Prolonged Endurance Challenge at Moderate Altitude* Effect on Serum Eosinophil Cationic Protein, Eosinophil Dynamics, and Lung Function Wolfgang Domej, MD; Gu¨nther Schwaberger, MD; Gernot Peter Tilz, MD, FCCP; Zeno Fo¨ldes-Papp, MD, PhD; Ulrike Demel, MD; Johanna Lang, PhD; and Serge Petelin von Duvillard, PhD
Background: Eosinophils contain granule proteins such as eosinophil cationic protein (ECP) that have proinflammatory effects on airways. ECP may be released on activation of eosinophils into the plasma and is widely used as a marker of bronchial hyperreactivity and allergic inflammation. Environmental factors as well as intense physical exertion may influence eosinophil-related bronchial hyperreactivity. Study objectives: To investigate the effect of endurance exercise at moderate altitude on levels of circulating eosinophils, serum ECP, serum osmolality (sOS), and dynamic pulmonary function parameters in healthy mountaineers. Setting: Alpine field study performed in the Alps of Upper Styria in Austria. Type of exercise: Ascent of a mountain at maximal speed. Participants: Thirty healthy male volunteers from a troop of military mountaineers. Results: Mean ECP concentration increased by 66% at the summit checkpoint (H2) and remained at 63% above baseline (base checkpoint [H0]) after descent (H4), while the blood eosinophil count decreased concomitantly from 250/L at H0 (preexercise) to 118/L (53%) at H2 and to 22/L (81%) at H4. The total serum ECP concentration adjusted to sOS correlated negatively with blood eosinophil count (r ⴝ ⴚ 0.37; p < 0.0001) and PaO2 (r ⴝ ⴚ 0.34; p < 0.001), but positively with the peak expiratory flow (PEF) [r ⴝ 0.45; p < 0.0001]. Although sOS correlated with serum ECP at H2 (r ⴝ 0.47; p ⴝ 0.02) and at 12 h after the start of the experiment (H12) [r ⴝ 0.57; p ⴝ 0.003], the relationship between total ECP and sOS (r ⴝ 0.19; p ⴝ 0.034) was less pronounced. FEV1 in percentage of FVC (%FEV1/FVC) [the Tiffenau test], forced expiratory flow rate at 25% of vital capacity, and PEF were significantly higher at H2 than at H0 and H4. %FEV1/FVC decreased to 88% (p < 0.01) and 83% (p < 0.001) predicted at H12 and 24 h after start of the experiment, respectively. Conclusion: Results provide strong evidence for nonspecific activation of blood eosinophils during prolonged intense aerobic exercise at moderate altitude, modifying both eosinophil dynamics and regulation of ECP release in healthy subjects. (CHEST 2002; 121:1111–1116) Key words: endurance exercise; eosinopenia; eosinophil cationic protein; eosinophil dynamics; lung function; moderate altitude; nonallergic eosinophil cationic protein release; serum osmolality Abbreviations: ECP ⫽ eosinophil cationic protein; EIA ⫽ exercise-induced asthma; %FEF25/VC ⫽ forced expiratory flow rate at 25% of vital capacity; %FEV1/FVC ⫽ FEV1 in percentage of FVC; H0 ⫽ base checkpoint; H2 ⫽ summit checkpoint; H4 ⫽ after descent; H12 ⫽ 12 h after start of the experiment; H24 ⫽ 24 h after start of the experiment; PEF ⫽ peak expiratory flow; sOS ⫽ serum osmolality
osinophil granule-derived proteins such as eosinE ophil cationic protein (ECP) are considered important in the pathogenesis of allergic inflammation.1,2 When eosinophils degranulate in response to *From the Department of Internal Medicine (Dr. Domej), Institute of Physiology (Dr. Schwaberger), Clinical Immunology and Jean Dausset Laboratory (Drs. Tilz, Fo¨ldes-Papp, and Demel), Graz University M. S. and Hospital, Graz, Austria; Lang Consulting (Dr. Lang), Fremont, CA; and Human Performance Laboratory (Dr. von Duvillard), Department of Physical Education and Exercise Science, University of North Dakota, Grand Forks, ND. www.chestjournal.org
inhaled allergens, cytotoxic granule proteins are released. In asthma, ECP is released in response to allergen-IgE crosslinking in the bronchial wall.1 SeMundipharma Austria, Leopold Pharmaceutical Company, and AVL Medizintechnik, Graz, provided financial support. Manuscript received January 18, 2001; revision accepted October 3, 2001. Correspondence to: Gernot Peter Tilz, MD, FCCP, Director, Clinical Immunology and Jean Dausset Laboratory, Graz University M. S. and Hospital, Auenbruggerplatz 8, A-8036 Graz, Austria; e-mail:
[email protected] CHEST / 121 / 4 / APRIL, 2002
1111
rum ECP is regarded as a highly sensitive indicator of eosinophil activation and, by extension, of the degree of bronchial hyperresponsiveness.3,4 The concentration of serum ECP usually correlates with activation of eosinophils in vivo. Eosinophils carrying cytotoxic peptides are known to mediate damage to the respiratory epithelium.5 Deposition of ECP and other granule proteins is also known to play an important role in the shedding of bronchial epithelium, which may lead to inflammatory asthmatic tissue damage.5,6,7 Correspondingly, studies using BAL revealed that BAL ECP correlates with the severity of lung damage and hypoxemia in patients with ARDS.8 However, it has been shown that blood eosinophils may also be activated by nonallergic mechanisms. Venge et al9 also observed an initial short-term rise in serum ECP in patients with exercise-induced asthma (EIA) after exercise challenge, but no change in serum ECP levels in asthmatics without EIA. Tsuda et al10 found that ECP levels in asthmatic children may rise during exercise and that this increase may even continue after exercise, but only in the EIA-positive group. Dufaux et al11 found an increase in ECP release after short, maximal bicycle exercise in healthy subjects, providing strong evidence that blood eosinophils may be activated after a short bout of maximal exercise. Varying release of eosinophil granule proteins has been previously reported in response to environmental factors.12 Altitudinal environmental factors such as tropospheric ozone may cause subclinical airway inflammation and temporarily increase bronchial responsiveness, even in healthy adults.13 Moreover, ECP was found to be released on short maximal physical exertion, most likely due to a nonallergic mechanism of activation.11 In vivo data on nonimmunologic eosinophil activation are rare in the literature. There are only limited data on the mechanical properties, osmotic behavior, and stability of eosinophils,4 particularly in response to the physiologic challenge of altitude-related hypoxia and concomitant endurance exercise.
Table 1—Physical Characteristics and Performance Data* Variables
Data
Age, yr Height, cm Weight, kg Body mass index Additional weight, kg Time of ascent, min Time of descent, min
34 ⫾ 8 (24–49) 178 ⫾ 5 (170–186) 76 ⫾ 7 (61–96) 24 ⫾ 1 (19–25) 15 ⫾ 1.5 (12–19.5) 170 ⫾ 30 (130–230) 34 ⫾ 8 (35–50)
*Data are presented as mean ⫾ SD (range).
about 2,000 calories of food daily (75% carbohydrates, 15% fat, and 10% protein). Fluids were freely available immediately before but not during exercise. During ascent and descent, subjects carried a standard load of 20% of their individual body weight (12 to 19.5 kg). For blood sampling at the checkpoints, a venous cannula (TriCath; Codan; Espergaerde, Denmark) was inserted before the trial and filled with 1 mL of heparinized 0.9% sodium chloride. Starting from the base checkpoint (H0) at 632 m (Aigen, Styria, Austria), all participants climbed a mountain (Mount Grimming; Fig 1) to the summit checkpoint (H2) at 2,351 m above sea level. A schematic altitude profile is shown in Figure 2. Participants started their ascent at 10-min intervals. The first kilometer of the trail went up a gentle slope and provided a moderate warm-up, after which subjects increased their climbing pace to their maximal individual capacity and maintained that pace until they arrived at H2. After a 30-min rest period, they returned to H0 as quickly as possible. Clinical Variables and Dynamic Lung Function Parameters Laboratory data including serum ECP, serum osmolality (sOS), blood eosinophil count, and Pao2; lung function parameters were measured 30 min before exercise at H0, immediately after arrival at H2, after descent (H4), at 12 h after the start of the experiment (H12), and at 24 h after the start of the experiment (H24). Venous blood samples were drawn under anaerobic conditions using Vacutainer tubes (Plymouth, UK) at checkpoints along the ascent route. Samples were allowed to clot at room temperature for 60 min and were centrifuged at 2,000g for 10 min. Thereafter,
Materials and Methods Course of the Study Thirty healthy and physically fit male volunteers were recruited from a troop of military mountaineers; the demographics of these volunteers are given in Table 1. All subjects gave written informed consent and underwent a general health and physical fitness assessment 2 weeks before the study. Asthma or reactive airway diseases were ruled out at this time. Exclusion criteria also included ongoing medical treatment, acute or chronic disease, or physically limiting injuries. Subjects were asked to abstain from intense physical exercise 3 days before the start of the study. Food intake was standardized, and all participants consumed 1112
Figure 1. Profile of the mountain. Clinical Investigations
ⱖ 80% ⱖ 80%
⬍ 300 ⱖ 80%
280 81 86.2 580 90 280 ⫾ 9 (⬍ 0.81) 83 ⫾ 7 (⬍ 0.0001) 87.4 ⫾ 5.9 (⬍ 0.5) 566 ⫾ 93 (⬍ 0.11) 98 ⫾ 26 (⬍ 0.05) 287 90 87.5 610 71 284 ⫾ 12 (⬍ 0.05) 88 ⫾ 8 (⬍ 0.012) 91.0 ⫾ 11.1 (⬍ 0.05) 616 ⫾ 87 (⬍ 0.09) 80 ⫾ 22 (⬍ 0.05) 292 93 78.9 652 90 293 ⫾ 7 (⬍ 0.0001) 93 ⫾ 13 (⬍ 0.32) 79.8 ⫾ 6.2 (⬍ 0.001) 668 ⫾ 122 (⬍ 0.06) 99 ⫾ 31 (⬍ 0.1) 289 98 62.6 768 108 281 91 85.1 615 90 279 ⫾ 5 92 ⫾ 10 86.6 ⫾ 6.3 622 ⫾ 131 97 ⫾ 27 mOsmol/kg % mm Hg L/min % predicted
288 ⫾ 8 (⬍ 0.001) 101 ⫾ 15 (⬍ 0.0001) 63.4 ⫾ 6.2 (⬍ 0.0001) 765 ⫾ 123 (⬍ 0.0001) 121 ⫾ 34 (⬍ 0.0001)
2.3–16 100–600 3.3 200 4.4 ⫾ 2.6 (⬍ 0.54) 262 ⫾ 145 (⬍ 0.21) 3.6 200 4.2 ⫾ 2.0 (⬍ 0.29) 237 ⫾ 167 (⬍ 0.61) 5.2 000 6.2 ⫾ 3.2 (⬍ 0.0001) 22 ⫾ 42 (⬍ 0.0001) 6.2 100 6.3 ⫾ 2.2 (⬍ 0.0001) 118 ⫾ 62 (⬍ 0.001) 3.3 200 3.8 ⫾ 1.7 250 ⫾ 182
Median Mean ⫾ SD (p Value) Median Mean ⫾ SD (p Value) Mean ⫾ SD Median
g/L cells/L
Serum ECP Eosinophil count Osmolality %FEV1/FVC Pao2 PEF %FEF25/VC
Reference Range Mean ⫾ SD (p Value)
Median www.chestjournal.org
U
The ascent to H2 took 130 to 230 min (mean ⫾ SD, 170 ⫾ 30 min), while the descent to H0 took 35 to 50 min (34 ⫾ 8 min; Table 1). The mean lactate concentration measured at H2 was far below the inflection point of 4 mmol/L, indicating aerobic endurance challenge during ascent. However, the lactate concentration rose slightly from 1.1 mmol/L prechallenge (at H0) to 2.7 mmol/L after arrival at H2.
Variables
Results
Mean ⫾ SD (p Value)
Median
H24 H12 H0
All statistical data given in Tables 1 to 4 were calculated on a personal computer and analyzed using software (StatView 4.5; Abacus Concepts; Berkeley, CA). Data were expressed as mean ⫾ SD. Differences between the checkpoints were tested for significance using Wilcoxon’s signed rank test. Relationships between laboratory and lung function parameters were assessed by Pearson product moment correlation coefficients. Values of p ⬍ 0.05 were considered significant.
H4
Statistics
H2
the sera were stored at 5°C in refrigerated chests before processing at the Karl-Franzens University School of Medicine in Graz. Serum ECP concentrations were determined by a radioimmunoassay technique (ECP-RIA; Pharmacia; Stockholm, Sweden) as described by Petersen et al.14 All concentrations were corrected for changes in plasma volume calculated from the sOS (normal values 280 to 300 mOsmol/kg), which was measured by osmometry (Fiske 100 Osmometer; Fiske Associates; Norwood, MA). Serum ECP was considered normal within the range of 2.3 to 16 g/L. Blood eosinophil counts (normal range, 180 to 600/L) were assessed by volume conductivity and scatter technology (STKS; Beckman Coulter; Miami, FL). Blood lactate concentration was measured from an earlobe blood sample (EBIO⫹; Eppendorf; Hamburg, Germany), and arterial blood gases were sampled from the radial artery (AVL Micropuncture Set; AVL ⫽ List Medizintechnik; Graz, Austria) at each checkpoint of the trial according to a standardized method. Heparinized blood gas vials were refrigerated at 5°C and analyzed within 60 min after sampling in an automatic blood gas analyzer (AVL 995 Hb). Results were corrected for local atmospheric pressure and temperature. Pulmonary function was assessed using mobile batterydriven and flow-calibrated pneumotachographs at each of the checkpoints (Multispiro 100; Medical Graphics Corporation; St. Paul, MN); the devices were automatically calibrated for ambient temperature and atmospheric pressure. The best of three repeated flow-volume maneuvers was recorded.
Table 2—Laboratory and Respiratory Variables in Subjects at Study Time Points H0 to H24
Figure 2. Schematic profile of the trail, time intervals, and checkpoints.
CHEST / 121 / 4 / APRIL, 2002
1113
Clinical Laboratory Parameters Clinical laboratory results and lung function data at all checkpoints are presented in Table 2. sOS values and concentrations of serum ECP remained within normal limits at all checkpoints. Blood eosinophils decreased by 53% from checkpoints H0 to H2 (p ⬍ 0.0004), by 81% from H2 to H4 (p ⬍ 0.0001), and returned to normal at H12 (Table 2). In contrast, serum ECP levels rose significantly (66%) from H0 to H2 (p ⬍ 0.0001) and remained elevated at H4 by 63% (p ⬍ 0.0001). During recovery and rehydration (H12 to H24), serum ECP returned to near-baseline levels. sOS rose by 3% from H0 to H2 (p ⬍ 0.001) and by 5% at H4 (p ⬍ 0.0001). At H12, sOS was still significantly higher than H0 (p ⬍ 0.05), but returned to normal after sufficient rehydration at H24 (280 ⫾ 9 mOsmol/kg). sOS was significantly correlated to ECP at all checkpoints (H2, H4, H12, and H24). There was also a weak but significant correlation between cumulative serum ECP and sOS (r ⫽ 0.19, p ⬍ 0.04; Table 3). A strong correlation among these variables was found only for cumulative serum ECP and eosinophils (r ⫽ ⫺ 0.37, p ⬍ 0.0001). Furthermore, serum ECP was strongly correlated to the peak expiratory flow (PEF) at H0, H2, and H4 (Table 4). Ventilatory Response and Ventilatory Parameters The cumulative FEV1 in percentage of FVC (%FEV1/FVC) [the Tiffenau test] correlated weakly with sOS (p ⬍ 0.02) but not with serum ECP (r ⫽ 0.07, p ⬍ 0.5; Table 3). %FEV1/FVC rose from 92 ⫾ 10% predicted at H0 to 101 ⫾ 15% at H2 (p ⬍ 0.0001) and returned to near-baseline levels at H4 (93 ⫾ 13%, p ⬍ 0.32). The postexercise %FEV1/ FVC decreased to 88% (p ⬍ 0.01) and 83% (p ⬍ 0.0001) of the predicted values at H12 and H24, respectively. The PEF rate increased significantly by 23% from H0 to H2 (p ⬍ 0.0001). There was a 130% increase in respiration rate from H0
Table 3—Correlations Between the Cumulative Laboratory Values, Pulmonary Function Parameters (¥ H0 –H24) and Serum ECP X-Axis, Serum-ECP (H0 to H24) Y-Axis
r
p Value
sOS %FEV1/FVC Pao2 %FEF25/VC Blood eosinophil count PEF
0.19 0.07 ⫺ 0.33 0.31 ⫺ 0.37 0.45
⬍ 0.04 ⬍ 0.48 ⬍ 0.001 ⬍ 0.001 ⬍ 0.0001 ⬍ 0.0001
1114
Table 4 —Relationship Between Serum ECP and %FEV1/FVC, sOS, PaO2, Eosinophil Count, and PEF* X-Axis Y-Axis sOS ECP Pao2 EO PEF %FEV1/FVC Pao2 ECP EO PEF %FEV1/FVC sOS Blood eosinophil count ECP Pao2 PEF %FEV1/FVC sOS PEF ECP Pao2 EO %FEV1/FVC sOS %FEV1/FVC ECP Pao2 EO PEF sOS Serum ECP Pao2 EO PEF sOS %FEV1/FVC
r, H0
r, H2
r, H4
r, H12
r, H24
0.02 0.29 0.04 0.46 0.05
0.47 0.28 0.12 0.09 0.54
0.33 0.08 0.01 0.27 0.04
0.57 0.32 0.25 0.41 0.33
0.33 † 0.48 0.07 0.39
0.01 0.14 0.10 0.08 0.29
0.15 0.28 0.10 0.21 0.28
0.10 0.14 0.11 0.26 0.08
0.17 0.36 0.01 0.42 0.32
0.30 0.14 0.34 0.13 0.04
0.04 0.28 0.02 0.13 0.12
0.04 0.14 0.32 0.20 0.01
0.25 0.36 0.29 0.04 0.25
0.29 † 0.43 0.05 0.48
0.52 0.10 0.34 0.31 0.46
0.40 0.10 0.02 0.07 0.09
0.33 0.11 0.32 0.08 0.27
0.11 0.01 0.29 0.20 0.41
0.10 † 0.43 0.15 0.07
0.25 0.08 0.13 0.31 0.05
0.06 0.21 0.13 0.07 0.54
0.13 0.26 0.20 0.08 0.04
0.52 0.42 0.04 0.20 0.33
0.21 † 0.05 0.15 0.39
0.01 0.30 0.52 0.02 0.25
0.15 0.04 0.40 0.47 0.06
0.10 0.04 0.33 0.33 0.13
0.17 0.25 0.11 0.57 0.52
† 0.29 0.10 0.39 0.21
†
*EO ⫽ eosinophil count. †Arterial blood gas examination refused by most of the subjects at H24.
(17 ⫾ 3 breaths/min) to H2 (39 ⫾ 7 breaths/min), which remained elevated at H4 (30 breaths/min, ⫹ 76%), and H12 (24 breaths/min, ⫹ 41%). The cumulative serum ECP concentration, the sum of serum ECP concentrations of all subjects at checkpoints H0 to H24, correlated significantly with Pao2 (r ⫽ 0.33, p ⬍ 0.001; Fig 3) and with PEF (r ⫽ 0.45, p ⬍ 0.0001; Table 3, Fig 4). Figure 5 is a graphical summary of the main results correlating blood eosinophil count, ECP in serum, and %FEV1/FVC at all checkpoints (H0 to H24). Discussion Mountaineering is a popular recreational activity, and remote sites at moderate and high altitudes are Clinical Investigations
Figure 3. Cumulative serum ECP concentration in relation to Pao2.
becoming increasingly accessible to the public. Unlike athletes who undergo altitude-training regimens, recreational mountaineers are often not acclimatized. Our study specifically investigated effects of mountaineering (a prolonged endurance challenge) in nonacclimatized subjects. We observed a severe drop in the blood eosinophil count accompanied by a drastic increase in serum ECP following endurance exercise at moderate altitude (Fig 5). Our data also provide evidence of moderate generation of bronchial hyperreactivity reflected as a transient ECP increase during exercise, and a delayed, significant decrease in %FEV1/ FVC during the recovery period (Table 2). Our endurance exercise study involved intense, prolonged mouth breathing of cold, dry air. Under these circumstances, the inhaled air cannot be conditioned by the upper airways and this task is shifted to the peripheral airways. We propose that increased respiratory water loss dehydrates the perciliary fluid; the increased osmolality then indirectly triggers the re-
Figure 4. Cumulative serum ECP concentration in relation to PEF.
www.chestjournal.org
Figure 5. Correlations between serum ECP, blood eosinophil count (EO), and %FEV1/FVC (Tiffenau test) at given time points.
lease of ECP from eosinophils via an osmotic challenge to the bronchial epithelium. Our data suggest a subclinical, nonallergic inflammation within the airways leading to an increase in bronchial reactivity. Lung function measurements during the study showed that the %FEV1/FVC was generally unaffected during exercise, but decreased significantly during the recovery period. We suggest that airway resistance increased as a delayed response to eosinophil degranulation products and that the deterioration of the dynamic lung function parameters, %FEV1/FVC, PEF, and forced expiratory flow at 25% of vital capacity (%FEF25/VC) during the recovery period (H12 to H24), is due to increased airway resistance rather than respiratory muscle fatigue. It is possible that during exercise, the airflow was improved due to the lower air density at altitude and that this effect compensated for or exceeded any increase in airway resistance during the exercise period, so that the %FEV1/FVC remained substantially unaffected until the recovery period. It has been shown that circulating eosinophils are attracted to the airway mucosa by enhanced cytokine and mediator release15 from activated bronchial epithelial cells, principally by interleukin-516 and tumor necrosis factor-␣. An enhanced migration of blood eosinophils to airway tissues can explain the marked eosinopenia during and immediately after the endurance challenge. Similar profound drops in the blood eosinophil count down to complete disappearance of eosinophils from the circulation have been described in acute inflammatory conditions,17 acute physiologic stress,4 and physical exercise.18,19 In contrast to these findings, Gabriel et al20 reported increased circulating eosinophils after short supramaximal exercise on a bicycle ergometer; this may be explained by mobilization of eosinophils due to the short duration of
CHEST / 121 / 4 / APRIL, 2002
1115
the physical effort. Investigations by Venge et al3 clearly point out a positive relationship between serum ECP concentrations and cellular damage to airway tissue in patients with severe asthma. While the effect of relapsing episodes of nonallergic ECP rise on the expression of bronchial hyperreactivity in healthy subjects has not been established, it is conceivable that frequent episodes of ECP peaks create a higher risk for developing exercise-induced and allergic asthma. Recurrent enhancements of eosinophil adhesion, migration, and release may even cause high-altitude cough or high-altitude pulmonary edema. An increase in serum ECP may also be involved in the rise of vascular permeability at altitude due to liberation of histamine from mast cells and eosinophils,21 causing acute altitude-related disorders. Although a potential link between tissue eosinophils and plasma exudation mechanisms in vivo has been observed,22 such a relationship remains speculative. In summary, our results may indicate a general relationship between strenuous endurance exercise and ECP release from eosinophils. We acknowledge that in addition to the mechanism we propose, environmental factors could have had additive systemic effects on ECP release and may have enhanced the propensity of eosinophils to degranulate in our healthy subjects. Whether prolonged exerciseinduced hyperventilation in a dry, hypoxic, and cold environment can lead to a certain type of airway pathology remains unclear. ACKNOWLEDGMENT: We thank Franz Berghold, MD, and Peter Hofmann, PhD, for help in performing this field study; and Bettina Scharfetter, MD, Sabine Fleck, MD, Elisabeth Irgolic, Renate Moser, MD, Hannelore Maurer, and Gerlinde Schnabl, for performing lung function tests and obtaining blood samples. We also thank the military helicopter base of the Austrian Bundesheer, Aigen/Ennstal, for assistance and organizational support; and Eugenia Lamont, BA, for final review of the manuscript.
5
6
7
8
9 10
11 12 13 14
15 16 17 18 19
References 1 Erjefalt JS, Greiff L, Andersson M, et al. Allergen-induced eosinophil cytolysis is a primary mechanism for granule protein release in human upper airways. Am J Respir Crit Care Med 1999; 160:304 –312 2 Beppu T, Ohta N, Gon S, et al. Eosinophil and eosinophil cationic protein in allergic rhinitis. Acta Otolaryngol Suppl 1994; 511:221–223 3 Venge P, Dahl R, Fredens K, et al. Eosinophil cationic proteins (ECP and EPX) in health and disease. In: Yoshida T, Torisu M, eds. Immunobiology of the eosinophil. Amsterdam, the Netherlands: Elsevier, 1983; 163–179 4 Wardlaw AJ. Eosinophils in the 1990’s: new perspectives on
1116
20
21
22
their role in health and disease. Postgrad Med J 1994; 70:536 –552 Gleich GJ, Flavahan NA, Fujisawa T, et al. The eosinophil as a mediator of damage to respiratory epithelium: A model for bronchial hyperreactivity. J Allergy Clin Immunol 1988; 81:776 –781 Oddera S, Silvestri M, Balbo A, et al. Airway eosinophilic inflammation, epithelial damage, and bronchial hyperresponsiveness in patients with mild-moderate, stable asthma. Allergy 1996; 51:100 –107 Takafuji S, Ohtoshi T, Takizawa H, et al. Eosinophil degranulation in the presence of bronchial epithelial cells: effect of cytokines and role of adhesion. J Immunol 1996; 156:3980 – 3985 Hallgren R, Samuelsson T, Venge P, et al. Eosinophil activation in the lung is related to lung damage in adult respiratory distress syndrome. Am Rev Respir Dis 1987; 135:639 – 642 Venge P, Henrikson J, Dahl R. Eosinophils in exerciseinduced asthma. J Allergy Clin Immunol 1991; 88: 699 –704 Tsuda H, Tsuda A, Ito M, et al. Roles of eosinophils and catecholamines in pathophysiology of exercise-induced asthma. Pediatr Allergy Immunol 1993; 4:221–215 Dufaux B, Heine O, Prinz U, et al. Effects of short maximal physical exercise on the eosinophil cationic protein. Int J Sports Med 1993; 14:468 – 470 Xu X, Hakansson L. Regulation of the release of eosinophil cationic protein by eosinophil adhesion. Clin Exp Allergy 2000; 30: 794 – 806 Weinmann GG, Bowes SM, Gerbase MW, et al. Response to acute ozone exposure in healthy man. Results of a screening procedure. Am J Respir Crit Care Med 1995; 151:33– 40 Peterson CG, Enander I, Nystrand J, et al. Radioimmunoassay of human eosinophil cationic protein (ECP) by an improved method: establishment of normal levels in serum and turnover in vivo. Clin Exp Allergy 1991; 21:561–567 Anderson SD, Smith CM. Osmotic challenge in the assessment of bronchial hyperresponsiveness. Am Rev Respir Dis 1991; 143: S43–S46 Salvi S, Semper A, Blomberg A, et al. Interleukin-5 production by human airway epithelial cells. Am J Respir Cell Mol Biol 1999; 20:984 –991 Bass DA. Reproduction of the eosinopenia of acute infection by passive transfer of a material obtained from inflammatory exudate. Infect Immun 1977; 15:410 – 416 Weber H. A quantitative study of eosinopenia and other stress indices. J Sports Med 1971; 1:12–23 Nieman DC, Berk LS, Simpson-Westerberg M, et al. Effects of long-endurance running on immune system parameters and lymphocyte function in experienced marathoners. Am J Respir Cell Mol Biol 1999; 20:984 –991 Gabriel H, Schwarz L, Born P, et al. Differential mobilization of leukocyte and lymphocyte subpopulations into the circulation during endurance exercise. Eur J Appl Physiol 1992; 65:529 –534 Sa¨ rnstrand B, Westergren-Thorsson G, Herna¨ s J, et al. Eosinophil cationic protein and transforming growth factor-A stimulates synthesis of hyaluronan and proteoglycan in human fibroblast cultures. In: Cordier LF, ed. Lyon, France: Fifth International Colloquium on Pulmonary Fibrosis, 1988; 39 Persson CGA. Eosinophil lysis and plasma extravasation. Eur Respir J 1997; 10:2438 –2439
Clinical Investigations
