Airway responses to antigen challenge in allergic rhinitis and allergic asthma

The density dependence of the maximum expiratory flow-volume curve, functional residual capacity (FRC), and specific airway conductance (SGaw) were determined before and during bronchial provocation with ragweed extract in 27 subjects with ragweed hypersensitivity and a history of either bronchial asthma (16 subjects) or allergic rhinitis (11 subjects). Mean baseline SGaw was significantly lower while mean volume of isoflow (Visov) and FrC were significantly higher in subjects with bronchial asthma. During antigen challenge, 10 of 16 subjects with bronchial asthma (63%) and five of 11 subjects with allergic rhinitis (45%) showed a greater than 35% decrease in SGaw ("reactors"): mean relative decreases in SGaw from baseline were 46% and 53%, respectively. The remaining subjects showed a less than 35% decrease in SGaw ("nonreactors") with mean relative decreases of 9% (allergic asthma) and 6% (allergic rhinitis). Mean Visov increased in all subjects with bronchial asthma and in eight of 11 subjects with allergic rhinitis. A significant increase in FRC (6%) was seen only in the "reactors" with bronchial asthma. Following antigen challenge, the beta adrenergic agonist, isoetharine, increased SGaw and decreased Visov. We conclude that in asymptomatic subjects with ragweed hypersensitivity, (1) central and peripheral airway function is more abnormal in subjects with bronchial asthma than in subjects with allergic rhinitis, (2) subjects of both groups show quantitatively and qualitatively comparable airway responses during antigen challenge with a decrease in SGaw or an increase in Visov, possibly representing increase in central and/or peripheral airflow resistance, respectively, (3) Visov may be a more sensitive indicator of airway response to antigen challenge than SGaw, and (4) the bronchodilator effects of a beta adrenergic agonist on antigen-induced bronchospasm are similar in both groups.     

The atopic march: progression from atopic dermatitis to allergic rhinitis and asthma

Atopic dermatitis (AD) is an inflammatory disease characterized by pruritic skin lesions. The pathogenesis of AD may include disrupted epidermal barrier function, immunodysregulation, and IgE-mediated sensitization to food and environmental allergens. AD is also part of a process called the atopic march, a progression from AD to allergic rhinitis and asthma. This has been supported by multiple cross-sectional and longitudinal studies and experimental data. Research on the mechanisms of AD has been centered on the adaptive immune system with an emphasis on the T-helper 1 (Th1)-Th2 paradigm. Recently, the conceptual focus has largely shifted to include a primary defect in the epithelial barrier as an initial event in AD providing a significant insight into the disease initiation and pointing to a complex secondary interplay of environmental and immunological sequelae with barrier disruption. Further understanding of AD will help the development of more effective treatment for AD and ultimately, preventative algorithms for the atopic march. In this review we highlight recent advances in our understanding of the pathogenesis of AD and the atopic march.     

T cell responses in allergic rhinitis, asthma and atopic dermatitis

Although clinical responses to allergens have been shown to primarily involve IgE antibodies, there is often no clear correlation between the amount of allergen-specific IgE present in the serum and the nature and severity of allergic symptoms. This observation raises the question of the possible role of non-IgE mediated types of immune responses in this reaction. It is not known to what extent components of T cell-mediated immunity are involved in IgE-mediated reactions but several observations suggest an association between atopic disease and alterations in cellular immune function. These include the frequent association of high serum IgE levels with: (i) several of the primary and acquired immunodeficiencies characterized by partial T cell deficiency; (ii) the defective cell-mediated immunity and resultant recurrent infections seen in the hyper-IgE syndrome; and (iii) the sudden rise in serum IgE levels associated with reduced numbers of suppressor T cells in bone marrow transplant recipients during the acute graft vs host disease. In this review, we will examine the recent evidence suggesting that the T lymphocyte may play a primary role in the pathogenesis of atopic disorders.     

The importance of maximal airway response to methacholine in the prediction of asthma development in patients with allergic rhinitis

BACKGROUND: Allergic rhinitis is a known predictor and correlate of asthma incidence. However, it is not clear which patients with allergic rhinitis are at greater risk of the development of asthma. OBJECTIVE: The aim of this study was to investigate whether airway hypersensitivity and/or increased maximal response on the dose-response curve to methacholine would predict the development of asthma in subjects with allergic rhinitis. METHODS: One hundred and forty-one children with allergic rhinitis were prospectively studied for 7 years. At the initiation of the study, bronchial provocation test with methacholine using a stepwise increasing concentration technique was performed to measure PC(20) (provocative concentration causing a 20% fall in FEV(1)) and maximal response. Each subject was evaluated at least every 6 months and details of asthmatic symptoms or signs experienced during the intervening period were taken. RESULTS: Twenty of 122 subjects available for the follow-up developed asthma. Nine (19.6%) of 46 hypersensitive (PC(20) < 18 mg/mL) subjects developed asthma, compared with 11 (14.5%) of 76 normosensitive subjects (P = 0.462). Eight (32%) of 25 subjects without maximal response plateau developed asthma, compared with 12 (12.4%) of 97 subjects with maximal response plateau (P = 0.018). Score test for trend revealed a significant association between the level of maximal response (P = 0.007), but not the degree of methacholine PC(20) (P = 0.123), and the future development of asthma. CONCLUSION: An increased maximal airway response to methacholine is shown to be a better predictor for the future development of asthma in patients with allergic rhinitis, than airway hypersensitivity to methacholine.     

The comparison of allergic responses to Dermatophagoides farinae between bronchial asthma and allergic rhinitis

The allergic responses of 52 bronchial asthma patients who exhibited a positive bronchoprovocation test with house dust and 50 allergic rhinitis patients who had positive RAST results to Dermatophagoides farinae (D. farinae) were studied, including the measurement of D. farinae-specific IgE using D. farinae-RAST, total IgE and skin reactivity to D. farinae and house dust. A comparison between the allergic rhinitis group in which methacholine PC20 was more than 4.66 mg/mL and the allergic rhinitis group which presented negative results in the methacholine bronchial challenge test, indicated that there were significant differences in skin test reactivity and the ratio of specific IgE to total IgE (P less than .05). The allergic responses we observed were not different between the allergic rhinitis group in which methacholine PC20 was less than 4.66 mg/mL (asthmatic range of methacholine PC20) and the allergic rhinitis group in which methacholine PC20 was more than 4.66 mg/mL. When comparing the bronchial asthma group which showed positive results in D. farinae-RAST and the allergic rhinitis group in which methacholine PC20 was less than 4.66 mg/mL, significant differences were noted in total IgE level (P less than .05). These findings suggest that the development of bronchial asthma in patients with allergic rhinitis might be predicted by measuring the degree of bronchial hyperreactivity and their allergic responses.     

Lower airway inflammatory responses to repeated very-low-dose allergen challenge in allergic rhinitis and asthma

BACKGROUND: Low-dose allergen challenge (LDAC) may be a useful tool for studying the capacity of allergens to induce airway inflammation in atopic subjects. OBJECTIVE: To evaluate lower airway inflammatory changes following repeated inhalation of very low doses of allergen (VLDAC) in non-asthmatic subjects with allergic rhinitis (NAAR) compared with mild allergic asthmatic subjects (AA). METHODS: Fourteen NAAR and 11 AA were seen out of the pollen season and had skin prick tests with common aeroallergens. Baseline spirometry (S) and methacholine challenge (MC) were done and blood and induced sputum (IS) differential cell counts were obtained. Each subject underwent VLDAC on four consecutive mornings with a relevant allergen. S, MC, and blood and IS samplings were repeated 6 h after the second and fourth VLDAC and one week later. RESULTS: Although there were, as expected, no changes in FEV1 or PC20 in either group, mean percentage eosinophils on IS were significantly increased in NAAR on day 2 of VLDAC and decreased in all but one subject on day 4, with a tendency to return to baseline levels one week later. In AA, there was a non-significant trend for sputum eosinophils to increase on day 2; four subjects showed a decrease of eosinophils on day 4 of VLDAC. There was a correlation between eosinophil cationic protein (ECP) levels and eosinophil counts in NAAR throughout the study. There were no variations in other sputum cells or blood inflammatory cells. CONCLUSION: VLDAC can increase the percentage of eosinophils in IS of NAAR subjects without associated respiratory symptoms nor physiological modifications. A reduction in eosinophilic response despite repeated exposure, more common in NAAR subjects, suggests an adaptation process that needs to be further evaluated.     

Effect of deep inspiration on airway conductance in subjects with allergic rhinitis and allergic asthma

We measured specific airway conductance ($\text{Gaw}\text{Vtg}$) in a body plethysmograph before and after a deep inspiratory maneuver in 8 subjects with allergic rhinitis and 8 subjects with allergic asthma. In hay fever subjects deep inspiration had no effect on $\text{Gaw}\text{Vtg}$ if it was performed in the control state; however, when methacholine-induced bronchoconstriction was present, deep inspiration transiently increased $\text{Gaw}\text{Vtg}$. In asthmatic subjects deep inspiration was followed by a transient fall in baseline $\text{Gaw}\text{Vtg}$ in the control state; however, when bronchoconstriction was present, deep inspiration was followed by small and variable changes in $\text{Gaw}\text{Vtg}$ in 7 subjects and marked improvement in $\text{Gaw}\text{Vtg}$ in 1 subject. In asthmatic subjects the bronchoconstrictor response to deep inspiration performed in the control state is thought to be due to reflex changes in bronchomotor tone mediated by cholinergic (vagal) nerve pathways. Like asthmatic subjects, hay fever subjects also possess cholinergic-mediated airway hyperreactivity compared with normals. Our results indicate that, in spite of their increased airway reactivity, hay fever subjects respond more like normal subjects than like asthmatic subjects after a deep inspiratory maneuver.     

A comparison of topical budesonide and oral montelukast in seasonal allergic rhinitis and asthma

BACKGROUND: Allergic rhinitis and asthma commonly coexist and are both mediated by similar inflammatory mechanisms. Leukotriene antagonists may therefore be an alternative to corticosteroid therapy. OBJECTIVE: To compare oral montelukast with inhaled plus intranasal budesonide in patients with seasonal allergic rhinitis and asthma. PATIENTS AND METHODS: A single-blind double-dummy placebo-controlled crossover study was performed comparing once daily 10 mg oral montelukast with 400 microg inhaled plus 200 microg intranasal budesonide in 12 patients with allergic rhinitis and asthma: mean (S.E.) age 34.0 years (2.7), forced expiratory volume in 1 s (FEV1) 91.2 (3.8)% predicted. Each treatment was for 2 weeks with a 1-week placebo run-in and washout. Measurements were made after each active treatment and placebo for: adenosine monophosphate bronchial challenge, exhaled and nasal nitric oxide. Patients also recorded their domiciliary peak expiratory flow, nasal peak inspiratory flow, asthma and seasonal allergic rhinitis symptoms. RESULTS: There were no significant differences between the placebos for any measurement. For adenosine monophosphate PC20, geometric mean fold differences (95% confidence interval (CI) for difference) were 6.4 (2.2-18.6) for placebo vs. budesonide, 2.9 (1.0-8.4) for placebo vs. montelukast, and 2.1 (1.1-4.5) for budesonide vs. montelukast. For exhaled nitric oxide (p.p.b.) there was significant (P < 0.05) suppression with both montelukast (10.9) and budesonide (10.1) compared with placebo (18.8). For nasal nitric oxide and nasal peak flow there were only significant differences with budesonide compared with placebo. Both treatments reduced total seasonal allergic rhinitis symptoms but only budesonide had a significant effect on nasal symptoms. CONCLUSION: Once-daily inhaled plus intranasal budesonide and once daily montelukast showed comparable efficacy on lower airway, but only the budesonide had significant efficacy on upper airway inflammatory markers. Both treatments significantly reduced allergic rhinitis symptoms.     

The airway inflammatory response in allergic asthma and its relationship to clinical disease

Endobronchial biopsy and lavage studies have revealed the presence of mast cell, eosinophil, T-lymphocyte and epithelial cell activation in asthma, along with the structural changes of tissue eosinophil infiltration, loss of superficial columnar ciliated epithelial cells and enhanced collagen deposition in the laminar reticularis. As these cellular and structural changes underlie the clinical features of asthma, i.e., symptom expression, variable airflow obstruction and bronchial hyperresponsiveness, an understanding of their induction and regulation is essential to the understanding of the asthmatic process. The acute airway response to allergen has been studied by the technique of local endobronchial allergen challenge with direct airway sampling in asthma. These studies identify allergen-mast cell interaction as the initial airway event, with mediator release inducing bronchoconstriction and enhancing vascular permeability. As preformed cytokines are present in mast cells, cytokine release from this cell population is likely to initiate the process of endothelial cell activation, with upregulation of cell adhesion molecules, and tissue cell recruitment. Subsequent cytokine elaboration from airway macrophages and T-lymphocytes will perpetuate this response while in chronic clinical disease T-lymphocytes, mast cells, matrix tissue, epithelial cells and eosinophils themselves are all likely to contribute to the cytokine pool within the airways and thus to the regulation of inflammatory cell migration and activation.     

Large airway constriction in allergic rhinitis

Extensive pulmonary function tests, including most of the sensitive new techniques capable of detecting small airways obstruction, were performed in 16 asymptomatic patients with allergic rhinitis and 31 normal control subjects. Mean flow rates, lung volumes, and results of tests measuring airways closure, distribution of ventilation, and diffusing capacity for carbon monoxide/alveolar volume did not differ significantly between the groups. Airways resistance (R_AW) was significantly higher and specific conductance (SG_AW) was significantly lower in subjects with rhinitis. Following administration of nebulized isoproterenol, R_AW decreased (p < 0.001) and SG_AW increased (p < 0.001) to mean values statistically indistinguishable from results obtained in control subjects. Individual results were normal for all tests except R_AW and SG_AW which were both abnormal in 3 subjects with rhinitis. The results of this investigation indicate that asymptomatic subjects with allergic rhinitis have large airway (trachea and/or major bronchi) narrowing due to bronchoconstriction and no evidence of diffuse, or small airways, obstruction.     

Deficient Concanavalin-A-induced suppressor-cell activity in patients with bronchial asthma, allergic rhinitis and atopic dermatitis

Concanavalin-A (Con-A)-induced suppressor activity against the proliferative response of autologous lymphocytes to phytohaemagglutinin (PHA) was examined in the peripheral-blood lymphocytes from fourteen patients with bronchial asthma, ten patients with allergic rhinitis and eleven patients with atopic dermatitis and compared with eleven simultaneously studied healthy normals. Eight of fourteen patients (57%) with bronchial asthma, eight of ten patients (80%) with allergic rhinitis and five of eleven patients (45%) with atopic dermatitis demonstrated deficient Con-A-induced suppressor function. Abnormal suppressor-cell functions could play an important role in the pathogenesis of atopic states.     

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

BACKGROUND: In allergic diseases, eosinophils in affected tissues release granule proteins with cytotoxic, immunoregulatory, and remodelling-promoting properties. From recent observations, it may be assumed that eosinophils degranulate already in circulating blood. If degranulation occurs in the circulation, this could contribute to widespread systemic effects and provide an important marker of disease. OBJECTIVE: To determine the degranulation status of circulating eosinophils in common allergic diseases. METHODS: Using a novel approach of whole blood fixation and leucocyte preparation, the granule morphology of blood eosinophils from healthy subjects, non-symptomatic patients, symptomatic patients with asthma, asthma and Churg-Strauss syndrome, allergic rhinitis, and atopic dermatitis was evaluated by transmission electron microscopy (TEM) and eosinophil peroxidase (TEM) histochemistry. Plasma and serum levels of eosinophil cationic protein were measured by fluoroenzymeimmunoassay. Selected tissue biopsies were examined by TEM. RESULTS: Regardless of symptoms, circulating eosinophils from allergic patients showed the same granule morphology as cells from healthy subjects. The majority of eosinophil-specific granules had preserved intact electron-density (96%; range: 89-98%), while the remaining granules typically exhibited marginal coarsening or mild lucency of the matrix structure. Abnormalities of the crystalline granule core were rarely detected. Furthermore, granule matrix alterations were not associated with any re-localization of intracellular EPO or increase in plasma eosinophil cationic protein. By contrast, eosinophils in diseased tissues exhibited cytolysis (granule release through membrane rupture) and piecemeal degranulation (loss of granule matrix and core structures). CONCLUSION: In symptomatic eosinophilic diseases, circulating blood eosinophils retain their granule contents until they have reached their target organ.     

Allergy screening in asthma and allergic rhinitis

To detect atopy by a screening method employing skin prick testing with a limited number of allergens, the test results of 939 patients with allergic airways diseases were analysed. It was found that an allergen panel consisting of cat, timothy and house dust mite could detect 85% of atopic patients with asthma and/or rhinitis. For subgroups of patients the results were even more favourable. Thus 98% of atopic patients with seasonal allergic rhinitis were detected by an allergen panel consisting of timothy, birch and mugwort. It is concluded that screening methods using only three of four allergens could be used for detecting atopy in patients with airways diseases. The method should be most valuable for in vitro tests used in combination with standardized questionnaires.