[Show abstract][Hide abstract] ABSTRACT: Background
Sublingual immunotherapy (SLIT) applied to type I respiratory allergies is commonly performed with natural allergen extracts. Herein, we developed a sublingual tablet made of pharmaceutical-grade recombinant Bet v 1.0101 (rBet v 1) and investigated its clinical safety and efficacy in birch-pollen allergic patients.Methods
Following expression in E. coli and purification, rBet v 1 was characterized using chromatography, capillary electrophoresis, circular dichroism, mass spectrometry and crystallography. Safety and efficacy of rBet v 1 formulated as a sublingual tablet were assessed in a multi-centre, double-blind, placebo-controlled study conducted in 483 patients with birch pollen-induced rhinoconjunctivitis.ResultsIn-depth characterization confirmed the intact product structure and high purity of GMP-grade rBet v 1. The crystal structure resolved at 1.2 Å documented the natural conformation of the molecule. Native or oxidized forms of rBet v 1 did not induce the production of any proinflammatory cytokine by blood dendritic cells or mononuclear cells. Bet v 1 tablets were well tolerated by patients, consistent with the known safety profile of SLIT. The average adjusted symptom scores were significantly decreased relative to placebo in patients receiving once daily for 5 months rBet v 1 tablets, with a mean difference of 17.0-17.7% relative to the group treated with placebo (p<0.025), without any influence of the dose in the range (12.5 to 50 μg) tested.Conclusion
Recombinant Bet v 1 has been produced as a well-characterized pharmaceutical-grade biological drug. Sublingual administration of rBet v 1 tablets is safe and efficacious in patients with birch pollen allergic rhinoconjunctivitis.This article is protected by copyright. All rights reserved.
[Show abstract][Hide abstract] ABSTRACT: Mast cells are best known for their role in allergic reactions, where aggregation of FcεRI leads to the release of mast cell mediators causing allergic symptoms. The activation also induces a survival program in the cells, i.e., activation-induced mast cell survival. The aim of the present study was to investigate how the activation-induced survival is mediated. Cord blood-derived mast cells and the mast cell line LAD-2 were activated through FcεRI crosslinking, with or without addition of chemicals that inhibit the activity or expression of selected Bcl-2 family members (ABT-737; roscovitine). Cell viability was assessed using staining and flow cytometry. The expression and function of Bcl-2 family members BFL-1 and MCL-1 were investigated using real-time quantitative PCR and siRNA treatment. The mast cell expression of Bfl-1 was investigated in skin biopsies. FcεRI crosslinking promotes activation-induced survival of human mast cells and this is associated with an upregulation of the anti-apoptotic Bcl-2 family member Bfl-1. ABT-737 alone or in combination with roscovitine decreases viability of human mast cells although activation-induced survival is sustained, indicating a minor role for Bcl-X(L), Bcl-2, Bcl-w and Mcl-1. Reducing BFL-1 but not MCL-1 levels by siRNA inhibited activation-induced mast cell survival. We also demonstrate that mast cell expression of Bfl-1 is elevated in birch-pollen-provocated skin and in lesions of atopic dermatitis and psoriasis patients. Taken together, our results highlight Bfl-1 as a major effector in activation-induced human mast cell survival.
[Show abstract][Hide abstract] ABSTRACT: Increasing evidence points to a potential role for members of the transient receptor potential family of cation channels on several features of asthmatic disease. The cough sensitivity to inhaled capsaicin is known to reflect the reactivity of these airway sensory nerves.
The aim was to study, among patients having a positive methacholine provocation and diagnosed with asthma, capsaicin cough sensitivity, sensitivity to methacholine, and levels of exhaled nitric oxide before and after treatment with inhaled steroids, and further, to measure the self-reported impact from environmental irritants.
Eighteen steroid-naïve patients with a positive methacholine test underwent capsaicin inhalation provocation on two occasions, before and after regular use of inhaled steroids over at least 3 months. Comparisons were made to 21 healthy controls. Sensitivity to methacholine and levels of exhaled nitric oxide were measured before and after the treatment. The participants also answered a validated questionnaire regarding environmental irritants.
The patients displayed higher capsaicin cough sensitivity than the controls before the treatment period, but not afterward. Before treatment, capsaicin cough answer correlated significantly with levels of exhaled nitric oxide, but not with methacholine sensitivity. After treatment with inhaled corticosteroids, the capsaicin cough sensitivity and the inflammatory parameters were normalized. In comparison to the control group, the patients reported more affective reactions to and behavioral disruptions induced by environmental irritants.
In steroid-naïve patients with a positive methacholine test, there is a link between that part of the airway inflammation that is reflected by exhaled nitric oxide and that followed by an augmented reactivity of capsaicin-sensitive sensory nerves. This association disappears after steroid treatment.
No preview · Article · Jun 2011 · Journal of Asthma
[Show abstract][Hide abstract] ABSTRACT: Recombinant DNA technology has the potential to produce allergen-specific immunotherapy vaccines with defined composition.
To evaluate the effectiveness of a new recombinant birch pollen allergen vaccine in patients with birch pollen allergy.
A multicenter, randomized, double-blind, placebo-controlled trial was undertaken to compare the following 3 vaccines in 134 adults with birch pollen allergy: recombinant birch pollen allergen vaccine (rBet v 1a), licensed birch pollen extract, natural purified birch pollen allergen (nBet v 1), and placebo. Patients received 12 weekly injections followed by monthly injections of the maintenance dose containing 15 microg Bet v 1 for 2 years.
Significant reductions (about 50%) in rhinoconjunctivitis symptoms (rBet v 1, P = .0002; nBet v 1, P = .0006; birch extract, P = .0024), rescue medication (rBet v 1, P = .0011; nBet v 1, P = .0025; birch extract, P = .0063), and skin sensitivities (P < .0001) were observed in the 3 actively treated groups compared with placebo during 2 consecutive pollen seasons. Clinical improvement was accompanied by marked increases in Bet v 1-specific IgG levels, which were higher in the rBet v 1-treated group than in the birch and nBet v 1-treated groups. New IgE specificities were induced in 3 of 29 patients treated with birch pollen extract, but in none of the 32 rBet v 1-treated or 29 nBet v 1-treated patients. No severe systemic adverse events were observed in the rBet v 1-treated group.
The rBet v 1-based vaccine was safe and effective in treating birch pollen allergy, and induced a highly specific immune response.
No preview · Article · Nov 2008 · The Journal of allergy and clinical immunology
[Show abstract][Hide abstract] ABSTRACT: The pathogenesis of IgE-mediated allergic disease is closely related to the production of T-helper type 2 (Th2) cytokines, which lead to IgE production pivotal for activation of mast cells and basophils. Proliferating T cells along with eosinophils expanded and attracted by Th2 cytokines are major contributors to the late-phase reaction. The activation of these Th2 cells is strongly enhanced by CD23-mediated IgE facilitated allergen presentation (FAP).
The present study aims to investigate the effect of specific immunotherapy (SIT)-induced allergen-specific non-IgE antibodies (blocking antibodies) on IgE binding to allergen, histamine release (HR) and CD23-mediated allergen uptake in antigen-presenting cells.
Competition between IgE and non-IgE for allergen binding was studied by Advia Centaur antibody measurements, passively sensitized basophils were used to study HR and IgE-facilitated binding of allergen to B cells (FAP) was studied by flow cytometry. FAP measurements were performed both with and without the addition of a reference IgE serum, which was included to obtain optimal complex formation. The serum samples were obtained from birch pollen immunotherapy (n=21) or placebo control patients (n=21) before and after 1 and 2 years of treatment.
Statistically significant reduction of all parameters investigated was observed after 1 year of treatment and the effect was maintained during the second year of treatment. There was a clear correlation between the two FAP measurements and between each of them and the level of T cell activation reported upon previously. Moreover, strong correlations were found between changes in FAP, IgE binding and HR.
The present study clearly demonstrates that SIT induces changes in the composition of serum antibodies that inhibit IgE binding, HR and FAP to a similar extent. This suggests that these measurements, individually or in combination, may be used to monitor the immunological effect of SIT, even though direct correlations to changes in clinical parameters could not be demonstrated.
No preview · Article · Jun 2008 · Clinical & Experimental Allergy
[Show abstract][Hide abstract] ABSTRACT: Standardized experimental allergen challenges are usually adopted to investigate the effect of allergen exposure on the lower airways. Environmental (natural) allergen challenges are used less often, mainly because of difficulties in standardizing the method, safety reasons and costs. The aim of this study was to investigate the relationship between an experimental and an environmental bronchial challenge. For this reason a natural challenge model was developed.
Sixty-two patients with a history of cat allergen-induced symptoms involving the lower airways, positive skin prick test, positive in vitro specific IgE to cat allergen and bronchial hyper-responsiveness were included. All 62 patients underwent an experimental challenge in the laboratory followed by an environmental allergen challenge.
All 62 patients developed an early asthmatic response [>or=20% fall in forced expiratory volume in 1 s (FEV1)] in the experimental challenge and 60% (37/62) during the environmental challenge. A late asthmatic response (>or=15% fall in FEV1 within 3-24 h) was seen in 56% (35/62) of the patients after the experimental challenge. Following the environmental challenge 47% (29/62) of the patients developed a late response. Thirty-four per cent (21/62) of the patients developed a late response in both challenge models and 31% (19/62) did not develop a late response in any model. Thus, there was consistency in 65% (40/62) of the patients in both challenge models.
We found consistency in the pattern of response to inhaled allergen between the two challenge models and we believe that experimental bronchial challenge is likely to reflect the development of relevant inflammation in the lower airways after low-dose allergen exposure in the environment.
[Show abstract][Hide abstract] ABSTRACT: Allergen specific immunotherapy modifies the immunologic response to allergen exposure; however, the role of cells composing the innate immune system, such as monocytes and natural killer (NK) cells, in this mechanism is still unclear.
To examine the effect of rush immunotherapy (RIT) on early allergen-induced cytokine production by peripheral blood mononuclear cells from treated cat- and birch-allergic patients.
Twelve allergic patients received RIT, and another 4 served as controls. Blood samples were taken before the start and after 3 days, 1 week, 3 weeks, and 3 months of RIT. Allergen-induced production of interleukin-12 (IL-12) by monocytes and interferon-gamma (IFN-gamma) by NK cells was evaluated by means of flow cytometry.
Before the start of RIT, allergic patients had significantly lower numbers of IL-12+ monocytes compared with healthy subjects (P = .01). The percentage of IL-12+ monocytes increased after 3 months of RIT (P = .003). In the allergic control group, the proportion of IL-12+ monocytes evaluated after 3 months was not different from baseline and was significantly lower compared with that in the RIT group (P = .005). Before treatment, the percentage of IFN-gamma+ NK cells was lower in allergic patients than in healthy subjects (P = .04). The percentage of IFN-gamma+ NK cells increased after 3 weeks (P = .03) and 3 months (P = .01) of RIT.
Restoration of the cytokine imbalance by immunotherapy is not only restricted to the cells of the adaptive immune system but also concerns cells composing the innate immune system.
No preview · Article · Nov 2006 · Annals of allergy, asthma & immunology: official publication of the American College of Allergy, Asthma, & Immunology
[Show abstract][Hide abstract] ABSTRACT: Studies using rush immunotherapy (RIT) have shown that rapid protection can be achieved using protocols allowing a fast increment of allergen dose. We examined the early effects of RIT on basophil numbers and expression of CD203c, production of interleukin (IL)-4 and IL-13 and histamine release by basophils in the peripheral blood of patients treated with immunotherapy and controls.
Twelve patients treated with RIT and 4 untreated controls were included in the study. Any adverse events were evaluated during the incremental phase of RIT. Mononuclear cells were isolated before the start of RIT and 3 days, 1 week, 4 weeks and 3 months after the beginning of the treatment. Histamine release upon allergen stimulation, expression of CD203c and allergen-induced production of IL-4 and IL-13 by basophils were examined.
Significant decreases in blood basophil count (p = 0.02) were observed early in the treatment, returning to baseline values 1 week after the start of RIT. Similarly, histamine release decreased at day 3 (p = 0.02), but returned to pretreatment levels after 1 week. Also, the percentage of IL-4+ and IL-13+ basophils and levels of CD203c expression were markedly reduced early in the treatment. IL-4 and IL-13 production correlated with histamine release and CD203c expression. Histamine release and production of IL-4 and IL-13 by basophils before the treatment correlated with the severity of adverse events during the incremental phase of RIT.
We report the decrease in blood basophil numbers, their lower activation status and the reduced production of IL-4 and IL-13 early in the course of RIT. This early suppression of basophil activation could be one mechanism behind the protective effect of RIT.
No preview · Article · Feb 2006 · International Archives of Allergy and Immunology
[Show abstract][Hide abstract] ABSTRACT: Specific immunotherapy (SIT) modulates immune responses to allergens resulting in improvement of allergic symptoms. However, the mechanisms behind the clinical changes are not clear. Participation of costimulatory molecules on antigen-presenting cells and T cells in the process of antigen recognition is suggested to be of essential importance. The SIT effect on expression of costimulatory molecules has not been earlier examined.
Forty-one birch-allergic patients were treated with SIT or placebo. After 1 year of treatment skin biopsies were obtained 24 h following allergen challenge. Sections were stained with antibodies against: EG2 (eosinophils), CD4 (T cells), CD68 (macrophages), CD1a (Langerhans cells), CD28 (on T cells) and costimulatory molecules (CD80, CD86).
Following allergen challenge number of the CD4(+) and CD68(+) cells increased significantly (P=0.002, 0.0001, respectively) in the placebo, but not in the SIT-treated patients. The difference between groups was significant (P=0.003, 0.01, respectively). The numbers of EG2(+) cells increased significantly in both groups. CD80(+) cell numbers increased in the placebo (P=0.01) but not in the SIT group. The number of CD86(+) cells increased in both groups (placebo, P=0.001; SIT, P=0.01) but significantly less in the SIT group (P=0.05). The numbers of CD28(+) cells increased in the placebo (P=0.001) but remained unchanged in the SIT group. The difference between the groups was significant (P=0.05).
There were lower numbers of cells expressing costimulatory molecules in SIT-treated than in placebo-treated patients. Decreased costimulation may lead to diminished immune response following allergen exposure. This could be an important factor contributing to the clinical improvement after SIT.
No preview · Article · Jan 2005 · Clinical & Experimental Allergy
[Show abstract][Hide abstract] ABSTRACT: Development of asthma is likely to depend on a complex interaction between environmental and genetic factors. Several groups have suggested the gene of the IL-4 receptor alpha chain (IL4R) as a candidate gene for the development of asthma, although association with single polymorphisms has shown contradicting results.
We chose to analyse IL4R gene haplotypes and assess their possible relevance in susceptibility to asthma and to certain clinical phenotypes.
IL4R gene haplotypes were analysed, based on the three markers C-3223T, Q551R and I50V, using the expectation-maximization algorithm, in 170 atopic asthma patients and 350 controls, all adult Swedish Caucasians.
Our data showed significantly higher levels of soluble IL-4R (sIL-4R) in asthma patients compared with controls (P<0.0001). Furthermore, we showed a significant association between the IL4R haplotype containing the alleles T-3223, V50 and R551 (TVR) of the IL4R gene, and susceptibility to atopic asthma, with a frequency of 6.5% in the patients compared with 1% in the controls (P<0.0005). A subgroup of patients with heterozygous or homozygous state for the T-3223, V50 and R551 alleles, also had lower levels of sIL-4R in their circulation compared with patients with homozygous state in the C-3223, I50 and Q551 alleles (P<0.05) and showed less severe asthma according to lung function test (P<0.05). Analysis of single markers showed the T-3223 IL4R allele to associate with lower serum levels of sIL-4 receptor (P<0.0001) and patients carrying the T allele also had more symptoms of active asthma (wheezing, P<0.01; coughing, P<0.05 and breathing difficulties, P<0.01).
Our data suggest that asthmatic patients with low levels of sIL-4 receptor may represent a genetically distinct subgroup of atopic asthma. TVR haplotype analyses confirm the importance of IL4R as a candidate gene for susceptibility to asthma. This finding may have implications for the understanding of the pathogenesis of asthma and possibly for the development of more specific therapies.
No preview · Article · Nov 2004 · Clinical & Experimental Allergy
[Show abstract][Hide abstract] ABSTRACT: The clinical efficacy of specific allergy vaccination (SAV), previously called specific immunotherapy is well documented. The working mechanism of this treatment is not completely known at present. Allergen-specific CD4+ T lymphocytes are activated at extremely low allergen concentrations in vivo possibly as a result of serum IgE-facilitated allergen presentation (S-FAP). Previously, we have shown that this process can be inhibited by long-term birch SAV sera.
In the present study, we have analysed sera from birch-allergic patients in a randomized double-blind, placebo-controlled clinical trial for their ability to mediate S-FAP. Birch-specific IgE levels were not changed after SAV. Bet v 1-specific IgE levels, however, were significantly decreased (P<0.05) and Bet v 1-specific IgG4 levels were strongly increased after SAV (P<0.001). None of these changes were observed in the placebo group. When the sera were tested for their ability to induce S-FAP, a complete abrogation of this effect was noted in the sera from patients receiving active treatment (P<0.001), but not in the control group. This inhibition of S-FAP seemed to be associated with the reduction in the ratio between Bet v 1-specific IgE and IgG4 antibodies in serum, but a clear correlation could not be demonstrated.
In conclusion, the present study clearly shows that SAV leads to an inhibition of the S-FAP needed to obtain optimal T cell activation at the low allergen concentrations present in vivo. This novel mechanism may explain the increased allergen threshold levels found in allergen provocation tests and the reduction of late-phase reactions observed after SAV.
No preview · Article · Mar 2004 · Clinical & Experimental Allergy
[Show abstract][Hide abstract] ABSTRACT: Few placebo-controlled studies have examined the effect of allergen specific immunotherapy (SIT) on early and late phase asthmatic reactions. In this placebo-controlled study we have investigated the effect of 1 year of SIT with standardized birch pollen extract on early and late phase asthmatic reactions in adult asthmatic patients.
Nineteen patients with a history of birch-pollen-induced seasonal symptoms from upper and lower airways, positive skin prick test and in vitro specific immunoglobulin E to birch pollen extract were included. Allergen and methacholine bronchial challenges were performed and blood samples obtained for analyses of total eosinophil count and eosinophil cationic protein (ECP) in serum, before and after 1 year of immunotherapy treatment.
All patients developed early and 16 of 19 both early and late phase asthmatic reactions. A significant increase in allergen dose was required to evoke early asthmatic reaction in the immunotherapy group (P < 0.01) after 1 year of treatment. The difference between the groups was significant (P < 0.01). Also the size of late asthmatic reaction was significantly reduced in the SIT group compared with placebo treated patients (P < 0.01). Twenty-four hours after allergen challenge methacholine sensitivity, number of total eosinophils and ECP increased significantly in the placebo (P < 0.02, P < 0.05 and P < 0.05 respectively), but not in the SIT group.
Allergen SIT with standardized birch pollen extract decreased early and late asthmatic responses following bronchial challenge in pollen allergic patients, thus confirming anti-inflammatory effect of the treatment.
[Show abstract][Hide abstract] ABSTRACT: Consecutive adult patients (n = 70) referred for investigation of suspected asthma were reinvestigated after 5 years with the same diagnostic procedures (airway symptom score, spirometry, methacholine test) as used at the initial investigation. The same diagnostic criteria for asthma, asthma-like disorder (current asthma-like symptoms but negative asthmatests)and chronicobstructive pulmonary disease (COPD) were used at both visits. At the first visit 39/70 patients (56%) fulfilled the asthma criteria, 21/70 (27%) fulfilled the asthma-like criteria and 5/70 (7%) the COPD criteria. Due to lack of current symptoms 5/70 (7%) could not be classified. 5/70 patients (7%) were smokers, however, in the majority (72%) smoke was not tolerated as it induced asthma-like symptoms. At the investigation, 5 years later, 30/39 patients (76%) still fulfilled the asthma criteria and 12/21 patients (57%) still fulfilled the asthma-like criteria. At the 5-year investigation, 10% of patients in the asthma group now fulfilled the asthma-like criteria and 10% of patients in the asthma-like group fulfilled the asthma criteria. It is concluded that asthma as well an asthma-like syndrome may persist for 5 years or more. It is also concluded thatthe two disorders are closely related as patients in the asthma group over time could move into the diagnostic criteria ofthe asthma-like disorder and vice versa.
Full-text · Article · Jan 2003 · Respiratory Medicine
[Show abstract][Hide abstract] ABSTRACT: In sensitized patients, coupling between IgE and FcepsilonRI receptors on mast cells leads to release of proinflammatory mediators and a subsequent influx of inflammatory cells to the affected organ. Omalizumab (Xolair; formerly rhuMAb-E25) binds to circulating IgE, thus preventing induction of the allergic process.
We investigated the effect of treatment with omalizumab on seasonal allergic rhinitis and related changes in inflammatory cell numbers in nasal biopsy specimens.
Patients were randomized to treatment with omalizumab or placebo before the pollen season; the treatment was started and continued during season. Symptoms and use of medication were recorded, and blood samples and nasal biopsy specimens were obtained before and during season. Immunocytochemistry was performed on biopsy sections through use of the following antibodies: anti-CD4, CD8 (T lymphocytes), EG2, and anti-eosinophil peroxidase (eosinophils), anti-tryptase (mast cells), human neutrophil lipocalin (neutrophils), and antibodies against IgE and FcepsilonRI.
During the season, blood eosinophils increased in placebo-treated patients but not in omalizumab-treated patients (P =.01); the difference between the treatment groups was significant (P =.04). Free IgE in serum decreased significantly (P =.0002) in omalizumab-treated patients but not in placebo-treated patients; the difference between the groups was significant (P =.0001). In nasal biopsy specimens, the number of eosinophil peroxidase-positive staining cells increased in the placebo-treated patients (P =.003) but not in the actively treated patients during the season; the difference between the groups was significant (P =.0001). The number of IgE(+) staining cells decreased significantly in the omalizumab group during the season in comparison with the placebo group (P =.04).
The clinical benefit of treatment with omalizumab is associated with an anti-inflammatory effect on cellular markers in blood and nasal tissue.
No preview · Article · Aug 2002 · Journal of Allergy and Clinical Immunology
[Show abstract][Hide abstract] ABSTRACT: Birch pollen is a common allergen in northern, central, and eastern Europe. Earlier studies of specific immunotherapy using birch pollen extract were not placebo-controlled or were only preseasonal. Long-term, placebo-controlled studies with subcutaneously administered standardized birch pollen extract are lacking.
The aim of this study was to evaluate the effect of immunotherapy with birch pollen extract on airway symptoms and use of medication in adult birch pollen-allergic patients in a double-blind, placebo-controlled trial.
Forty-nine patients with histories of birch pollen allergy from the upper and lower airways, positive skin prick test and conjunctival provocation test results, and in vitro specific IgE to birch pollen (Betula verrucosa ) extract were included. Immunotherapy with birch pollen extract was given during 2 consecutive years in a double-blind, randomized, placebo-controlled study. Clinical symptom scores from the upper and lower airways and use of rescue medication were registered throughout the pollen season.
Forty-six patients reached the maintenance dose and were maintained on that dose during the 2-year study. The median symptom scores during the 1997 and 1998 seasons were 1.3 and 2.6, respectively, in the specific immunotherapy group and 2.1 and 4.3, respectively, in the placebo group. The differences between the groups were significant (P =.05 in 1997 and P =.005 in 1998). The placebo group used significantly more rescue medication during both seasons than the specific immunotherapy group (P =.004 for 1997 and P =.004 for 1998).
Specific immunotherapy with birch pollen extract is an effective and safe treatment for reducing clinical allergy symptoms and medication use in birch pollen-allergic patients during the pollen season.
No preview · Article · Jun 2002 · Journal of Allergy and Clinical Immunology
[Show abstract][Hide abstract] ABSTRACT: Eighty-eight patients with a history of exercise-induced respiratory symptoms performed a maximal exercise test in order to study the reasons for stopping the test. There was a wide range of percentage maximal fall in peak expiratory flow (PEF), from minus 3% to 63%, mean 11%, recorded 0-30 min, mean 12 min after the break. In the controls the maximal decrease was 0-16%, mean 6%. Diagnostic criteria for asthma were fulfilled by 48 patients (55%). Of these patients 42% had a fall in PEF > or = 15% (exercise-induced asthma). Of the non-asthma patients 10% had a fall > or = 15%. The most common reason for stopping the exercise in the asthma group was breathing troubles (46%), the most common reason in the non-asthma group was chest pain/discomfort (35%). In about 20% of the patients dizziness and/or pricking sensations in arms or legs indicated hyperventilation as an additional reason for stopping the exercise. It is concluded that other kinds of reaction, than bronchial obstruction such as breathing troubles not directly related to bronchial obstruction and chest pain, may be important factors that can restrict physical capacity in patients with exercise-induced respiratory symptoms.
Full-text · Article · Nov 1999 · Respiratory Medicine