Diesel exhaust exposure enhances the ozone-induced airway inflammation in healthy humans.

Exposure to particulate matter and ozone cause adverse airway reactions. Individual pollutant effects are often addressed separately, despite coexisting in ambient air. The present investigation was performed to study the effects of sequential exposures to diesel exhaust (DE) and ozone on airway inflammation in human subjects. Healthy subjects underwent bronchoscopy with bronchoalveolar lavage (BAL) and bronchial wash (BW) sampling on two occasions. Once following a DE exposure (with 300 mug.m(-3) particles with a 50% cut-off aerodynamic diameter of 10 mum) with subsequent exposure to O(3) (0.2 ppm) 5 h later. The other bronchoscopy was performed after a filtered air exposure followed by an ozone exposure, using an identical protocol. Bronchoscopy was performed 24 h after the start of the initial exposure. Significant increases in neutrophil and macrophage numbers were found in BW after DE followed by ozone exposure versus air followed by ozone exposure. DE pre-exposure also raised eosinophil protein X levels in BAL compared with air. The present study indicates additive effects of diesel exhaust on the ozone-induced airway inflammation. Together with similar results from a recent study with sequential diesel exhaust and ozone exposures, the present data stress a need to consider the interaction and cumulative effects of different air pollutants.

Bronchial mucosal dendritic cells in smokers and ex-smokers with COPD: an electron microscopic study.

BACKGROUND: Bronchial mucosal dendritic cells (DCs) initiate and regulate immune responses to inhaled antigens, viruses and bacteria. Currently, little is known of their numbers in patients with chronic obstructive pulmonary disease (COPD). While reductions in their numbers have been reported recently in smokers with asthma, nothing is known of the effects of cigarette smoking on bronchial DCs in COPD. The present study compares DC numbers in smokers and ex-smokers with COPD. METHODS: Endobronchial biopsies were obtained from 15 patients with moderate to severe COPD (10 current smokers with median forced expiratory volume in 1 s (FEV1) 45.5% predicted (range 23-68) and 5 ex-smokers with median FEV1 30% predicted (range 21-52)), 11 non-smokers with asthma (median FEV1 102% predicted (range 89-116)) and 11 non-smoker healthy controls (median FEV1 110% predicted (range 92-135)). Transmission electron microscopy (TEM) was used to identify the total population of DCs by their ultrastructure and their number in the epithelium and subepithelium was counted. RESULTS: Median (range) DC numbers were significantly lower in current smokers with COPD in the epithelium (0.0 (0.0-156.8) cells/mm2) and the subepithelium (4.5 (0.0-63.6) cells/mm2) compared with ex-smokers with COPD (97.9 (93.5-170.3) cells/mm2 in the epithelium (p<0.05); 91.8 (38.2-283.3) cells/mm2 in the subepithelium (p<0.01)). DC numbers in ex-smokers with COPD were similar to those in subjects with atopic asthma and healthy controls (131.6 (33.3-235.5) cells/mm2 in the epithelium and 64.4 (0.0-182.4) cells/mm2 in the subepithelium for the latter). CONCLUSIONS: In COPD, bronchial mucosal DC numbers are lower in current smokers while, in those who quit, numbers are similar to non-smoking subjects with asthma and non-smoking healthy controls. The functional consequences of the reduction in mucosal DC numbers in smokers with COPD have yet to be determined.

Ultrastructure of the reticular basement membrane in asthmatic adults, children and infants.

Reticular basement membrane (RBM) thickening in asthma is considered to be the result of subepithelial fibrosis. Thus, the RBM in asthma should contain an excess of fibrils identified as interstitial collagen and the ratio of fibril to matrix should be increased above normal levels. Electron micrographs of the RBM were compared with those of interstitial collagen deeper in the bronchial wall using endobronchial biopsy specimens from adult asthmatics (aged 18-41 yrs (n = 10)), children with difficult asthma (aged 6-16 yrs (n = 10)), wheezy infants with reversible airflow limitation (aged 0.3-2 yrs (n = 10)) and age-matched nonasthmatic controls: 10 adults, nine children and nine symptomatic infants with normal lung function. Fibrils in the RBM were significantly thinner (median (range) width 39 (30-52) nm versus 59 (48-73) nm), and fewer fibrils were banded than in the interstitial collagen (ratio of banded to non-banded fibrils 0.08 (0-0.17) versus 0.22 (0-1.3)). The ratio of fibrils to matrix in the thickened RBM of asthmatics did not differ from that of their respective controls (1.34 (0.63-2.49) versus 1.18 (0.31-2.6)). The ratio of fibril to matrix in the thickened reticular basement membrane of asthmatics is normal, and, contrary to what is expected in fibrosis, the fibrils do not resemble those of interstitial collagen.

Airway inflammation in iron ore miners exposed to dust and diesel exhaust.

The aim of the present study was to investigate if underground miners exposed to dust and diesel exhaust in an iron ore mine would show signs of airway inflammation as reflected in induced sputum. In total, 22 miners were studied, once after a holiday of at least 2 weeks and the second time after 3 months of regular work. Control subjects were 21 "white-collar" workers. All subjects completed a questionnaire regarding medical and occupational history, and underwent lung function testing and induced sputum collection. Total and differential cell counts and analyses of the fluid phase of the induced sputum were performed. Sampling of personal exposure to elemental carbon, nitrogen dioxide and inhalable dust was recorded. The average concentrations of inhalable dust, nitrogen dioxide and elemental carbon were 3.2 mg.m-3, 0.28 mg.m-3 and 27 microg.m-3, respectively. Miners had increased numbers of inflammatory cells, mainly alveolar macrophages and neutrophils, and increased concentrations of fibronectin, metalloproteinase-9 and interleukin-10 in induced sputum compared with controls. In conclusion, miners in an underground iron ore mine demonstrated persistent airway inflammation that was as pronounced after a 4-week holiday as after a 3-month period of work underground in the mine.

Accuracy of a first diagnosis of asthma in primary health care.

BACKGROUND: In a postal questionnaire study, the prevalence of asthma in southern Sweden has been found to be 5.5%. However, the register prevalence of asthma obtained from the medical records in the same municipality and age groups was found to be only 2.1%. OBJECTIVES: The aims of the study were to investigate whether the low register prevalence of asthma was caused by an underdiagnosis of asthma in primary health care and to validate a first diagnosis of asthma set by GPs in primary health care. METHODS: During a period of 3 months in 1997, all patients seeking care in the primary health care units of the municipality of Lund (population 171 877) with upper or lower airway infections, prolonged cough, allergic rhinitis, fatigue or a first positive diagnosis of asthma were recorded ( n = 3025). RESULTS: In the whole group of 3025 patients, 99 patients were found to have received a diagnosis of asthma for the first time during the study period. The diagnosis was verified in 52 of those 68 patients who attended a follow-up and examination by a respiratory physician. Among the remaining 2926 patients, 221 patients were selected randomly to constitute a control group. In this group, three patients were found to have asthma. Thus, the specificity of an asthma diagnosis set in primary health care was 0.99 [95% confidence interval (CI) 0.99-1.00] and the sensitivity was 0.59 (95% CI 0.31-0.81). CONCLUSIONS: The GPs in this study were good at excluding those who did not have asthma (specificity 99%) but less good in correctly diagnosing those who actually had current asthma (sensitivity 59%), which suggests an underdiagnosis of asthma.

Diesel exhaust enhances airway responsiveness in asthmatic subjects.

Particulate matter (PM) pollution has been associated with negative health effects, including exacerbations of asthma following exposure to PM peaks. The aim of the present study was to investigate the effects of short-term exposure to diesel exhaust (DE) in asthmatics, by specifically addressing the effects on airway hyperresponsiveness, lung function and airway inflammation. Fourteen nonsmoking, atopic asthmatics with stable disease, on continuous treatment with inhaled corticosteroids, were included. All were hyperresponsive to methacholine. Each subject was exposed to DE (particles with a 50% cut-off aerodynamic diameter of 10 microm (PM10) 300 microg x m(-3)) and air during 1 h on two separate occasions. Lung function was measured before and immediately after the exposures. Sputum induction was performed 6 h, and methacholine inhalation test 24 h, after each exposure. Exposure to DE was associated with a significant increase in the degree of hyperresponsiveness, as compared to after air, of 0.97 doubling concentrations at 24 h after exposure (p < 0.001). DE also induced a significant increase in airway resistance (p=0.004) and in sputum levels of interleukin (IL)-6 (p=0.048). No changes were detected in sputum levels of methyl-histamine, eosinophil cationic protein, myeloperoxidase and IL-8. This study indicated that short-term exposure to diesel exhaust, equal to high ambient levels of particulate matter, is associated with adverse effects in asthmatic airways, even in the presence of inhaled corticosteroid therapy. The increase in airway responsiveness may provide an important link to epidemiological findings of exacerbations of asthma following exposure to particulate matter.

Prevalence of nasal symptoms and their relation to self-reported asthma and chronic bronchitis/emphysema.

Little information is available on associations between rhinitis and chronic bronchitis/emphysema (CBE). Self-reported upper airway symptoms, asthma, and CBE were examined in 12,079 adults living in southern Sweden. The response rate was 70% (n=8,469), of whom 33% reported significant nasal symptoms: a blocked nose was reported by 21%; sneezing by 18%; nasal discharge by 17%; and thick yellow nasal discharge by 5.7%. Nasal symptoms and combined nasal and self-reported bronchial disease were generally more common among smokers than nonsmokers. There was little overlap between asthma and CBE, but 46% of those with asthma and 40% of those with CBE had significant nasal symptoms. Best predicting factors (odds ratios >3) for asthma and CBE were nasal symptoms due to exposure to animals and damp/cold air, respectively. One-third of an adult, southern Swedish population, had significant allergic and/or nonallergic nasal symptoms. Nasal symptoms were frequently found to coexist with both asthma and chronic bronchitis/emphysema, suggesting that pan-airway engagement is common in both diseases. Differing associations between types of nasal symptoms and allergic and irritant triggers of nasal symptoms, with regard to asthma and chronic bronchitis/emphysema, emphasize the different natures of these bronchial diseases.

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.

Recombinant humanized mAb-E25, an anti-IgE mAb, in birch pollen-induced seasonal allergic rhinitis.

BACKGROUND: Allergic rhinitis is a common condition often requiring treatment. OBJECTIVE: We evaluated whether recombinant humanized (rhu)mAb-E25, a recombinant humanized construct of a murine antibody that binds to circulating IgE, could control symptoms and reduce intake of concomitant medication in seasonal allergic rhinitis (SAR) induced by birch pollen if given subcutaneously in a dose schedule predicted to reduce serum free IgE levels below 25 ng/mL. METHODS: We randomly assigned 251 adult subjects with a history of SAR and a positive skin test response to birch pollen to receive 300 mg of rhumAb-E25 or placebo given 2 or 3 times during the season, depending on baseline IgE levels. The primary efficacy variable was the subject's average daily nasal symptom severity score (sneezing, itching, runny, and stuffy nose) from diary data collected over the double-blind treatment period. Secondary efficacy variables included the average number of rescue antihistamine tablets per day, the proportion of days with any SAR medication use, and rhinoconjunctivitis-specific quality of life (QOL). RESULTS: Significant between-treatment differences in favor of rhumAb-E25 were observed in average daily nasal symptom severity scores, the average number of tablets of rescue antihistamines per day, the proportion of days with any SAR medication use, and all domains of QOL. Serum-free IgE levels were markedly lower in rhumAb-E25-treated subjects and were associated with clinical effectiveness. Recombinant humanized mAb-E25 was well tolerated. No anti-rhumAb-E25 antibodies were detected. CONCLUSION: Compared with placebo, rhumAb-E25 was safe and effective in controlling birch pollen-induced SAR symptoms, with less concomitant medication use and improved QOL. This study shows the therapeutic potential of anti-IgE antibody in SAR.

Airway inflammation following exposure to diesel exhaust: a study of time kinetics using induced sputum.

The adverse health effects of particulate matter pollution are of increasing concern. In a recent bronchoscopic study in healthy volunteers, pronounced airway inflammation was detected following exposure to diesel exhaust (DE). The present study was conducted in order to evaluate the time kinetics of the inflammatory response following exposure to DE using induced sputum from healthy volunteers. Fifteen healthy nonsmoking volunteers were exposed to DE particles with a 50% cut-off aerodynamic diameter of 10 microm 300 microg x m(-3) and air for 1 h on two separate occasions. Sputum induction with hypertonic saline was performed 6 and 24 h after each exposure. Analyses of sputum differential cell counts and soluble protein concentrations were performed. Six hours after exposure to DE, a significant increase was found in the percentage of sputum neutrophils (37.7 versus 26.2% p=0.002) together with increases in the concentrations of interleukin-6 (12.0 versus 6.3 pg x mL(-1), p=0.006) and methylhistamine (0.11 versus 0.12 microg x L(-1), p=0.024). Irrespective of exposure, a significant increase was found in the percentage of sputum neutrophils at 24 as compared to 6 h, indicating that the procedure of sputum induction itself may change the composition of sputum. This study demonstrates that exposure to diesel exhaust induces inflammatory response in healthy human airways, represented by an early increase in interleukin-6 and methylhistamine concentration and the percentage of neutrophils. Induced sputum provides a safe tool for the investigation of the inflammatory effects of diesel exhaust, but care must be taken when interpreting results from repeated sputum inductions.

Familial related risk-factors in the development of chronic bronchitis/emphysema as compared to asthma assessed in a postal survey.

There is a lack of knowledge to which extent heredity or familial risk factors are involved in the development of chronic bronchitis/emphysema (CBE). Smoking is regarded as the most important risk factor, but only about 15% of smokers develop airway obstruction. We evaluated the importance of familial risk factors compared to smoking and ex-smoking using an epidemiological approach. In 1992, a postal questionnaire was distributed to a study sample. In all, 43 questions were asked, in a previously evaluated questionnaire, regarding respiratory symptoms, self-reported lung diseases, smoking habits and familial occurrence of chronic bronchitis and asthma. The questionnaire was sent to 12,073 adults living in the southernmost part of Sweden. The age range was 20-59 years with an equal gender distribution. The study sample was drawn from the population records. The questionnaire was answered by 8469 subjects (70.1%), of whom 392 subjects (4.6%) stated that they had or had had CBE and 469 subjects (5.5%) stated that they had or had had asthma. In a model with logistic regression using the five explanatory variables gender, age, familial occurrence for asthma, familial occurrence for CBE and current or ex-smoking the most important risk factors for CBE were familial occurrence for chronic bronchitis [Odds ratios (OR): 5.19, 95% confidence interval (CI): 4.09-6.60, p = 0.000] and current or ex-smoking (OR: 1.74, 95% CI: 1.41-2.14, p = 0.000). The most important risk factors for asthma were familial occurrence for asthma (OR: 3.71, 95% CI: 3.06-4.51, p = 0.000) and current or ex-smoking (OR: 1.33, 95% CI: 1.09-1.61, p = 0.004). We have found that familial occurrence for CBE in first degree relatives together with smoking is a stronger risk factor for the development of CBE than is smoking.

How to measure airway inflammation: bronchoalveolar lavage and airway biopsies.

Airway inflammation is a characteristic feature of asthma. Bronchoscopy with bronchoalveolar lavage (BAL) and/or mucosal airway biopsies has provided invaluable information about the nature of asthmatic inflammation. A common finding in all BAL studies in asthma is increased numbers or proportions of eosinophils even in subjects with mild disease. BAL cells in asthmatics demonstrate a cytokine profile consistent with a T helper2-like phenotype, with increased expression of interleukin (IL)-4 and IL-5. Endobronchial mucosal biopsies show loss of surface epithelium, thickening of the reticular layer of the basement membrane and an increased cellular infiltrate of mainly eosinophils, mast cells and T lymphocytes, and up-regulation of a number of cytokines. Recently, peripheral airways from asthmatics have been investigated, and even more intense inflammation has been described. However, in severe steroid-dependent asthmatics, intriguing differences in the type of inflammation have been described. The term 'airway remodelling' indicates structural changes seen in long standing asthma, where myofibroblasts might be of particular importance. BAL and mucosal biopsies are important tools in the investigation of airway inflammation in asthma.

Prevalence of obstructive lung diseases and respiratory symptoms in southern Sweden.

The prevalence of obstructive lung diseases is increasing in Scandinavia and worldwide. The reasons for this are not known. The prevalence varies between countries but also between different areas within the same country. In northern Europe a north-south gradient and also an east-west gradient have been proposed. To our knowledge this is the first comprehensive epidemiological study concerning obstructive lung diseases and respiratory symptoms in the southern part of Sweden. The prevalence of bronchial asthma, chronic bronchitis/emphysema, respiratory symptoms, smoking habits and medication in a random sample of 12,071 adults aged 20-59 years was assessed in a postal survey with a slightly modified questionnaire previously used in central and northern Sweden (the OLIN Studies). The questionnaire was based on the British Medical Research Council (BMRC) questionnaire. We also compared the prevalence figures of asthma found in the postal survey with those reported in the medical records in a part of the study area. After two reminders, the response rate was 70.1% (n = 8469); 33.8% of the responders were smokers. Among younger (20-39 year age group) individuals, smoking was most common in women, whereas in those aged 40-59 years, smoking was more common in men. In all, 469 subjects (5.5%) stated that they had asthma, 41.6% of whom reported a family history of asthma compared to 15.9% of the study sample not reporting asthma. Of all subjects reporting asthma, 60.1% (n = 282) answered that they used asthma drugs. Inhaled steroids were used by 20.7%. Chronic bronchitis and/or emphysema was reported by 4.6% (n = 392), 28.6% of whom reported a family history of chronic bronchitis or emphysema compared to 6.8% of the study sample not reporting chronic bronchitis. The most common respiratory symptom in the study population was 'phlegm when coughing' reported by 15.1% (n = 1279). Our data show a prevalence of self-reported asthma of 5.5% compared with 7% reported by Lunbäck et al. in northern Sweden, which indicates a north-south gradient.

Myofibroblast involvement in the allergen-induced late response in mild atopic asthma.

We undertook a detailed cellular and ultrastructural examination of bronchial biopsies from seven allergic asthmatic patients and 10 nonasthmatic control subjects (five atopic and five nonatopic) to determine the nature of the inflammation that occurs during allergen-induced late-phase responses (LPRs). The asthmatic subjects had mild asthma (FEV1 = 94 +/- 9% predicted; mean +/- SEM) and required only intermittent use of beta 2-agonists. Airway mucosal biopsy specimens were obtained on a single occasion from the nonasthmatic controls and on two occasions from the asthmatic subjects, at 24 h after diluent challenge and 24 h after challenge with allergen 3 wk later. The mean maximal decrease in FEV1 during the late response after allergen challenge was 30%, and that after administration of diluent was 4%. In coded plastic sections, subepithelial cells were counted with both light and electron microscopy, and the numbers present were expressed per 0.1 mm2 of tissue. Light microscopy revealed statistically significant increases in the total number of inflammatory cells (P < 0.02) and in "activated fibroblasts" after allergen challenge (P < 0.05). Electron microscopy showed significant increases after allergen challenge in the total number of eosinophils (P < 0.05) and cells with the ultrastructural features of myofibroblasts. The latter cells constituted 1.5% of cells after administration of diluent, and this increased to 15.5% after allergen challenge (P < 0.05). Mast cells were significantly more abundant in the atopic nonasthmatic controls than in the asthmatic subjects after allergen challenge. The study demonstrates that the profile of inflammatory cells in asthma at 24 h after allergen challenge is distinct from that in stable asthma and in nonasthmatic controls, and that migratory cells with a contractile phenotype appear in greater numbers in the late response. We propose that subjects who repeatedly develop a late response have increased numbers of migrating, contractile cells that may contribute to formation of the increased bronchial smooth-muscle mass observed in fatal asthma.

Prolonged protection against exercise-induced bronchoconstriction by the leukotriene D4-receptor antagonist cinalukast.

OBJECTIVES: The degree and duration of protection against exercise-induced bronchoconstriction afforded by three doses of a specific leukotriene D4 receptor antagonist, cinalukast, were assessed after an initial dosing and after 1 week of therapy. METHODS: A placebo-controlled crossover study was performed in eight male patients who had mild, stable asthma and exercise-induced bronchoconstriction. Treatment consisted of four 7-day periods of placebo and three dose levels of the drug (10, 50, and 200 mg administered orally). Exercise challenge was performed at 2 hours and 8 hours after treatment on the first and seventh treatment days. The response was measured as the area under the FEV1-time effect curve (AUEC). RESULTS: On the first day of treatment, the mean (+/- SEM) AUEC at 2 hours was 24.2 +/- 3.3 L.min after placebo and was 5.5 +/- 2.2 L.min, 6.3 +/- 2.7 L.min, 3.3 +/- 3.8 L.min after 10 mg, 50 mg, and 200 mg, respectively (p < 0.05 for all values compared with placebo). The AUEC at 8 hours on the first day was 25.1 +/- 4.4 L.min after placebo and was 6.8 +/- 4.1 L.min, 11.2 +/- 2.5 L.min, and 5.0 +/- 2.8 L.min after 10 mg, 50 mg, and 200 mg, respectively (p < 0.05 for all values compared with placebo). The protection afforded by 10 mg of cinaluicast was lost after 7 days of treatment but persisted with 50 mg and 200 mg doses. CONCLUSION: Orally administered cinalukast provides at least 8 hours of protection against exercise-induced bronchoconstriction. This protection is lost with regular treatment for 1 week for the lowest dose studied.

Interleukin-3 in bronchial biopsies from nonasthmatics and patients with mild and allergen-induced asthma.

Cytokines, such as interleukin-3 (IL-3), have been suggested to play an important role in mediating the increased number of airway eosinophils and metachromatic cells in patients with even mild asthma. We used immunohistochemistry to determine the presence of IL-3 protein in bronchial biopsies from nonasthmatics (n = 10) and subjects with mild (n = 8) and allergen-induced (n = 7) asthma. We also examined whether IL-3 was related to airway eosinophil number and activation, the number of airway metachromatic cells, or airway function. We found that the number and activation of eosinophils and the number of metachromatic cells were increased in the airways of asthmatics, compared with nonasthmatics, with further increases evident after allergen challenge. IL-3 protein was localized primarily to the epithelium in nonasthmatic and asthmatic subjects, with no difference apparent between groups or after allergen inhalation challenge. The extent of staining for IL-3 in the tissue was not correlated with eosinophil number or activity, metachromatic cell number, airway responsiveness, or the severity of the late asthmatic response. This study provides the first demonstration of IL-3 protein localization in bronchial tissue from human airways. The results suggest that the increases in eosinophils and metachromatic cells associated with mild and allergen-induced asthma occur independent of IL-3.

The effects of an inhaled corticosteroid on oxygen radical production by bronchoalveolar cells after allergen or ozone in dogs.

Both ozone and allergen inhalation increase the capacity to produce oxygen radicals by bronchoalveolar lavage cells in dogs. The purpose of these studies was to determine whether inhaled corticosteroids inhibits these increases in oxygen radical production from bronchoalveolar lavage cells. Six random source dogs were studied after dry air or ozone inhalation (3 ppm, 30 min). Seven random source dogs were studied after diluent or allergen inhalation. The dogs inhaled budesonide (2.74 mg/day) or lactose powder, twice daily for 7 days before ozone and allergen. 90 min after ozone or dry air, and 24 h after Ascaris suum or diluent a bronchoalveolar lavage was carried out. Spontaneous luminol-enhanced chemiluminescence was measured from bronchoalveolar lavage cells (4 x 10(6) cells) for 10 min, followed by a measurement of phorbol myristate acetate (PMA 2.4 micromol/l) stimulated chemiluminescence for 10 min. Both ozone and allergen inhalation caused an increase in PMA stimulated chemiluminescence (P<0.05). Budesonide pretreatment inhibited ozone-induced (P<0.008), but not allergen-induced PMA stimulated chemiluminescence (P>0.90). Both ozone and allergen inhalation caused an increase in the bronchoalveolar lavage neutrophils. Budesonide pretreatment significantly inhibited the ozone-induced (P=0.007), but not the ascaris-induced neutrophil influx (P=0.93). These results demonstrate that ozone, but not allergen, stimulated oxygen radical release and neutrophil influx are attenuated by inhaled corticosteroids. This suggests that luminol-enhanced chemiluminescence from bronchoalveolar lavage cells measures oxygen radicals derived from neutrophils, and that ozone-and allergen-induced bronchoalveolar lavage neutrophilia are caused by different mechanisms.