Interleukin-33 amplifies IgE synthesis and triggers mast cell degranulation via interleukin-4 in naïve mice

Background

The regulation and function of IgE in healthy individuals and in antigen-naïve animals is not well understood. IL-33 administration increases serum IgE in mice with unknown mechanism. We tested the hypothesis that IL-33 provides an antigen-independent stimulus for IgE production and mast cell degranulation.

Methods

IL-33 was administered to naïve wild-type (WT), nude and ST2^−/−, IL-4^−/−, IL4Rα^−/− and T-or B-cell-specific IL-4Rα^−/− mice. IgEand cytokines were quantified by ELISA. T- and B-lymphocyte numbers and CD40L expression were determined by flow cytometry. Anaphylaxis was measured by temperature, mast cell degranulation and histamine release.

Results

IL-33 enhanced IgE production in naïve WT, T-IL-4Rα^−/− but not in ST2^−/−, IL-4^−/−, IL-4Rα^−/− or B-cell-specific IL-4Rα^−/− mice, demonstrating IL-33 specificity and IL-4 dependency. Moreover, IL-4 was required for IL-33-induced B-cell proliferation and T-cell CD40L expression, which promotes IgE production. IL-33-induced IL-4 production was mainly from innate cells including mast cells and eosinophils. IL-33 increased mast cell surface IgE and triggered degranulation and systemic anaphylaxis in allergen-naïve WT but not in IL-4Rα^−/− mice.

Conclusion

IL-33 amplifies IgE synthesis and triggers anaphylaxis in naïve mice via IL-4, independent of allergen. IL-33 may play an important role in nonatopic allergy and idiopathic anaphylaxis.

Genome-wide association study to identify genetic determinants of severe asthma

BACKGROUND

The genetic basis for developing asthma has been extensively studied. However, association studies to date have mostly focused on mild to moderate disease and genetic risk factors for severe asthma remain unclear.

OBJECTIVE

To identify common genetic variants affecting susceptibility to severe asthma.

METHODS

A genome-wide association study was undertaken in 933 European ancestry individuals with severe asthma based on Global Initiative for Asthma (GINA) criteria 3 or above and 3346 clean controls. After standard quality control measures, the association of 480 889 genotyped single nucleotide polymorphisms (SNPs) was tested. To improve the resolution of the association signals identified, non-genotyped SNPs were imputed in these regions using a dense reference panel of SNP genotypes from the 1000 Genomes Project. Then replication of SNPs of interest was undertaken in a further 231 cases and 1345 controls and a meta-analysis was performed to combine the results across studies.

RESULTS

An association was confirmed in subjects with severe asthma of loci previously identified for association with mild to moderate asthma. The strongest evidence was seen for the ORMDL3/GSDMB locus on chromosome 17q12-21 (rs4794820, p=1.03×10((-8)) following meta-analysis) meeting genome-wide significance. Strong evidence was also found for the IL1RL1/IL18R1 locus on 2q12 (rs9807989, p=5.59×10((-8)) following meta-analysis) just below this threshold. No novel loci for susceptibility to severe asthma met strict criteria for genome-wide significance.

CONCLUSIONS

The largest genome-wide association study of severe asthma to date was carried out and strong evidence found for the association of two previously identified asthma susceptibility loci in patients with severe disease. A number of novel regions with suggestive evidence were also identified warranting further study.

Variance as a signature of neural computations during decision making

Traditionally, insights into neural computation have been furnished by averaged firing rates from many stimulus repetitions or trials. We pursue an analysis of neural response variance to unveil neural computations that cannot be discerned from measures of average firing rate. We analyzed single-neuron recordings from the lateral intraparietal area (LIP), during a perceptual decision-making task. Spike count variance was divided into two components using the law of total variance for doubly stochastic processes: (1) variance of counts that would be produced by a stochastic point process with a given rate, and loosely (2) the variance of the rates that would produce those counts (i.e., "conditional expectation"). The variance and correlation of the conditional expectation exposed several neural mechanisms: mixtures of firing rate states preceding the decision, accumulation of stochastic "evidence" during decision formation, and a stereotyped response at decision end. These analyses help to differentiate among several alternative decision-making models.

Peripheral blood dendritic cell subtypes are significantly elevated in subjects with asthma

BACKGROUND

Dendritic cells (DCs) are crucial for the processing of antigens, T lymphocyte priming and the development of asthma and allergy. Smokers with asthma display altered therapeutic behaviour and a reduction in endobronchial DC CD83 expression compared with non-smokers with asthma. No information is available on the impact of smoking on peripheral blood DC profiles.

OBJECTIVE

Determine peripheral blood DC profiles in subjects with and without asthma with differing smoking histories.

METHODS

Forty-three asthmatics (17 smokers, nine ex-smokers and 17 never-smokers) and 16 healthy volunteers (nine smokers and seven never-smokers) were recruited. Spirometry, exhaled nitric oxide and venesection was performed. DC elution was by flow cytometry via the expression of DC surface markers [plasmacytoid (pDC) (BDCA-2, CD303), type 1 conventional (cDC) (BDCA-1, CD1c), and type 2 cDC (BDCA-3, CD141)].

RESULTS

Subjects with asthma displayed increases in all DC subtypes compared with normal never-smokers: [type 1 cDCs - asthma [median% (IQR)]: 0.59% (0.41, 0.74), normal never-smokers: 0.35% (0.26, 0.43), P=0.013]; type 2 cDCs - asthma: 0.04% (0.02, 0.06), normal never-smokers: 0.02% (0.01, 0.03), P=0.008 and pDCs - asthma: 0.32% (0.27, 0.46), normal never-smokers: 0.22% (0.17, 0.31), P=0.043, and increased pDC and type 1 cDCs compared with normal smokers. Smoking did not affect DC proportions in asthma. Cigarette smoking reduced pDC proportions in normal subjects [normal never-smokers: 0.22% (0.17, 0.31); normal smokers: 0.09% (0.08, 0.15), P=0.003].

CONCLUSIONS AND CLINICAL RELEVANCE

This study shows for the first time that subjects with asthma display a large increase in peripheral blood DC proportions. Cigarette smoking in asthma did not affect the peripheral blood DC profile but did suppress pDC proportions in non-asthmatic subjects. Asthma is associated with a significant increase in circulating DCs, reflecting increased endobronchial levels and the importance of DCs to the development and maintenance of asthma. (Clinical trials.gov identifier: NCT00411320)

Effect of improved home ventilation on asthma control and house dust mite allergen levels

BACKGROUND

The warm, humid environment in modern homes favours the dust mite population, but the effect of improved home ventilation on asthma control has not been established. We tested the hypothesis that a domestic mechanical heat recovery ventilation system (MHRV), in addition to allergen avoidance measures, can improve asthma control by attenuating re-colonization rates.

METHODS

We conducted a randomized double-blind placebo-controlled parallel group trial of the installation of MHRV activated in half the homes of 120 adults with asthma, allergic to Dermatophagoides pteronyssinus. All homes had carpets steam cleaned and new bedding and mattress covers at baseline. The primary outcome was morning peak expiratory flow (PEF) at 12 months.

RESULTS

At 12 months, the primary end-point; change in mean morning PEF as compared with baseline, did not differ between the MHRV group and the control group (mean difference 13.5 l/min, 95% CI: -2.6 to 29.8, P = 0.10). However, a secondary end-point; evening mean PEF, was significantly improved in the MHRV group (mean difference 24.5 l/min, 95% CI: 8.9-40.1, P = 0.002). Indoor relative humidity was reduced in MHRV homes, but there was no difference between the groups in Der p 1 levels, compared with baseline.

CONCLUSIONS

The addition of MHRV to house dust mite eradication strategies did not achieve a reduction in mite allergen levels, but did improve evening PEF.

Effect of low-dose theophylline plus beclometasone on lung function in smokers with asthma: a pilot study

Smoking is common in asthma and is associated with worse asthma control and a reduced therapeutic response to corticosteroids. The present authors hypothesised that treating smokers with asthma with low-dose theophylline added to inhaled corticosteroids would enhance steroid sensitivity and thereby improve lung function and symptoms. In a double-blind, parallel group exploratory trial, 68 asthmatic smokers were randomised to one of three treatments for 4 weeks: inhaled beclometasone (200 microg day(-1)), theophylline (400 mg day(-1)) or both treatments combined. Outcome measures included change in lung function and Asthma Control Questionnaire (ACQ) scores. At 4 weeks, theophylline added to inhaled beclometasone produced an improvement in peak expiratory flow (39.9 L min(-1), 95% confidence intervals (CI) 10.9-68.8) and ACQ score (-0.47, 95% CI -0.91- -0.04) and a borderline improvement in pre-bronchodilator forced expiratory volume in one second (mean difference 165 mL, 95% CI -13-342) relative to inhaled corticosteroid alone. Theophylline alone improved the ACQ score (-0.55, 95% CI -0.99- -0.11), but not lung function. In the present pilot study, the combination of low-dose theophylline and inhaled beclometasone produced improvements in both lung function and symptoms in a group of smokers with asthma. Larger trials are required to extend and confirm these findings.

Role of bilirubin as antioxidant in neonatal jaundice and effect of ethanolic extract of sweet lime peel on experimentally induced jaundice in rat

Bilirubin above a threshold level is toxic to human system and is excreted in urinary and through gastrointestinal tract. The role of bilirubin as antioxidant is debatable. This paper aims at elucidating the role of bilirubin as an antioxidant in neonatal jaundice patients. It is observed that bilirubin up to 6 mg/dl in blood acts as an antioxidant and above 12.5 mg/dl is strongly prooxidant. Phototherapy is the accepted therapeutic management of neonatal jaundice and has been shown to enhance the oxidative stress. Approaches have been taken to formulate a herbal medication which will reduce bilirubin level in the neonates without inducing additional damages. The ethanolic extract of sweet lime peel, administered orally at a dose of 72 microg is found to reduce the oxidative stress in erythrocytes of phenylhydrazine-induced jaundiced rats treated with phototherapy.

Perspectives on advancing preventative medicine through vaccinology at the comparative veterinary, human and conservation medicine interface: not missing the opportunities

Vaccination has historically and remains one of the most cost-effective and safest forms of medicine today. Along with basic understanding of germ theory and sanitation, vaccination, over the past 50 years, has transformed lives and economies in both rich and poor countries by its direct impact on human and animal life--resulting in the eradication of small pox, huge reductions in the burden of previously common human and animal diseases such as polio, typhoid, measles in human medicine and contagious bovine pleuropneumonia, foot-and-mouth disease, screwworm and hog cholera and the verge of eradicating brucellosis, tuberculosis, and pseudorabies in veterinary medicine. In addition vaccination along with other animal production changes has provided the ability to produce otherwise unaffordable animal protein and animal health worldwide. The landscape however on which vaccinology was discovered and applied over the past 200 years, even in the past 10 years has and is undergoing continuous change. For vaccination as a public health tool to have its greatest impacts in human and veterinary medicine, these great medical sciences will have to come together, policy-relevant science for sustainable conservation in developing and developed countries needs to become the norm and address poverty (including lack of basic health care) in communities affected by conservation, and to consider costs and benefits (perceived or not) affecting the well-being of all stakeholders, from the local to the multinational. The need to return to and/or develop new education-based models for turning the tide from the heavily return-on-investment therapeutic era of the last century into one where the investment into the preventative sciences and medicine lead to sustainable cultural and cost-effective public health and economic changes of the future is never more evident than today. The new complex problems of the new millennium will require new educational models that train para- and professional people for thinking and solving complex inter-related biological, ecological, public-, political/economic problems. The single profession that is best positioned to impact vaccinology is Veterinary Medicine. It's melding with human medicine and their role in future comparative and conservation-based programs will be critical to the successful application of vaccines into the 21st century.

Effects of atorvastatin added to inhaled corticosteroids on lung function and sputum cell counts in atopic asthma

BACKGROUND

Statins have anti-inflammatory properties that may be beneficial in the treatment of asthma. A study was undertaken to test the hypothesis that atorvastatin added to inhaled corticosteroids improves lung function and airway inflammation in atopic adults with asthma.

METHODS

54 adults with atopic asthma were recruited to a double-blind randomised controlled crossover trial comparing the effect of oral atorvastatin 40 mg daily with that of a matched placebo on asthma control and airway inflammation. Each treatment was administered for 8 weeks separated by a 6-week washout period. The primary outcome was morning peak expiratory flow (PEF). Secondary outcomes included forced expiratory volume in 1 s, asthma control questionnaire score, airway hyper-responsiveness to methacholine, induced sputum cytology and inflammatory biomarkers.

RESULTS

At 8 weeks the change in mean morning PEF compared with baseline did not differ substantially between the atorvastatin and placebo treatment periods (mean difference -0.5 l/min, 95% CI -10.6 to 9.6, p = 0.921). Values for other clinical outcomes were similar between the atorvastatin and placebo treatment periods. The absolute sputum macrophage count was reduced after atorvastatin compared with placebo (mean difference -45.0 x 10(4) cells, 95% CI -80.1 to -9.7, p = 0.029), as was the sputum fluid leucotriene B4 (mean difference -88.1 pg/ml, 95% CI -156.4 to -19.9, p = 0.014).

CONCLUSION

The addition of atorvastatin to inhaled corticosteroids results in no short-term improvement in asthma control but reduces sputum macrophage counts in mild to moderate atopic asthma. The change in sputum macrophage count suggests potential areas for investigation of statins in other chronic lung diseases.

Role of symptoms and lung function in determining asthma control in smokers with asthma

BACKGROUND

Cigarette smoking in asthma increases the severity and accelerates the decline in lung function. The relative role of symptoms and lung function in determining asthma control in smokers with asthma is not known.

AIM OF THE STUDY

The aim of this study was to compare asthma control in smokers vs never-smokers with asthma, using the validated Juniper asthma control questionnaire (ACQ), and assess if any difference was because of a particular symptom or the forced expiratory volume in one second (FEV(1)) value.

METHODS

This was a cross-sectional study of 134 asthmatics (74 never-smokers and 60 smokers) with >or=15% reversibility in FEV(1) after salbutamol. All subjects completed the ACQ, recording FEV(1) and asthma symptoms (night awakening, morning symptoms, dyspnoea, wheeze, activity limitation and use of reliever inhaler).

RESULTS

Compared with the never-smokers, smokers with asthma had significantly worse median (IQR) total asthma control score [1.6 (1.1-2.3) vs 2.8 (1.7-3.4); (P < 0.0001)] and in each of the six individual symptom question scores (P < 0.001), but no difference in FEV(1) levels (P = 0.908).

CONCLUSION

Asthma control is significantly worse in asthmatics who smoke compared with never-smokers, with all symptoms related to asthma control uniformly worse in smokers, independent of FEV(1).

Systemic sensitivity to corticosteroids in smokers with asthma

Cigarette smokers with asthma are insensitive to the therapeutic effects of corticosteroids. It is not known whether this insensitivity to corticosteroids in smokers affects tissue sites beyond the airways. A total of 75 asthmatic subjects (39 smokers) and 78 healthy controls (30 smokers) were recruited to an observational study. The cutaneous and peripheral blood lymphocyte responses to corticosteroids were measured. The cutaneous vasoconstrictor response to topical beclometasone was measured by applying different concentrations of beclometasone solutions to the skin in a random double-blind manner. The degree of blanching at each concentration was graded after 18 h. The sensitivity of peripheral blood lymphocytes to corticosteroids was assessed by measuring the suppressive effect of dexamethasone on lymphocyte proliferation stimulated by phytohaemagglutinin (PHA). Total mean+/-sd cutaneous vasoconstrictor response score to beclometasone was reduced in smokers with asthma to 5.39+/-3.58 versus 7.26+/-3.05 in never-smokers with asthma; and in all smokers to 6.47+/-3.33 versus 7.86+/-2.81 in all never-smokers. The sensitivity to corticosteroids of lymphocytes stimulated by PHA was similar between groups. In conclusion, smokers with asthma have an impaired cutaneous vasoconstrictor response to topical corticosteroids compared with never-smokers with asthma. This finding suggests that the insensitivity to corticosteroids in smokers with asthma affects tissue sites other than the airways.

The radiological appearances of thalassaemia

The skeletal changes of untreated thalassaemia result from ineffective erythropoiesis and expansion of the bone marrow and affect every part of the skeleton. These changes include osteoporosis, growth retardation, platyspondyly and kyphosis. Erythropoiesis occurs at extra-medullary sites, most commonly resulting in a paraspinal mass but occasionally affecting organs containing pluripotential stem cells. Repeated transfusion unaccompanied by iron chelation causes haemosiderosis; iron is deposited at various sites causing functional impairment. Iron-chelation therapy with desferrioxamine (DFX) prevents haemosiderosis but causes a skeletal dysplasia predominantly affecting the rapidly growing long bones, in particular the distal ulna, and causing irregularity and sclerosis of the physeal-metaphyseal junction and splaying of the metaphysis. DFX also exacerbates the observed growth retardation. DFX-induced skeletal dysplasia may herald toxicity, which is associated with visual and auditory impairment. Therefore, careful balancing of the transfusion regimen and iron-chelation therapy is required. Magnetic resonance imaging (MRI) is the most sensitive technique for the detection of DFX-induced dysplasia.

Serum and sputum neurotrophin levels in chronic persistent cough

BACKGROUND

Neurotrophins (NTs) are a family of growth factors, including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and neurotrophin3 (NT-3) that are involved in inflammation. Serum and induced sputum NT levels are increased in asthma and in cough because of idiopathic pulmonary fibrosis, respectively. Neurogenic inflammation is implicated in the pathogenesis of chronic cough in individuals with normal chest radiography, but the role of NTs in this condition is unknown.

OBJECTIVE

To assess if NT levels are elevated in the serum and airways in subjects with chronic persistent cough.

METHODS

Eighty-one subjects with chronic cough persistent for over 1 year; with normal chest radiography and spirometry were included. Thirty healthy subjects were controls. Serum NGF, BDNF and NT-3 were measured by enzyme immunoassay. In a subset, NGF was measured in induced sputum. Sputum cell counts and allergen-specific serum IgE were measured and all patients received specific sequential treatment trials to achieve a final diagnosis for the cough.

RESULTS

There was no significant difference either in the levels of serum or sputum NTs in chronic cough subjects compared with controls or between the most common causes of cough: post-nasal drip syndrome, gastro-oesophageal reflux disease, asthma and bronchiectasis. The median (inter-quartile range) for sputum NGF (pg/mL) was 516 (296-772) in healthy controls and 580 (312-880) in subjects with chronic cough (P=0.284). There was no correlation between NT levels and sputum cell counts. Sputum NGF levels correlated with duration of cough (r=0.34, P=0.002).

CONCLUSION

NTs are not elevated in induced sputum or serum of subjects with chronic persistent cough. This implies that NTs do not have a central role in perpetuating airway inflammation in chronic persistent cough.

Occupational injuries: is job security a factor?

CONTEXT

Although a large number of contributing factors of occupational injury causation are explored meticulously to explain the phenomenon of higher occupational injury occurrence in some subjects, it has remained a matter of controversy.

AIMS

In this study, an effort is made to explore whether job security has any contribution in explaining higher susceptibility of some workers.

SETTINGS AND DESIGN

This was a retrospective occupational injury record study conducted in an industry of eastern India.

MATERIALS AND METHODS

Along with the study of injury records of 5 years, an interview was also conducted involving 726 workers (including permanent and temporary workers both) of the factory.

STATISTICAL ANALYSIS USED

Comparison was made between permanent and temporary workers by using the Mann-Whitney U-test and the chi-square test. A theoretical model of Poisson's distribution was used to compare between expected and real occurrence.

RESULTS

Although two worker groups were very similar in relation to age, level of education, habits, and nature of work, accident frequency and severity rates were found to be significantly higher in temporary workers.

CONCLUSIONS

This study concluded that the higher accident risk of the temporary workers might have been due to the less effective experience as well as due to lack of job security inherent in such workers.

Occupational injuries: is job security a factor?

CONTEXT

Although a large number of contributing factors of occupational injury causation are explored meticulously to explain the phenomenon of higher occupational injury occurrence in some subjects, it has remained a matter of controversy.

AIMS

In this study, an effort is made to explore whether job security has any contribution in explaining higher susceptibility of some workers.

SETTINGS AND DESIGN

This was a retrospective occupational injury record study conducted in an industry of eastern India.

MATERIALS AND METHODS

Along with the study of injury records of 5 years, an interview was also conducted involving 726 workers (including permanent and temporary workers both) of the factory.

STATISTICAL ANALYSIS USED

Comparison was made between permanent and temporary workers by using the Mann-Whitney U-test and the chi-square test. A theoretical model of Poisson's distribution was used to compare between expected and real occurrence.

RESULTS

Although two worker groups were very similar in relation to age, level of education, habits, and nature of work, accident frequency and severity rates were found to be significantly higher in temporary workers.

CONCLUSIONS

This study concluded that the higher accident risk of the temporary workers might have been due to the less effective experience as well as due to lack of job security inherent in such workers.

Efficacy of low and high dose inhaled corticosteroid in smokers versus non-smokers with mild asthma

BACKGROUND

Cigarette smokers with asthma are insensitive to short term inhaled corticosteroid therapy, but efficacy when given for a longer duration at different doses is unknown.

METHODS

Ninety five individuals with mild asthma were recruited to a multicentre, randomised, double blind, parallel group study comparing inhaled beclomethasone in doses of 400 microg or 2000 microg daily for 12 weeks in smokers and non-smokers. The primary end point was the change in morning peak expiratory flow (PEF). Secondary end points included evening PEF, use of reliever inhaler, number of asthma exacerbations, spirometric parameters, and asthma control score.

RESULTS

After 12 weeks of inhaled beclomethasone there was a considerable difference between the morning PEF measurements of smokers and non-smokers with asthma (-18 (95% CI -35 to -1), adjusted p = 0.035). Among those receiving 400 microg daily there was a difference between the mean (95% CI) morning PEF (l/min) in smokers and non-smokers (-25 (95% CI -45 to -4), adjusted p = 0.019) and in the number of asthma exacerbations (6 v 1 in smokers and non-smokers, respectively, p = 0.007). These differences were reduced between smokers and non-smokers receiving 2000 microg inhaled beclomethasone daily.

CONCLUSIONS

Compared with non-smokers, smokers with mild persistent asthma are insensitive to the therapeutic effect of low dose inhaled corticosteroid treatment administered for a 12 week period. The disparity of the response between smokers and non-smokers appears to be reduced with high dose inhaled corticosteroid. These findings have important implications for the management of individuals with mild asthma who smoke.

Asthma and cigarette smoking

In most developed countries approximately 25% of adults with asthma are current cigarette smokers. Asthma and active cigarette smoking interact to cause more severe symptoms, accelerated decline in lung function, and impaired short-term therapeutic response to corticosteroids. Cigarette smoking may modify inflammation that is associated with asthma, although there is limited published data on airway pathology in smokers with asthma. To date, the evidence points towards a combination of both heightened and suppressed inflammatory responses in smokers compared with nonsmokers with asthma. The mechanisms of corticosteroid resistance in asthmatic smokers are unexplained, but could be as a result of alterations in airway inflammatory cell phenotypes (e.g. increased neutrophils or reduced eosinophils), changes in the glucocorticoid receptor-alpha to -beta ratio (e.g. overexpression of glucocorticoid receptor beta), and increased activation of pro-inflammatory transcription factors (e.g. nuclear factor-kappaB) or reduced histone deacetylase activity. In conclusion, every effort should be made to encourage asthmatics who smoke to stop, although the effects of smoking cessation upon reversing the adverse effects of tobacco smoke on asthma control, therapeutic response to corticosteroids and airway pathology have yet to be fully elucidated. Alternative or additional therapies to inhaled corticosteroids are needed for asthmatic patients who are unable to quit smoking.

Interleukin-18 levels in induced sputum are reduced in asthmatic and normal smokers

BACKGROUND

IL-18 is a cytokine which is known to have an important role in the development of a Th1 lymphocyte response. As such, it may have a regulatory role in asthma by modifying Th2 lymphocyte responses. Cigarette smoking may amplify the airway inflammation associated with asthma.

OBJECTIVE

This study investigated if IL-18 could be detected in induced sputum from asthmatics and normal subjects and if smoking altered IL-18 levels.

METHODS

Induced sputum was obtained from asthmatic (31 smokers, 35 non-smokers) and normal (20 smokers, 20 non-smokers) subjects. All smokers had a smoking history of > or =15 pack years. IL-18 levels in sputum supernatant were measured by ELISA. IL-18 mRNA expression and cellular localization were assessed by quantitative PCR and immunocytochemistry, respectively.

RESULTS

Smoking was associated with a significant reduction in IL-18 levels (median (interquartile range) - smokers 20 (0-102) pg/mL vs. non-smokers 358 (50-876) pg/mL, P<0.001). This was more pronounced in asthmatics (smokers, 47 (40-64) pg/mL vs. non-smokers, 530 (30-1484) pg/mL; P<0.001) than in normal subjects (smokers, 25 (0-78) pg/mL vs. non-smokers, 247 (50-656) pg/mL; P<0.01). Within each of the smoking and non-smoking groups there was no significant difference in IL-18 levels between asthmatic and normal subjects. There was no correlation between sputum IL-18 levels and any specific cell type in the sputum samples nor serum IgE levels. IL-18 mRNA expression was reduced in asthmatic smokers compared with non-smokers. IL-18 production was localized to sputum macrophages by immunocytochemistry.

CONCLUSIONS

IL-18 is detectable in induced sputum samples from both asthmatic and normal subjects. Cigarette smoking significantly reduces sputum IL-18 levels. This effect is more pronounced in asthmatics than in normal subjects.