Nasal allergen challenge and environmental exposure chamber challenge: A randomized trial comparing clinical and biological responses to cat allergen (original) (raw)
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Journal of Allergy and Clinical Immunology, 1997
Background: Why allergic subjects may have asthma or rhinitis on allergen exposure remains unclear. Objective: This study was carried out to compare airway responses during environmental allergen challenge (EAC) with quantitative allerge n provocation challenges of the upper and lower airways. Methods: Thirteen subjects with allergy to cats underwent EAC to cats. Lower airway responses during EAC were compared with bronchoprovocation with allergen. Nasal mucosal challenge with allergen-soaked disks were compared with EAC nasal responses. Nonspecific bronchial reactivity was assessed with methacholine: allergen sensitivity was assessed by skin prick tests. RAST. and end-point skin titration. Results: During EAC, the maximal fall in FEV 1 ranged from 6% to 57% (median, 18%) and correlated closely with allergen bronchoprovocation PD2o (Spearman's correlation coefficient [Rs] =-0.85, p < 0.0002). EAC asthmatic responses and allergen bronchoprovocation correlated with methacholine PD2o (R s =-0.85, p = 0.0002 and Rs = 0.83, p = 0.0004, respectively). Nasal provocation and EAC nasal responses correlated with each other but not with lower airway responses. On the basis of EAC and allergen bronchoprovocation responses, seven participants with asthma were identified. This group was significantly more sensitive to inhaled methacholine but was similar to the nonasthmatic group in IgE-mediated sensitivity and nasal responses. Conclusions: The lower respiratory tract is less responsive to allergic and nonallergic stimuli in persons with allergic rhinitis. In persons with asthma during EAC, the response to nebulized cat allergen is also abnormal and correlates closely with their abnormal responsiveness to nonimmunologic stimuli. (
Study of Cat Allergy Using Controlled Methodology—A Review of the Literature and a Call to Action
Frontiers in Allergy, 2022
The prevalence of cat allergen-induced AR is increasing worldwide, prompting its study using controlled methodology. Three general categories of allergen exposure models currently exist for the study of cat allergen-induced AR: natural exposure cat rooms, allergen exposure chambers (AEC), and nasal allergen challenges (NAC). We evaluated existing literature surrounding the use of these models to study cat allergen induced AR using online research databases, including OVID Medline, Embase, and Web of Science. We report that natural exposure cat rooms have been important in establishing the foundation for our understanding of cat allergen-induced AR. Major limitations, including variable allergen ranges and differing study designs highlight the need for a more standardized protocol. In comparison, AECs are an exceptional model to mimic real-world allergen exposure and study long-term implications of AR with large sample sizes. Existing AECs are limited by heterogeneous facility design...
Annals of Allergy, Asthma & Immunology, 2003
Background: Treatment of cat allergy normally entails removal of the cat from the household, but cat owners are often unwilling to part with their pets, despite clinically relevant allergies. Objective: To determine whether levels of Fel d 1 can be reduced without removal of the cat and whether this will affect symptoms of cat allergy. Methods: Cat-allergic patients underwent randomization to either a group instructed in environmental control (EC) and a group with unchanged environment (UE). Dust samples were obtained and settled Fel d 1 measured by enzyme-linked immunosorbent assay. Patients recorded daily nasal inspiratory flow rates. At baseline, 3 months, and 8 months, patients underwent symptom evaluation. Results: Eighteen patients were randomized to the EC group and 22 to the UE group; the final number completing the study was 31, 15 in the EC group, and 16 in the UE group. At 8 months, home Fel d 1 levels had diminished to 6.8% of baseline levels in the EC group, whereas no reduction in levels was noted in the UE group. In the EC group, significant improvements were found in nasal inspiratory flow rate and symptoms compared with the UE group. Patients did not have difficulties adhering to EC measures. Conclusion: A decrease in the allergen load was found in the EC group, which had a significant effect on symptoms of nasal allergy.
Bronchial Responsiveness in Atopic Adults Increases with Exposure to Cat Allergen
American Journal of Respiratory and Critical Care Medicine, 2007
Rationale: The association of asthma with sensitization and allergen exposure is known to be complex. There have been few studies of bronchial responsiveness in relation to both risk factors in adults. Objectives: To determine the relation of bronchial responsiveness to allergen exposure and IgE sensitization in a community study taking into account the major determinants of bronchial responsiveness in adulthood. Methods: Cross-sectional data were drawn from 1,884 participants in 20 centers in the European Community Respiratory Health Survey follow-up, which included measurement of house dust mite and cat allergen in mattress dust samples, and IgE sensitization to four allergens. Bronchial responsiveness to methacholine was expressed as a continuous variable, and analyzed by multiple regression. Measurements and Main Results: The trend toward greater bronchial responsiveness with increasing exposure to cat allergen was greater in those sensitized to any of the four allergens than those not sensitized (p ϭ 0.001); there was no significant interaction between cat sensitization and Fel d 1 exposure. No trend was found with house dust mite allergen exposure. The difference in bronchial responsiveness between those exposed to the highest levels compared with the lowest was approximately ؊2.02 doubling doses of PD 20 (95% confidence interval, ؊3.06 to ؊0.97), and nearly as great in those exposed to more moderate levels. Conclusions: Cat allergen exposure at moderate levels may be harmful to all atopic adults. The clinical implication is that it is insufficient to test patients with asthma for cat sensitization; all atopic individuals may benefit from reduced cat exposure.
Small airways response to naturalistic cat allergen exposure in subjects with asthma
Journal of Allergy and Clinical Immunology, 2006
Background: It is currently unclear whether the small airways (diameter < 2 mm) contribute significantly to late asthmatic reactions to inhaled allergen. Objectives: We sought to determine whether naturalistic exposure to cat allergen induced late responses in the small airways as measured by pulmonary function testing and high-resolution computed tomography (HRCT) of the chest performed at end-expiration. Methods: In a group of 10 subjects with cat-induced asthma, physiologic studies (spirometry and lung volumes, including closing volume) and HRCT were performed before and 6 and 23 hours after a cat room challenge that caused a 20% or greater acute fall in FEV 1 . Results: There was no significant decline in FEV 1 at 6 or 23 hours after cat exposure. Forced expiratory flow at 25% to 75% of forced vital capacity was significantly decreased at 6 hours after the challenge and returned to normal by 23 hours. HRCT image analysis as well as closing volume demonstrated increased air trapping from baseline at both 6 and 23 hours after the challenge. In addition, image analysis demonstrated a significant increase in small airways hyperresponsiveness to methacholine at 23 hours after the challenge. No significant mean changes were noted in lung volumes at either 6 or 23 hours or in PC 20 FEV 1 at 23 hours postchallenge. Conclusion: These findings demonstrate that naturalistic exposure to cat allergen results in significant small airways obstruction and hyperresponsiveness persisting for at least 23 hours, at which time these changes cannot be detected by conventional physiologic measures. Clinical implications: Physiologically silent distal lung inflammation persists after an antigenic challenge. (J Allergy Clin Immunol 2006;118:1075-81.)
Allergy, 2007
Abbreviations: BHR, bronchial hyper-responsiveness; EAR, early asthmatic response; EnBPT, environmental bronchial provocation test; ExBPT, experimental bronchial provocation test; FEV 1 , forced expiratory volume in 1 s; LAR, late asthmatic response; MPT, methacholine provocation test; PC 20 , concentration of inhaled methacholine at 20% FEV 1 fall; PD 20 , allergen provocation dose at 20% FEV 1 fall; SIT, specific immunotherapy; SPT, skin prick test; SQ, standard quality.