Measurement of eosinophil cationic protein (ECP) and eosinophil protein X/eosinophil derived neurotoxin (EPX/EDN). Time and temperature dependent spontaneous release in vitro demands standardized sample processing

Clinical Potential of Eosinophil-Derived Neurotoxin in Asthma Management

The assessment and management of patients with asthma is challenging because of the complexity of the underlying inflammatory mechanisms and heterogeneity of their clinical presentation. Optimizing disease management requires therapy individualization that should rely on reliable biomarkers to unravel the phenotypes and endotypes of asthma. The secretory activity and turnover of eosinophils, as assessed by measuring eosinophil-derived proteins, may provide an accurate and complementary tool that mirrors the eosinophil activation status. Emerging evidence suggests that eosinophil-derived neurotoxin has considerable potential as a precision medicine biomarker. In this review, we explore the suitability of eosinophil-derived neurotoxin as a biomarker in asthma management, with particular emphasis on its clinical significance in the management of both pediatric and adult populations.

Blood eosinophil cationic protein and eosinophil-derived neurotoxin are associated with different asthma expression and evolution in adults

BACKGROUND

Eosinophil-derived neurotoxin (EDN) and eosinophil cationic protein (ECP) are proteins released by activated eosinophils whose role in adult asthma remains unclear.

OBJECTIVE

To study associations between ECP, EDN and various asthma characteristics in adults from the Epidemiological Study on the Genetics and Environment of Asthma (EGEA).

METHODS

Plasma ECP and EDN levels were measured by ELISA. Cross-sectional analyses were performed in 941 adults (43±16 years old, 39% with asthma) at EGEA2 (2003-2007). Longitudinal analyses investigated the associations between EDN level at EGEA2 and changes in asthma characteristics between EGEA2 and EGEA3 (2011-2013, n=817). We used generalised estimated equations adjusted for age, sex, smoking status and body mass index to take into account familial dependence.

RESULTS

At EGEA2, both high ECP and EDN levels were associated with current asthma (adjusted OR (aOR) (95% CI): 1.69 (1.35-2.12) and 2.12 (1.76-2.57)). Among asthmatics, high EDN level was associated with asthma attacks (aOR: 1.50 (1.13-1.99)), wheezing and breathlessness (aOR: 1.38 (1.05-1.80)), use of asthma treatments (aOR: 1.91 (1.37-2.68)) and bronchial hyper-responsiveness (aOR: 2.03 (1.38-2.97)), even after further adjustment on ECP. High ECP level was associated with high neutrophil count and tended to be associated with chronic bronchitis. High EDN level at EGEA2 was associated with persistent asthma (aOR: 1.62 (1.04-2.52)), nocturnal symptoms (aOR from 2.19 to 3.57), worsening wheezing and breathlessness (aOR: 1.97 (1.36-2.85)) and nocturnal shortness of breath (aOR: 1.44 (1.04-1.98)) between EGEA2 and EGEA3.

CONCLUSIONS

EDN and ECP were associated with different asthma expression in adults. EDN could be a potential biomarker to monitor asthma evolution in adults.

CCL11 elicits secretion of RNases from mouse eosinophils and their cell-free granules

Rapid secretion of eosinophil-associated RNases (EARs), such as the human eosinophilic cationic protein (ECP), from intracellular granules is central to the role of eosinophils in allergic diseases and host immunity. Our knowledge regarding allergic inflammation has advanced based on mouse experimental models. However, unlike human eosinophils, capacities of mouse eosinophils to secrete granule proteins have been controversial. To study mechanisms of mouse eosinophil secretion and EAR release, we combined an RNase assay of mouse EARs with ultrastructural studies. In vitro, mouse eosinophils stimulated with the chemokine eotaxin-1 (CCL11) secreted enzymatically active EARs (EC(50) 5 nM) by piecemeal degranulation. In vivo, in a mouse model of allergic airway inflammation, increased airway eosinophil infiltration (24-fold) correlated with secretion of active RNases (3-fold). Moreover, we found that eosinophilic inflammation in mice can involve eosinophil cytolysis and release of cell-free granules. Cell-free mouse eosinophil granules expressed functional CCR3 receptors and secreted their granule proteins, including EAR and eosinophil peroxidase in response to CCL11. Collectively, these data demonstrate chemokine-dependent secretion of EARs from both intact mouse eosinophils and their cell-free granules, findings pertinent to understanding the pathogenesis of eosinophil-associated diseases, in which EARs are key factors.

Major basic protein homolog (MBP2): a specific human eosinophil marker

Human eosinophil granule major basic protein (MBP1) is an exceedingly basic (isoelectric point >11) 14-kDa protein, comprising the core of the secondary eosinophil granule. Recently, a less cationic homolog of MBP, termed MBPH or simply, MBP2, has been discovered. We prepared a panel of mAbs to MBP2 and used these Abs to localize and quantitate this molecule in leukocytes and biological fluids. Specific mAbs for MBP2 were selected using slot-blot analyses and used in a two-site immunoassay, Western blotting, and immunofluorescence microscopy. The sensitivity of the immunoassay was markedly improved by reduction and alkylation of MBP2. MBP1 is more abundant than MBP2 in lysates of eosinophils and their granules, as judged by immunoassay and Western blotting. By immunofluorescence, MBP1 is present in eosinophils, basophils, and a human mast cell line (HMC1), whereas MBP2 is only detected in eosinophils. Neither MBP1 nor MBP2 could be detected in any other peripheral blood leukocyte. MBP2 levels measured in plasma and serum were essentially identical. In contrast to past measurements for MBP1, MBP2 was not detected above normal levels in sera from pregnant donors. However, measurement of serum MBP2 discriminated patients with elevated eosinophils from normal subjects, and MBP2 was also detectable in other biological specimens, such as bronchoalveolar lavage, sputum, and stool. These results indicate that MBP2 is present only in eosinophils and that it may be a useful biomarker for eosinophil-associated diseases.

Eosinophil activity in Schistosoma mansoni infections in vivo and in vitro in relation to plasma cytokine profile pre- and posttreatment with praziquantel

Eosinophil activity in vivo and in vitro was studied in relation to infection intensities and plasma cytokine profiles of 51 Schistosoma mansoni-infected Ugandan fishermen before treatment and 24 h and 3 weeks posttreatment. Blood eosinophil numbers significantly declined 24 h posttreatment, but significant eosinophilia had developed by 3 weeks posttreatment. Cellular eosinophil cationic protein (ECP) content increased significantly during the transient eosinopenia but was significantly reduced 3 weeks later. No similar reduction in cellular eosinophil protein X (EPX) content was seen. Before treatment, S. mansoni infection intensity was positively correlated with 24-h boosts in plasma interleukin-5 (IL-5) and IL-6 levels, which were in turn negatively correlated with the posttreatment fall in eosinophil numbers. Significant correlations were observed between pretreatment infection intensities and plasma IL-10 and eotaxin levels. Treatment induced significant fluctuations in plasma IL-5, IL-6, IL-10, tumor necrosis factor alpha (TNF-alpha), and eotaxin levels. Optimal relative release of ECP and EPX in vitro was detected in S. mansoni soluble egg antigen-stimulated cultures during transient eosinopenia. Our data suggest that blood eosinophils are activated during S. mansoni infection and that treatment induces a burst in released antigens, causing increased production of IL-5, IL-6, IL-10, and eotaxin; a drop in TNF-alpha levels; and a transient sequestration of eosinophils, which leaves fewer degranulated eosinophils in the circulation 24 h posttreatment, followed by the development of eosinophilia 3 weeks later. During these events, it appears that preferential release of ECP occurs in vivo. Moreover, it is possible that infection intensity-dependent levels of plasma IL-10 may be involved in the prevention of treatment-induced anaphylactic reactions.

[Activated eosinophils: techniques to characterize them]

The deleterious role thought to be played by eosinophils in many situations is linked to their ability to secrete various inflammatory substances, mainly toxic proteins and lipid mediators, in body tissue. This ability is a particular feature of activated eosinophils, which have undergone numerous metabolic, functional, and phenotypic changes from their resting state. Characterizing the properties of these activated cells is an essential step in improving our understanding of their contributions to local inflammatory response, as both regulatory and effector cells. Improvements in existing methods as well as the development of new technical approaches have facilitated the ex vivo and in vitro study of activated eosinophils and their contribution to various disease states.

Circulating eosinophils in asthma, allergic rhinitis, and atopic dermatitis lack morphological signs of degranulation

BACKGROUND

In allergic diseases, eosinophils in affected tissues release granule proteins with cytotoxic, immunoregulatory, and remodelling-promoting properties. From recent observations, it may be assumed that eosinophils degranulate already in circulating blood. If degranulation occurs in the circulation, this could contribute to widespread systemic effects and provide an important marker of disease.

OBJECTIVE

To determine the degranulation status of circulating eosinophils in common allergic diseases.

METHODS

Using a novel approach of whole blood fixation and leucocyte preparation, the granule morphology of blood eosinophils from healthy subjects, non-symptomatic patients, symptomatic patients with asthma, asthma and Churg-Strauss syndrome, allergic rhinitis, and atopic dermatitis was evaluated by transmission electron microscopy (TEM) and eosinophil peroxidase (TEM) histochemistry. Plasma and serum levels of eosinophil cationic protein were measured by fluoroenzymeimmunoassay. Selected tissue biopsies were examined by TEM.

RESULTS

Regardless of symptoms, circulating eosinophils from allergic patients showed the same granule morphology as cells from healthy subjects. The majority of eosinophil-specific granules had preserved intact electron-density (96%; range: 89-98%), while the remaining granules typically exhibited marginal coarsening or mild lucency of the matrix structure. Abnormalities of the crystalline granule core were rarely detected. Furthermore, granule matrix alterations were not associated with any re-localization of intracellular EPO or increase in plasma eosinophil cationic protein. By contrast, eosinophils in diseased tissues exhibited cytolysis (granule release through membrane rupture) and piecemeal degranulation (loss of granule matrix and core structures).

CONCLUSION

In symptomatic eosinophilic diseases, circulating blood eosinophils retain their granule contents until they have reached their target organ.

Monitoring the allergic inflammation

Individual symptoms of allergy such as asthma, dermatitis, rhinitis have many different underlying mechanisms. The detailed characterization of the inflammatory mechanisms underlying symptom development in the individual patient is important in order to optimally control treatment. Measurement of eosinophil cationic protein (ECP) in sputum or blood and eosinophil protein X/eosinophil derived neurotoxin (EPX/EDN) in urine may be used to read the involvement of the eosinophil granulocyte in the process. An important information as eosinophil dominated processes seem to be particularly sensitive to corticosteroid treatment. The possibilities to measure the involvement of other inflammatory cells exist today, but are only used to a small extent. The dream would be that every patient with an inflammatory disease is characterized with respect to the profile of involving cells and mediators. Such information would provide us with a unique understanding of the underlying mechanisms of the development of disease symptoms and the possibilities of treating these.

Eosinophil granule proteins in the assessment of airway inflammation in pediatric bronchial asthma

Eosinophil granule proteins such as eosinophil cationic protein (ECP), eosinophil peroxidase (EPO) and eosinophil protein X (EPX) in serum and urine are indirect measures of eosinophil activity. The measures have been evaluated for prediction, diagnosis and monitoring of anti-inflammatory treatment modalities in children with asthma. Assessments in serum and urine are highly dependent on sampling procedures and must be performed under strictly controlled conditions using standardized sampling and laboratory procedures. The measures are influenced by circadian and seasonal variations. Measurement of the eosinophil granule proteins does not improve the predictive value of a family history of atopy. Due to insufficient sensitivity and specificity, the measures are not useful in the diagnosis of asthma in children, and the clinical use of eosinophil proteins in the individual child for assessment of asthma severity has not been sufficiently validated. Serum and urine eosinophil granule proteins, however, may be useful in extending our knowledge of suppressive effects on eosinophil activity of various doses, devices and administration regimens of inhaled glucocorticoids in children. Such evaluations may be performed in randomized, double-blind trials of well-defined age groups and they should include measures of compliance. One important aspect to look at would be the distinction between suppressive effects on eosinophil activity and clinically important anti-inflammatory effects. Considering the complexity of airway inflammation and the heterogeneity of childhood asthma, however, it may be too simplistic to look for a single measure of the inflammatory processes. In the future, perhaps, a combination of products of inflammatory cells may give more clinically relevant information with respect to prediction, diagnosis, monitoring and outcome of childhood asthma.

Circadian variations in serum eosinophil cationic protein, and serum and urine eosinophil protein X

Biochemical evaluation of inflammation may be a useful adjunct to measures of pulmonary function and symptoms in children with asthma. However, little data have been provided to validate the markers in children. The aim of the present study was to assess circadian variations in serum eosinophil cationic protein (ECP), and serum and urine eosinophil protein X (EPX) in children. Five girls and two boys aged 10-14 years were studied. The first sample of urine consisted of urine collected from 24.00 hours the night before until 08.00 hours on the morning of the day of investigation. Thereafter urine was collected at 4-h intervals until 24.00 hours and in another 8-h interval from 24.00 to 08.00 hours. Blood samples for assessment of serum ECP and serum EPX were collected every 2 h during the 24 h. Statistically significant circadian variations in serum ECP (F=3.2, p=0.002), serum EPX (F=3.1, p=0.002) and in urine EPX/creatinine (F=5.4, p=0.003) were detected. The concentrations were higher during the night compared to daytime. Peak levels of serum ECP (mean [+/- SEM]) were found at 06.00 hours (16.3 [5.3] micro g/l), trough levels at 08.00 hours (3.9 [0.7] micro g/l) (p=0.01). Peak levels of serum EPX were seen at 06.00 (43.7 [9.5] micro g/l) with trough levels at 12.00 hours (22.0 [3.5] micro g/l) (p=0.01). Peak levels of urine EPX/creatinine occurred in urine collected from 24.00 to 08.00 hours (90.0 [27.7] micro g/mmol), trough levels in the 16.00-20.00 hours sample (29.7 [8.9] micro g/mmol) (p=0.02). Serum ECP, serum EPX and urine EPX exhibit a circadian variation in children with nocturnal and early morning peak levels. To avoid confounding influence from circadian variations in ECP and EPX in clinical studies blood or urine should be sampled at consistent times.

Increased serum concentration of eosinophil-derived neurotoxin in patients with Graves' disease

Eosinophil-derived neurotoxin (EDN) is released after activation and stimulation of eosinophils in allergic disease, which is a T(H)2-predominant condition. We previously reported that Graves' thyrotoxicosis develops or relapses after an attack of allergic rhinitis. In this study, to confirm the relation between Graves' disease and the allergic condition, we determined the serum level of EDN in 30 untreated patients with Graves' disease, 50 patients with Hashimoto's thyroiditis, and 39 normal controls. Compared to the serum level in normal subjects (30.1 +/- 15.6 ng/mL), EDN was increased in untreated patients with Graves' disease (52.4 +/- 27.6 ng/mL), but not in patients with Hashimoto's thyroiditis (thyrotoxic, 30.9 +/- 13.4 ng/mL; euthyroid, 30.0 +/- 11.9 ng/mL; hypothyroid, 23.4 +/- 10.2 ng/mL). A significant correlation was observed between the EDN level and the serum activity of thyrotropin (TSH) receptor antibody (r = 0.541, p < 0.0001). These data suggest that the allergic condition is closely related to Graves' disease and that a T(H)2-type immune response is crucial in the pathogenesis of Graves' disease.

Measurement of inflammatory mediators of eosinophils and lymphocytes in blood in acute asthma: serum levels of ECP influence the bronchodilator response

The aim of this study was to assess the relevance of immunoinflammatory markers on the response to short acting beta(2)-agonist in acute asthma exacerbation. Thus, we measured serum eosinophil cationic protein (ECP) levels and sIL-2R at acute exacerbation in 52 adult patients with atopic asthma, and assessed forced expiratory volume in 1 s (FEV(1)) before and after the administration of aerosolized salbutamol. After a cumulative dose of salbutamol causing a 10% improvement in FEV(1) from baseline [CD10, i.e. cumulative doses of salbutamol (800 microg) causing an improvement in FEV(1) from baseline to 10%] the patients were divided into two groups: group A with CD <10 and group B with CD >10. The bronchodilator response, as defined by a DeltaFEV(1) (percentage of predictive value of FEV(1)) of > or =10 predictive value, was shown by 40% of the patients. After 200, 400 and 800 microg of salbutamol, significant differences of FEV(1) with respect to baseline values were, respectively, p = 0.049, 0.0039 and 0.0014. In contrast, no significant difference of the means of FEV(1) between the doses of salbutamol was observed. Significant differences of DeltaFEV(1) between 200 and 400 microg (p = 0.0002) and between 200 and 800 microg (p < 0.0001) were observed, but not between 400 and 800 microg of salbutamol. There were significant correlations between baseline values of predictive FEV(1) and serum ECP levels (rho = -0.60, p < 0.0001) and sIL-2R levels (rho = -0.35, p = 0.01) respectively. Besides, a correlation between DeltaFEV(1) and serum ECP levels (rho = -0.53, p < 0.0001) was observed, whereas no correlation was found between DeltaFEV(1) and sIL-2R. By analyzing differences between the two groups (A and B) for serum ECP levels, sIL-2R and blood eosinophil count, a significant difference was found for serum ECP levels. We conclude that subjects with acute exacerbation of asthma show high serum levels of ECP and sIL-2R and, more interestingly, that the response to brochodilator was higher in patients with lower serum ECP levels.

Blood eosinophil counts for the prediction of the severity of exercise-induced bronchospasm in asthma

It has been suggested that airway eosinophilic inflammation is associated with the severity of exercise-induced bronchospasm (EIB). Blood eosinophils are known to be an indirect marker of airway inflammation in asthma. The aim of this study is to investigate that a simple and easy blood test for blood eosinphil counts may predict the severity of EIB in asthma. Seventy-seven men with perennial asthma (age range 18-23 years) were included. Lung function test, skin prick test, and blood tests for eosinophils counts and total IgE levels were performed. Methacholine bronchial provocation test and, 24 h later, free running test were carried out. EIB was defined as a 15% reduction or more in post-exercise FEV1 compared with pre-exercise FEV1 value. Atopy score was defined as a sum of mean wheal diameters to allergens. EIB was observed in 60 (78%) of 77 subjects. Asthmatics with EIB showed significantly increased percentages of eosinophils (P<0.01), log eosinophil counts (P<0.001), and atopy scores (P<0.05) and decreased log PC20 values (P < 0.05) compared with asthmatics without EIB. Asthmatics with eosinophils of > 700 microl(-1) (36.9 +/- 12.7%) had significantly greater maximal % fall in FEV1 after exercise than asthmatics with eosinophils of < 350 microl(-1) (24.7 +/- 16.6%, P <0.05). Blood eosinophil counts > 350 microl(-1) yielded the specificity of 88% and positive predictive value of 93% for the presence of EIB. When a multiple regression analysis of maximal % fall in FEV1 according to log eosinophil counts, log PC20, log IgE and atopy score was performed, only blood eosinophil counts were significant factor contributing to the maximal % fall in FEV1 after exercise. These findings not only suggest that a simple blood test for eosinophils may be useful in the prediction of the severity of EIB, but also reinforce the view that airway eosinophilic inflammation may play a major role in EIB in asthma.

Measurement of airway inflammation in asthma

Chronic airway inflammation is considered responsible for symptoms and disorders of airway function associated with asthma. This process is the target of anti-inflammatory therapy, so a number of standardized, noninvasive techniques have been developed to assess it. More recent approaches include the measurement of exhaled gases and nonvolatile substances in breath condensate. Results from studies using a wide variety of inflammatory markers have shown group differences between patients with asthma and healthy control subjects, but evidence for the diagnostic use of these markers in individual patients is scarce. Similarly, despite many studies demonstrating some correlation between markers of airway inflammation and a measure of disease control, none has yet convincingly shown a place for the use of these markers in an individual with corticosteroid-treated asthma. However, application of these markers continues to further our understanding of the disease process and provides the potential for more appropriate, customized therapy.

Urine eosinophil protein X (EPX) is an in vitro parameter of inflammation in atopic dermatitis of the adult age

BACKGROUND

Eosinophils are important effector cells in several atopic diseases. The levels of eosinophil granule-derived mediators (ECP, EPX) in serum and body fluids have been proven to be correlated with disease activity in atopic respiratory diseases and atopic dermatitis. The study aimed to demonstrate an interrelationship between urine EPX and disease activity in adult patients with atopic dermatitis.

METHODS

We determined urine EPX concentration, serum ECP concentration, and peripheral blood eosinophil count in 40 adult patients with mild to severe atopic dermatitis and compared it with the disease activity as assessed with the SCORAD index.

RESULTS

Urine EPX and serum ECP concentrations were significantly higher in patients with severe atopic dermatitis than in patients with mild or moderate disease (median values 123.5 vs 78.3 microg/mmol creatinine, P<0.0001; 25.4 vs 14.9 microg/l, P<0.0001, respectively). We found a significant correlation between urine EPX levels, serum ECP levels, and the SCORAD (r=0.36, P<0.0001 and 0.34, P<0.0001, respectively).

CONCLUSION

Urine EPX is a useful in vitro parameter of inflammation in atopic dermatitis of the adult age.

Asthma severity and inflammation markers in children

The relationship of airway inflammation with asthma severity remains unclear. Our aim was to correlate the results of recommended methods of assessment of inflammation with measures of asthma control, in children with a wide range of asthma severity. The study was a cross-sectional investigation of 58 children receiving a wide range of treatment, including 10 treated without regular maintenance therapy and 29 treated with high-dose inhaled corticosteroids (CS). Exhaled nitric oxide (NO), serum eosinophil cationic protein (ECP), and induced sputum (processed for eosinophil count and ECP level) were related to recent symptoms, lung function, and bronchial responsiveness. There was no significant correlation between the results of any

METHOD

Neither did any marker of airway inflammation relate to recent symptoms, unlike PC20, which did. There was a significant, inverse correlation between the forced expiratory volume in 1 s (FEV1) and both NO and sputum ECP (r=-0.46, p=<0.001; r=-0.48, p=0.004, respectively). Sputum eosinophils were inversely related to the dose of methacholine that corresponded to a 20% fall in FEV1 (PC20) (r=-0.57, p=0.02). Serum ECP did not relate to any measure of asthma control. There was no association of any recommended inflammation markers with current symptoms and only a weak relationship between them and physiological measures. The place of these markers remains unclear and their use in clinical practice needs further investigation by long-term longitudinal studies.

Allergen-specific immunotherapy in birch- and grass-pollen-allergic rhinitis. II. Side-effects

BACKGROUND

Allergen-specific immunotherapy (IT) involves the risk of side-effects. Different side-effect profiles have been reported for different allergens, and it would be of great benefit to be able more precisely to predict patient- and allergen-related risk factors.

METHODS

Fifty-two patients with rhinoconjunctivitis and allergy to birch as well as grass pollen participated in a 3-year IT study, with a baseline year followed by 2 years of treatment. During the first treatment year, the patients received double-blinded IT with either birch (Betula verrucosa) or grass (Phleum pratense) pollen extracts adsorbed to aluminum hydroxide. The following year, the other allergen extract was added. Assessment of systemic reactions (SRs) was performed, and related to patient pretreatment parameters such as seasonal symptoms and medication requirement, skin prick test (SPT), conjunctival provocation test (CPT), nasal provocation test (NPT), total and specific IgE, basophil histamine release (HR), eosinophil count (EOS), eosinophil cationic protein (ECP), and eosinophil protein X (EPX).

RESULTS

In total, 44 and 47 patients started IT with birch- and grass-pollen extracts, respectively. All SRs occurred during the dose-increase phase. No life-threatening SRs were observed. There were a higher number of patients with SRs during IT with grass pollen than IT with birch pollen, 21 vs five patients (P<0.001), with SRs to 3.3% of grass-pollen injections compared to 0.7% of birch-pollen injections (P<0.0001). The SRs of birch-pollen IT were mild, consisting of rhinoconjunctivitis and oral-pharyngeal itching, whereas asthma and urticaria episodes were observed in the grass-pollen IT. No difference was found in sensitivity to birch and grass, when measured by SPT, CPT, NPT, specific IgE, or HR, and no difference was found in age, duration of allergic symptoms, prevalence of asthma, mean seasonal birch/grass symptom score, eye-drop use, or antihistamine or prednisolone intake between the group with and without subsequent SRs to IT. No difference was found in EOS, serum ECP, or EPX, between the group with and without subsequent SRs to IT.

CONCLUSIONS

IT with grass-pollen extract seems to be associated with a higher number and more severe SRs than birch-pollen IT. Neither demographic data nor diagnostic tests of allergy such as specific IgE, HR, SPT, CPT, and NPT could identify the patients with subsequent SRs.

Identification of cytokine-regulated genes in human leukocytes in vivo

BACKGROUND

Human polymorphic nuclear granulocytes (PMNs) such as neutrophils and eosinophils play a critical role in mediating inflammatory responses to microbial and parasitic infections. Exposure of these leukocytes to cytokines leads to an amplification of granulocyte effector functions by a mechanism termed "priming." Although many studies have investigated the effects of granulocyte priming, little is known concerning the molecular mechanisms that lead to this phenomenon.

OBJECTIVE

The purpose of this study was to identify potential markers for granulocyte priming and thus also to gain further insight into the pathogenesis of inflammatory responses.

METHODS

We used a modified differential display technique, random arbitrary primed-PCR to identify genes regulated during the priming of human polymorphic nuclear granulocytes by GM-CSF in vitro. Genes identified were validated by Northern blot analysis of in vitro and in vivo primed leukocytes.

RESULTS

Several genes were identified and their expression characterized in vitro. One of these genes, 5-lipoxygenase-activating protein, was also found to be up-regulated in leukocytes isolated after allergen challenge of allergic asthmatic patients.

CONCLUSION

The use of differential display technology is a rapid and effective means of identifying genes whose expression is regulated by priming in vitro and in vivo. Further analysis will lead to a better understanding of the priming phenotype and may provide further insight into the pathologic mechanisms of inflammatory processes.

Perturbations in eosinophil homeostasis following treatment of lymphatic filariasis

Treatment of patients with patent Wuchereria bancrofti infection results in an acute clinical reaction and peripheral eosinophilia. To investigate the dynamics of the eosinophil response, changes in eosinophil activation and degranulation and plasma levels of eosinophil-active chemokines and cytokines were studied in 15 microfilaremic individuals in south India by sequential blood sampling before and after administration of 300 mg of diethylcarbamazine (DEC). Clinical symptoms occurred within 24 h. Plasma interleukin-5 (IL-5) and RANTES levels peaked 1 to 2 days posttreatment, preceding a peak peripheral eosinophil count at day 4. Major basic protein secretion from eosinophils paralleled IL-5 secretion, while levels of eosinophil-derived neurotoxin peaked at day 13 after treatment. Expression of the activation markers HLA-DR and CD25 on eosinophils rose markedly immediately after treatment, while expression of VLA-4 and alpha4beta7 showed an early peak within 24 h and a second peak at day 13. Thus, the posttreatment reactions seen in filarial infections can be divided into an early phase with killing of microfilariae, clinical symptomatology, increases in plasma IL-5 and RANTES levels, and eosinophil activation and degranulation and a later phase with expression of surface integrins on eosinophils, recruitment of eosinophils from the bone marrow to tissues, and clearance of parasite antigen.

Conditions in blood sampling procedures that extend the ex vivo stability of eosinophil activity markers in peripheral blood from allergic patients and healthy controls

BACKGROUND

Serum-ECP, EG2-epitope on intracellular ECP and surface expression of CD9 and CD11b in peripheral blood eosinophils (PBE) are considered to be markers that mirror clinical parameters in allergic inflammation.

OBJECTIVE

The aim was to investigate the impact of the blood sampling procedure on PBE markers and to identify optimal conditions for extended pre-analysis storage.

METHODS

Blood, from healthy individuals and patients with allergic rhinitis/asthma, was collected in tubes with EDTA, citrate, or without anti-coagulant. The expression of EG2-epitope, CD9, and CD11b were analyzed in eosinophils and neutrophils after 1, 5, and 24 hours of storage at +4 degrees C, according to the FOG-method and flow cytometry. In vitro stimulation with fMLP/PMA was used for metabolic activity analysis and CD11b mobilization. Following a 1-hour clotting period at +20 to 22 degrees C, samples were stored at +4 degrees C and serum-ECP levels were measured.

RESULTS

The EG2-epitope, serum-ECP, and CD9 were stable in samples from both healthy controls and allergic patients at all storage conditions. The EG2-epitope, serum-ECP and PBE count were significantly increased in the patient group, whereas no differences were observed in the expression of CD9 or CD11b. Both granulocytes and monocytes retained their metabolic activity for 24 hours. Neutrophils in citrate-blood increased their ability to respond to fMLP, as compared with EDTA-blood.

CONCLUSION

In vitro analysis of selected activity markers and functional tests could be performed on granulocytes from both healthy individuals and allergic patients after 24 hours storage at +4 degrees C. The anticoagulant citrate seems to be preferable to EDTA when monocytes or CD11b expression are analyzed.

Circadian variation of urinary eosinophil protein X in asthmatic and healthy children

BACKGROUND

It is suggested that urinary eosinophil protein X (EPX) is a noninvasive tool to monitor bronchial inflammation in asthmatic children. However, circadian variation of the number and activation of eosinophils might possibly influence urinary EPX excretion.

OBJECTIVE

Measurements of urinary EPX (radioimmunoassay) were used to investigate circadian variation of eosinophilic activation and to monitor bronchial inflammation in children with asthma before and after treatment with corticosteroids.

METHODS

Urinary EPX excretion (microg/mmol creatinine) was measured in the morning and afternoon in 22 stable asthmatics and in 16 nonatopic, nonasthmatic controls to investigate circadian variation. Additionally, EPX excretion in the afternoon was analysed in 21 children with chronic asthma before and after 6 weeks of treatment with inhaled corticosteroids, and in seven children within 24 h of admission due to an asthma exacerbation and again 3 months after discharge.

RESULTS

EPX excretion in the first morning urine sample of the day compared with the afternoon urine sample was significantly higher both in children with asthma (n = 22; mean +/- standard deviation: 179.7 +/- 97.3 vs 60.9 +/- 40.7 microg/mmol creatinine, P = 0.0001) and in nonatopic nonasthmatic controls (n = 16; 114.5 +/- 57.1 vs 53.4 +/- 29.0 microg/mmol creatinine, P = 0.0001). EPX excretion decreased significantly after 6 weeks of anti-inflammatory treatment in the group of children with chronic asthma (n = 21; 124.7 +/- 84.6 vs 87. 5 +/- 61.9 microg/mmol creatinine, P = 0.02) and in the group of children with an acute asthma exacerbation 3 months after discharge (n = 7; 233.2 +/- 174.5 vs 75.8 +/- 59.5 microg/mmol creatinine, P = 0.02).

CONCLUSION

This study suggests a circadian variation of EPX excretion in children with asthma and in nonatopic, nonasthmatic controls. Measurement of EPX excretion is helpful monitoring therapy in asthmatic children if circadian variation is considered.

Reduction of bioactive substances in stored donor blood: prestorage versus bedside leucofiltration

Leucocyte filtration has been suggested to improve transfusion products. We studied the effect of prestorage versus bedside leucofiltration on reduction of bioactive substances and leucocyte content in donor blood. Forty-five units of whole blood from healthy blood donors were studied. Of these units, 9 were stored under standard conditions for 35 d, 9 were leucofiltered after donation and then stored for 35 d, and 3x9 units were stored for 7, 21 and 35 d, respectively, before leucofiltration. Samples were collected from blood units immediately after donation, and before and after leucofiltration, and analysed by ELISA and RIA methods for extracellular content of myeloperoxidase (MPO), eosinophil cationic protein (ECP), histamine (HIS) and plasminogen activator inhibitor-1 (PAI-1). Leucocyte content was counted in all samples. In non-filtered blood extracellular MPO, ECP, HIS and PAI-1 were accumulated in a storage time-dependent manner, while prestorage leucofiltration prevented this accumulation. Leucofiltration after storage for 7, 21 or 35 d did not significantly reduce the accumulated bioactive substances, which were similar to levels in non-filtered blood stored for the same period of time. Prestorage and bedside leucofiltration on day 7 reduced the leucocyte content to less than 0.5x10(6)/L, whereas the median content in blood stored for 21 or 35 d was only reduced to 32.0 and 52.2x10(6)/L, respectively. Prestorage leucofiltration may thus be advantageous to bedside leucofiltration.

Ursodeoxycholic acid inhibits eosinophil degranulation in patients with primary biliary cirrhosis

Eosinophilia is a distinctive feature of primary biliary cirrhosis (PBC), especially in its early stages. Intriguingly, treatment with ursodeoxycholic acid (UDCA) ameliorates eosinophilia as well as liver tests in patients with PBC. It remains unknown, however, whether eosinophils in PBC patients are functionally activated and whether UDCA inhibits eosinophil activation. In the present study, we systematically examined eosinophil dynamics in the blood and liver in patients with stage I to II PBC before and after UDCA treatment. We determined serum concentrations of eosinophil granule proteins (major basic protein [MBP] and eosinophil-derived neurotoxin [EDN]) by radioimmunoassay and quantitated eosinophil degranulation using computer-assisted morphometry after MBP immunohistochemistry. Before UDCA treatment, patients with PBC (n = 25) showed significantly higher circulating eosinophil counts (P <. 05) and serum concentrations of MBP (P <.0005) and EDN (P <.02) compared with patients with chronic viral hepatitis (n = 22), autoimmune hepatitis (n = 10), and obstructive jaundice (n = 12). Four-week UDCA treatment significantly reduced blood eosinophil counts (P <.0001) and serum MBP (P <.0001) and EDN (P <.0001) levels in PBC patients. MBP immunohistochemistry and computer-assisted quantitative morphometry showed infiltration and degranulation of eosinophils in the portal tract in patients with PBC and significant reductions in the number of sites and the area occupied by extracellular MBP deposits after UDCA treatment for 2 years (P <.02) but not in placebo-treated patients. Our results suggest that eosinophils in patients with PBC are not only increased in number, but also release granule proteins, and that UDCA treatment inhibits this eosinophil activation/degranulation.

Eosinophil cationic protein in serum from nonatopic and asymptomatic atopic individuals after standardized blood clotting at 37 degrees C

Eosinophil cationic protein (ECP) and ECP/eosinophil ratio were measured in 223 apparently healthy subjects. The serum sample for ECP measurement was obtained by standardized clotting of the blood sample for 2 hours at 37 degrees C. Eosinophil count, ECP concentration and ECP/eosinophil ratio were no different between men (n = 122) and women (n = 101). Reference ranges for serum ECP and ECP/eosinophil ratio were 12-99 micrograms/L and 61-367 micrograms ECP per 10(9) eosinophils, respectively. Serum ECP and blood eosinophil count were positively correlated (y = 141x + 18, R2 = 0.45, P < 0.001). The ECP/eosinophil ratio, however, was found to decrease with increasing eosinophil count. Twenty-three per cent of the apparently healthy subjects were found to have a positive score for immunoglobulin E antibodies specific to inhalant allergens, and thus were considered atopic. Serum ECP concentrations and eosinophil counts were significantly higher in this group compared with the non-atopic group. In this healthy population no decision level for either eosinophil count, serum ECP or ECP/eosinophil ratio could be found that discriminated atopic from non-atopic individuals.

Basophil histamine release, IgE, eosinophil counts, ECP, and EPX are related to the severity of symptoms in seasonal allergic rhinitis

BACKGROUND

Serum specific IgE, basophil histamine release, and blood eosinophil parameters are associated with allergic rhinitis, but investigations of the relationship to the severity of allergic symptoms are few and conflicting. Our study aimed to investigate the seasonal changes in the following laboratory tests: specific IgE, basophil histamine release, eosinophil counts, and serum and plasma eosinophil cationic protein (ECP) and eosinophil protein X (EPX), and to analyze, in detail, the relationship of each individual test to the severity of symptoms in rhinitis patients allergic to both birch and grass pollen.

METHODS

The above tests were performed on blood samples obtained from 49 allergic rhinitis patients during the birch-pollen season, during the grass-pollen season, and after the seasons. Symptom-medication diaries were filled in during both pollen seasons. We used partial least square (PLS) analysis to establish an optimal statistical link between the symptom score and medication and the laboratory tests, in an investigator-independent way.

RESULTS

Increases in specific IgE, basophil histamine release, eosinophil counts, serum ECP and EPX, and plasma EPX were observed from the birch-pollen season to the grass-pollen season, followed by a decrease from the grass-pollen season to after the pollen seasons, except for the specific IgE. No seasonal changes in plasma ECP and total IgE were seen. The PLS analysis found a relationship between symptom score and medication and the aggregate laboratory tests (F-test value 40.2, correlation 0.34 for the cumulative relation). However, the variation in laboratory tests could explain only half of the total variation in symptoms and less than a quarter of the total variation in medication. The symptom score and, to a minor degree, medication were especially correlated with the basophil histamine-release results, with a decreasing relevance of specific IgE, eosinophil counts, total IgE, serum and plasma EPX, and serum ECP. Plasma ECP was not related to the symptom score and medication.

CONCLUSIONS

A significant relationship between the severity of allergic rhinitis and various allergic inflammatory markers was found but could account for only a minor part of the variation in the patients' evaluation of their disease.

Polymorphic eruption of pregnancy and herpes gestationis: comparison of granulated cell proteins in tissue and serum

Polymorphic eruption of pregnancy (PEP) and herpes gestationis (HG) are pregnancy-related dermatoses of unknown aetiology with eosinophil infiltration which, at early stages, may show similar clinical and histopathological features. To determine the relative contributions of eosinophils, neutrophils and mast cells to the pathogenesis of PEP and HG through deposition of granule proteins, we studied tissue and serum from 15 patients with PEP and 10 with HG. Using indirect immunofluorescence with antibodies to human eosinophil granule major basic protein (MBP), eosinophil-derived neurotoxin (EDN), eosinophil cationic protein (ECP), neutrophil elastase and mast cell tryptase, we determined and compared cellular and extracellular staining patterns in lesional skin biopsy specimens and, using immunoassay, measured MBP, EDN, and ECP in patients' sera. Eosinophil infiltration and extracellular protein deposition of all three eosinophil granule proteins were present in both PEP and HG indicating a pathogenic role for eosinophils in both diseases. Staining for eosinophil granule proteins was especially prominent in urticarial lesions and around blisters in HG. EDN and ECP serum levels in PEP and ECP serum levels in HG were significantly increased compared with those in normal pregnant and normal nonpregnant serum. Neutrophils were more prominent in HG specimens than in PEP specimens; extracellular neutrophil elastase was minimally present and similar in both diseases. Mast cell numbers and extracellular tryptase deposition did not differ between the two diseases and did not differ from mast cell counts in skin of normal pregnant women. This study shows that eosinophil granule proteins are deposited extracellularly in tissue and are increased in serum in both PEP and HG. Moreover, eosinophil involvement in the two diseases is more consistent than neutrophil and mast cell involvement. Comparatively, tissue eosinophil infiltration and extracellular protein deposition is more extensive in HG than in PEP, suggesting that eosinophil involvement is greater in the pathogenesis of HG than PEP and similar to that found in bullous pemphigoid.

Increased eosinophil activity in acute Plasmodium falciparum infection--association with cerebral malaria

To assess the eosinophil response to Plasmodium falciparum infection a cohort of initially parasite-free Ghanaian children was followed for 3 months. Seven of nine children who acquired an asymptomatic P. falciparum infection showed increase in eosinophil counts, while a decrease was found in seven of nine children with symptomatic malaria, and no change was observed in 14 children who remained parasite-free. In a hospital-based study, paediatric patients with cerebral malaria (CM), severe anaemia (SA), or uncomplicated malaria (UM) had uniformly low eosinophil counts during the acute illness followed by eosinophilia 30 days after cure. Plasma levels of eosinophil cationic protein (ECP) and eosinophil protein X (EPX) were measured as indicators of eosinophil activation. In spite of the low eosinophil counts, ECP levels were increased on day 0 and significantly higher in patients with CM (geometric mean (95% confidence interval) 8.5 ng/ml (6.8-10.7 ng/ml)) than in SA (4.7 ng/ml (3.0-7.5 ng/ml)) and UM patients (4.3 ng/ml (3.6-5.3 ng/ml), P < 0.001). A similar pattern was found for EPX. It thus appears that the low eosinophil counts may be due to tissue sequestration and destruction rather than decreased production. The plasma levels of the granule proteins correlated with levels of tumour necrosis factor and soluble IL-2 receptor, implicating inflammatory responses and T cell activation as causes of the eosinophil activation. By contrast, the eosinophil induction did not appear to be part of a Th2-like response. Eosinophil granule proteins may be important in both control of malaria infection and the pathogenesis of severe malaria.

Clinical utility of serum levels of eosinophil cationic protein (ECP) for monitoring and predicting clinical course in childhood asthma

BACKGROUND

The concentration of ECP in serum has been proposed as a marker of airway inflammation in asthma. However, its clinical significance is still to be determined.

OBJECTIVES

This study was performed to determine whether concentration of ECP in serum reflects clinical status in asthma and can serve as a predictive parameter.

METHODS

Cross-sectional analysis was performed in 28 children with asthma. A total of 91 blood samples was obtained to determine levels of ECP in serum and eosinophil counts. Forced expiratory volume in 1 s was also determined at the time of the sampling. Data were analysed on the basis of asthma symptoms in the 4 weeks before and the 4 weeks after sampling.

RESULTS

Serum levels of ECP were significantly lower in patients who had been asymptomatic for 3 or 4 weeks before sampling than in patients who had been symptomatic or asymptomatic for only 1 or 2 weeks. In the former group, serum levels of ECP were higher when patients became symptomatic after sampling than when they remained stable, a finding that suggests that serum levels of ECP may have a predictive value in certain situations. Although the concentration of ECP in serum was not proved to be predictive in the latter symptomatic group, the concentration of ECP was significantly lower when measured again 4 weeks later when the patients' symptoms had resolved. In contrast, levels of ECP were unchanged when patients remained symptomatic, a finding that suggests serum levels of ECP may reflect the clinical response to therapy.

CONCLUSIONS

Serum ECP may be a useful marker for monitoring and predicting the clinical course in asthma.

Urinary eosinophil-derived neurotoxin/protein X: a simple method for assessing eosinophil degranulation in vivo

BACKGROUND

Eosinophil-derived neurotoxin/protein X (EDN/EPX), one of the cationic granule proteins released by polymorphonuclear eosinophils, can be detected in human urine.

OBJECTIVE

We sought to evaluate whether the urinary release of EDN/EPX was dependent on the blood eosinophil cell count, the bronchoalveolar eosinophil cell count, or both and on the clinical diagnosis. We also attempted to determine the precise kinetics of decrease of EDN excretion and eosinophil counts after the onset of corticosteroid treatment.

METHODS

Daily urinary release of EDN/EPX was measured by radioimmunoassay in 28 patients with high hypereosinophilia (group 1), 32 patients with moderate hypereosinophilia (group 2), 26 patients without hypereosinophilia at the time of the study but with a known pulmonary disease involving eosinophils (group 3), and 13 control patients (group 4).

RESULTS

The urinary excretion of EDN/EPX was significantly higher in patients from groups 1 or 2 than in patients from groups 3 or 4. Particularly high levels of EDN/EPX excretion were observed in patients from groups 1 or 2 with chronic eosinophilic pneumonia (chronic eosinophilic pneumonia: 4.7 +/- 8.1 mg/day, control subjects: 0.39 +/- 0.33 mg/day, p < 0.001). Urinary excretion of EDN/EPX was significantly correlated with blood (r = 0.66, p < 0.001) and differential bronchoalveolar (r = 0.62, p = 0.04) eosinophil cell counts in patients from group 1 but not from the other groups. Corticosteroid treatment was followed by a significant decrease in EDN/EPX excretion. The kinetics of decrease in EDN/EPX were delayed as compared with the dramatic drop in peripheral eosinophil counts. Distinct kinetics between urinary EDN/EPX and eosinophil counts differentiated the recurrence of chronic eosinophilic pneumonia from an asthma attack in one patient.

CONCLUSION

Measurement of urinary EDN/EPX excretion may be a useful indicator of eosinophil degranulation in vivo.

Effect of heating on extracellular bioactive substances in stored human blood: in vitro study

BACKGROUND

We have previously shown extracellular accumulation of various leukocyte and platelet-derived bioactive substances in human blood during storage. Release of bioactive substances may be temperature-dependent, and we studied the effect of heating during in vitro transfusion on bioactive substance accumulation in stored human blood.

METHODS

Eight units of whole blood and eight units of prestorage leukofiltered whole blood were stored at 4 degrees C for 7 days. Subsequently, the blood from all 16 units was transfused via a blood-heating device, which increased the blood temperature to 37 degrees C at outlet. Samples for enzyme-linked immunosorbent assay or radioimmunoassay analyses of histamine, myeloperoxidase (MPO), eosinophil cationic protein (ECP), and plasminogen activator inhibitor-1 (PAI-1) were drawn from the units at donation, after 7 days of storage just before transfusion, and during the in vitro transfusion.

RESULTS

Extracellular concentrations of histamine, MPO, ECP, and PAI-1 were significantly (p < 0.05) increased in nonfiltered whole blood stored for 7 days compared with concentrations in fresh donated blood and in prestorage leukofiltered whole blood stored for 7 days. Heating reduced histamine, MPO, and ECP concentrations significantly (p < 0.05) in nonfiltered whole blood, whereas PAI-1 concentrations increased significantly (p < 0.05). Finally, there was no difference in concentrations of histamine, MPO, ECP, and PAI-1 in samples collected before and after heating of leukofiltered whole blood.

CONCLUSIONS

Heating reduces accumulation of extracellular leukocyte-derived bioactive substances in whole blood, whereas it increases platelet-derived substances. Prestorage leukofiltration, however, reduces the obligatory extracellular accumulation of leukocyte and platelet-derived bioactive substances, which in addition is unchanged by heating.

Eosinophil protein X concentration is dependent on eosinophil concentration

The relationship between the eosinophil concentration and the serum eosinophil protein X concentration was investigated in 80 subjects. Higher eosinophil counts resulted in obviously increased serum eosinophil protein X concentrations. However, the amount of eosinophil protein X released per eosinophil granulocyte is significantly higher in subjects with lower eosinophil counts. Atopic subjects (N = 19) show a significantly higher eosinophil concentration (p = 0.002) and eosinophil protein X concentration (p = 0.004) and a significantly lower eosinophil protein X/eosinophil ratio (p = 0.02), compared with non-atopic subjects (N = 61). However, there appears to be no difference between the concentration of eosinophil protein X in atopic and non-atopic subjects if the eosinophil concentration is taken into account. When using eosinophil protein X as an indicator of eosinophil activation, for instance in asthmatic subjects, the eosinophil count should also be considered for correct clinical interpretation of results.

Blood sample processing effect on eosinophil cationic protein concentration

BACKGROUND

Asthma is considered to be an inflammatory disease. The most important cell involved in the inflammation is the eosinophil. These cells and their mediators, such as eosinophil cationic protein (ECP), are potential markers of the inflammation's severity. Eosinophil cationic protein may be used for monitoring antiasthma treatment. It is well known that sample processing conditions can affect the ECP blood levels.

OBJECTIVE

The aim of this work is to study the effect of temperature, time, and anticoagulants on ECP levels.

METHODS

We studied five asthmatic patients and five healthy controls. We obtained three different blood samples from each subject, one with heparin, one with EDTA, and one without anticoagulant. To evaluate the effect of temperature, serum samples were clotted for an hour, one at 0 degree C, one at room temperature, and the other at 37 degrees C. Plasma (heparin and EDTA) samples were treated as follows: one was immediately centrifuged, and two were stored for an hour, one at 0 degree C, and the other at room temperature. Eosinophil cationic protein levels were measured by fluoroimmunoassay (CAP-System ECP FEIA Pharmacia).

RESULTS

A higher temperature during blood clotting resulted in a higher ECP concentration. There were no differences between ECP determination in serum samples and plasma samples with heparin, under the same conditions of time and temperature; so clotting may not be necessary for ECP release in vitro. Eosinophil cationic protein was not released in plasma samples with EDTA, neither at 0 degree C nor room temperature.

CONCLUSIONS

More studies must be done to clarify the mechanism of the ECP release in vitro.

Individual time-courses of ECP and EPX during allergen provocation tests in asthmatic children

To study the time-course of eosinophil cationic protein (ECP) and eosinophil protein X (EPX) during bronchial allergen provocation, we investigated 32 asthmatic children sensitive to house-dust mites as well as 6 non-atopic young adult controls. In all subjects, allergen challenges were performed with house dust mite extracts of Dermatophagoides pteronys-sinus or Dermatophagoides farinae. Blood samples were taken at regular intervals during the 24-h observation period. The individual time-courses of ECP and EPX revealed different characteristic groups of patterns: (1) an isolated early serum peak of both mediators during or within the first 60 min after provocation (2) an early plus a late peak (3) an isolated late peak 12 h after provocation (4) an isolated late peak 24 h after provocation, and (5) no significant variation during the 24-h observation period. The early peak could be due to short-term changes in eosinophil activation, while late peaks may reflect eosinophil proliferation, recruitment, subsequent priming and enhancing of the propensity to release their proteins. ECP and EPX showed a corresponding parallel time-course in nearly all challenges, with EPX-concentration exceeding that of ECP. There was no correlation between ECP/EPX serum concentrations and clinical parameters such as lung function data. From our results we conclude that the striking groups of time-courses of ECP/EPX serum concentration indicate different uniform patterns of eosinophil activation during allergen challenge-but do not predict clinical outcome of provocation. The role of the eosinophil in early asthmatic reactions remains to be established in further studies.