.3%). Increased CD11b expression and shedding of L-selectin were observed on eosinophils following IL-1 beta-induced eosinophil transendothelial migration. Studies with mAb revealed that blockade of either ICAM-1 or CD11/18 inhibited transmigration, while antibodies against VCAM-1 and VLA-4 had no inhibitory effect. Among antibodies which block beta 2 integrins, anti-CD18 mAb had the best inhibitory effect (88% inhibition). The combined inhibitory effect of anti-CD11a mAb and anti-CD11b mAb was roughly equal to that of anti-CD18, although anti-CD11a (31% inhibition) and anti-CD11b (52% inhibition) were less effective individually. Anti-ICAM-1 by itself inhibited IL-1 beta-induced eosinophil transendothelial migration (24% inhibition) whereas neither anti-E-selectin nor anti-VCAM-1 were effective inhibitors. Interestingly, the combination of anti-E-selectin and anti-VCAM-1 with anti-ICAM-1 inhibited IL-1 beta-induced eosinophil transendothelial migration significantly better (53% inhibition) than anti-ICAM-1 alone. These results suggest that although the initial attachment of eosinophils to IL-1 beta-activated endothelial cells involves VCAM-1, E-selectin, and ICAM-1, the subsequent transendothelial migration process relies heavily on ICAM-1 and CD11/18. Finally, the changes that eosinophils have been observed to undergo during infiltration in vivo, namely increased expression of CD11/18 and shedding of L-selectin, appear to take place as a direct result of the interaction between eosinophils and endothelial cells.

Antibodies, Monoclonal↗

Identification of a novel and highly potent eosinophil chemotactic lipid in human eosinophils treated with arachidonic acid.

Purified human eosinophils generate eosinophil chemotactic lipids (ECL), when incubated with arachidonic acid without any stimulus. Reversed phase HPLC of incubation supernatants revealed major lipid-like eosinophil chemotactic activity eluting in a peak containing 5(S), 15(S)dihydroxy-6,13-trans-8,11-cis-eicosatetraenoic acid (5,15-DiHETE) as well as a 8,15-dihydroxyeicosatetraenoic acid. For further characterization of the ECL, some authentic dihydroxyeicosatetraenoic acids were tested for eosinophil chemotactic activity. Only 5,15-DiHETE as well as 8(S), 15(S)-dihydroxy-5,11-cis-9,13-trans-eicosatetraenoic acid were found to be chemotaxins for human eosinophils, however, with an ED50 near 0.3 microM and 1.5 microM, respectively. The presence of high titer eosinophil chemotactic activity in ECL preparations let us look for a contaminating ECL with higher specific activity. By using a different reversed phase HPLC-system 5,15-DiHETE as well as 8(R), 15(S)-dihydroxy-5,11-cis-9,13-trans-eicosatetraenoic acid could be separated from a highly potent ECL. Final purification of this ECL by the use of straight phase HPLC resulted in a single at 260 nm absorbing peak giving an UV spectrum different from that known for eosinophil chemotactic factors indicating a novel type of eosinophil chemotactic lipid. Eosinophil chemotactic activity of purified ECL has been found to be similar to that seen for platelet-activating factor, the most potent chemotaxin so far known, either in the number of migrating cells or the ED50. Cross-desensitization experiments with ECL, leukotriene B4, and platelet-activating factor revealed the existence of a separate ECL receptor on eosinophils. The production of potent ECL by the responder cells themselves supports the idea that there exists a self-sustaining mechanism of eosinophil accumulation.

Arachidonate 15-Lipoxygenase↗

Eosinophilic lung disease: immunological studies of blood and alveolar eosinophils.

Five patients with eosinophilic lung diseases and blood hypereosinophilia (PIE syndrome) were investigated clinically and by bronchoalveolar lavage (BAL). Comparative studies on blood and alveolar eosinophils were carried out after purification and selection of eosinophil subpopulations according to their density. A predominant 'hypodense' alveolar eosinophil population was found in BAL fluids of active chronic eosinophilic pneumonia (CEP). In addition, supernatants of alveolar macrophages obtained from CEP are able to enhance spontaneously the generation of eosinophil oxygen metabolites. Such eosinophil stimulation emphasizes a probable tissue cell cooperation. In addition, BAL permitted the study of membrane immunological markers on eosinophilic inflammatory cells endowed with migratory properties. An increase in eosinophils carrying surface IgE was demonstrated in alveolar cells from PIE Syndrome particularly with hypodense eosinophils from CEP patients. Although no specific stimulus is known at the present time, this work underlines the potential implication of IgE-mediated hypersensitivity processes in the pathogenesis of eosinophilic lung diseases.

Adult↗

Eosinophilic fasciitis and eosinophilic cellulitis in a patient with abnormal circulating clonal T cells: increased production of interleukin 5 and inhibition by interferon alfa.

Eosinophilic fasciitis (Shulman's syndrome) and eosinophilic cellulitis are part of a spectrum of diseases characterized by tissue and peripheral blood eosinophilia. Eosinophils are implicated directly in the lesional process that characterizes these conditions, because signs of eosinophil activation and degranulation are observed at the sites of tissue injury. The cause and pathogenesis of eosinophilic fasciitis and cellulitis are presently unclear. Herein, we report a patient manifesting rapidly progressive localized cutaneous induration of the arms and legs with eosinophilia, no signs of systemic sclerosis, and histopathologic features compatible with the diagnosis of eosinophilic fasciitis. Four years after the onset of eosinophilic fasciitis, the patient had recurrent episodes of eosinophilic cellulitis. Blood screening for clonal T-cell receptor gamma gene rearrangements revealed several amplified clonal populations of circulating T cells. Furthermore, in vitro analysis of cytokine production by the patient's peripheral blood mononuclear cells demonstrated strongly increased production of interleukin 5, the synthesis of which could be completely blocked by interferon (IFN)-alpha. The coexistence of eosinophilic fasciitis and cellulitis in a patient with an abnormal circulating T-cell clone and increased IL-5 production are unique and might be responsible for the eosinophilia and eosinophil-mediated tissue injury. Although not assessed in vivo in this patient, our in vitro data provide a rationale for the use of IFN-alpha in eosinophilic fasciitis and/or cellulitis.

Aged↗

Cytokine production from sputum cells in eosinophilic versus non-eosinophilic asthmatics.

The inflammatory pathways involved in asthma are more complex than the sole Th2-mediated eosinophilic airway inflammation. Different phenotypes of asthma have been recently highlighted and are probably underlied by different immunological profiles. The aim of the study was to assess cytokine production from sputum cells in eosinophilic versus non-eosinophilic asthmatics. Induced sputum was obtained from 48 consecutive stable mild to moderate asthmatics (20 eosinophilic asthmatics, 28 non-eosinophilic asthmatics) and 31 healthy subjects. Cytokine released from sputum cells were measured by a home-made two-step sandwich immunoassay. Cytokines investigated were interleukin (IL)-4, IL-6, IL-10, tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma. Sputum cells from eosinophilic asthmatics produced more IL-4 than those from both healthy subjects (P < 0.05) and non-eosinophilic asthmatics (P < 0.05). Conversely, sputum cells from eosinophilic asthma were found to release lower amounts of TNF-alpha than those from healthy subjects (P < 0.05). The group of non-eosinophilic asthmatics did not distinguish from healthy subjects with respect to any cytokines measured. Sputum cells from asthmatics exhibiting eosinophilic airway inflammation release more IL-4 and less TNF-alpha than those of healthy subjects. By contrast, non-eosinophilic asthmatics did not distinguish from healthy subjects by abnormal cytokine release from their sputum cells.

Adult↗

Eosinophils and eosinophilic cationic protein in induced sputum and blood: effects of budesonide and terbutaline treatment.

BACKGROUND: There is a need for easily measurable markers of airway inflammation to guide the use of anti-inflammatory treatment in asthma. Eosinophilic cationic protein (ECP) levels in sputum and blood correlate with clinical severity, and serial measurements of ECP have been proposed as a suitable candidate. AIMS AND METHODS: Our aim was to confirm that sputum and serum ECP measurements would provide a more sensitive indicator of responses to asthma treatment than eosinophil counts per se, in a randomized, placebo-controlled, crossover study of terbutaline, budesonide, and their combination in patients with chronic persistent asthma. We compared the changes in eosinophil counts and ECP in induced sputum and blood during each treatment period. RESULTS: Budesonide and combined treatment caused a significant reduction in sputum eosinophils (-2.7% and -2.3%, respectively, P < 0.05). Sputum eosinophils increased with terbutaline (+3.9%, P = 0.049). In contrast, the changes for sputum ECP were not significant. There was a similar treatment effect on blood eosinophils, but not for serum ECP. Correlations between sputum and blood eosinophils were significant with and without budesonide, but were nonsignificant between sputum and blood ECP during the active treatments. Correlations between sputum eosinophils and ECP, and between blood eosinophils and serum ECP were greatest during treatment with placebo or terbutaline alone: budesonide weakened or abolished these relationships. CONCLUSIONS: Compared with eosinophil counts, ECP measurements in either induced sputum or serum failed to reflect treatment-related changes in chronic asthma. We conclude that ECP is not a sensitive or reliable means of evaluating airway inflammation, and can not be recommended for assessing responses to anti-inflammatory therapy.

Administration, Topical↗

Kimura's disease with unusual eosinophilic epithelioid granulomatous reaction: a finding possibly related to eosinophil apoptosis.

We report and discuss a case of Kimura's disease with an unusual eosinophilic epithelioid granulomatous reaction. A 3-year-old Japanese boy with eosinophilia and a high concentration of IgE developed lymphadenopathy and multiple cervical masses. A lymph node biopsy demonstrated the infiltration of eosinophils in the stroma, which is consistent with the findings of Kimura's disease. Interestingly, a number of apoptotic eosinophils was detected in the infiltrating eosinophils. Multiple epithelioid granulomas with central eosinophilic abscesses and necrosis were also observed. Macrophages and giant cells had phagocytosed the apoptotic eosinophils at the edge of the granulomas. In situ terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) assay showed that the TUNEL-positive eosinophils were both in the macrophages and in the central eosinophilic abscesses of the granulomas. These findings suggest that the eosinophils had undergone an accelerated apoptosis in this case of Kimura's disease, and that the epithelioid granulomas were produced by phagocytosis of the apoptotic eosinophils by macrophages.

Angiolymphoid Hyperplasia with Eosinophilia↗

Differences in responses of rat- and guinea-pig-eosinophils to eosinophil chemotactic factors derived from Angiostrongylus cantonensis.

Eosinophil chemotactic activity associated with whole worm extracts of the young adult worms (YA) and 1st stage larvae (L1) of Angiostrongylus cantonensis was assessed using guinea-pig- and rat-eosinophils. Both whole worm extracts were potently chemotactic to guinea-pig-eosinophils whereas only the whole worm extract of L1 was chemotactic to rat-eosinophils. Gel filtration chromatography of YA-whole worm extract yielded an eosinophil chemotactic factor (ECF-YA) with an estimated molecular weight of 16,900. ECF-YA was resistant to heating and pronase digestion but sensitive to periodate oxidation, suggesting that chemotactic activity was possibly associated with the sugar portion of the glycoprotein molecule. Guinea-pig- and rat-eosinophils were deactivated by previous incubation with homologous whole worm extracts but not with heterologous ones. When guinea-pig-eosinophils were treated with trypsin or pronase, their chemotaxis to ECF-YA was significantly inhibited, and pronase treatment was more effective. Both deactivated and trypsin-treated guinea-pig-eosinophils completely recovered their chemotaxis responses after in vitro culture for 12 and 24 h, respectively. When those eosinophils were cultured in vitro in the presence of puromycin or cycloheximide, however, their chemotaxis responses could not be recovered. These data clearly indicate that guinea-pig-eosinophils probably possess a kind of receptor (or 'recognition unit') capable of reacting to ECF-YA, and also that the receptor may be protein or glycoprotein molecules, and reproducible.

Angiostrongylus↗

Peripheral blood eosinophil counts and eosinophil cationic protein content of respiratory secretions in bronchiolitis: relationship to severity of disease.

Infants and young children with acute viral respiratory illness were studied to determine the association of peripheral blood eosinophil counts and concentrations of eosinophil cationic protein (ECP) in nasopharyngeal secretions with the development and severity of bronchiolitis. Subjects included those with upper respiratory illness (URI) alone, pneumonia or bronchiolitis. Controls consisted of healthy infants, and those hospitalized with non-respiratory illnesses. While peripheral blood eosinophil counts were suppressed in all infected infants greater than two months of age, eosinophil counts in patients with bronchiolitis were significantly greater than in those with URI alone. ECP concentrations were significantly greater among individuals with bronchiolitis than other infected infants. For bronchiolitis cases with detectable peripheral blood eosinophils, eosinophil counts correlated weakly and inversely with oxygen saturations. In contrast, ECP concentrations were strongly inversely correlated with initial oxygen saturation. ECP concentrations were also significantly correlated with peripheral blood eosinophil counts. Viral infections suppress peripheral blood eosinophil counts in infants greater than two months of age, although the effect is somewhat overcome in patients with bronchiolitis. The form and severity of bronchiolitis is much more strongly related to degranulation of eosinophils in the respiratory tract than to peripheral blood eosinophil counts.

Blood Proteins↗

Elevated circulating levels of eosinophil cationic protein in uremia as signs of abnormal eosinophil homeostasis.

Circulating levels of eosinophil cationic protein (ECP), an eosinophil-specific granule protein, and peripheral eosinophils were determined in 56 patients with uremia. The patients were on a chronic hemodialysis or CAPD program or treated with diet only. They had normal counts of peripheral eosinophils but on average a threefold increase of the serum ECP concentrations compared with healthy subjects. The intracellular content of ECP in eosinophils isolated from 6 patients on maintenance hemodialysis was normal. The management or duration of the uremic condition did not influence the circulating ECP levels or eosinophil counts. Neither was any relation found between total IgE levels and peripheral eosinophils or serum ECP. The present results are compatible with an accelerated turnover of peripheral eosinophils in uremia. Such a proposed abnormal eosinophil homeostasis should demand an accelerated marrow eosinophil production, thereby explaining the previously reported marrow eosinophilia in azotemic patients.

Adult↗

Activated eosinophil infiltration and deposits of eosinophil cationic protein in renal allograft rejection.

Eosinophil involvement in renal allograft rejection was elucidated with immunocytochemical techniques. Sections of renal biopsies were stained for immunoreactive eosinophils and extracellular deposits of eosinophil cationic protein (ECP). Activated eosinophils were identified by means of alkaline-phosphatase-linked monoclonal antibodies. In biopsies from patients with acute rejection of the interstitial type, a varying degree of eosinophil infiltration in the interstitium was seen. Minor extracellular deposits of ECP were present in areas with activated eosinophils. In acute vascular rejection, dense infiltration of activated eosinophils and secreted ECP were found in infarcted areas and in arterial walls with necrotic lesions. Dense accumulation of activated eosinophils and extracellular deposits of ECP were also seen in biopsies from non-transplanted patients with necrotizing renal vasculitides. These findings suggest that cytotoxic eosinophil granule proteins are involved in vascular injury in renal graft rejection and in necrotizing renal vasculitides. Eosinophil activation may also have a pathophysiological role in the interstitial lesions in renal graft rejection.

Antibodies, Monoclonal↗