Symptom Assessment of Patients with Allergic Rhinitis Using an Allergen Exposure Chamber
March 3rd, 2023
A protocol for conducting a challenge in an allergen exposure chamber (AEC) facility is presented. AECs have proven to be safe and effective tools for the induction of allergic symptoms or as an endpoint in the efficacy testing of allergen immunotherapy due to their ability to maintain stable particle concentrations and environmental conditions.
Allergen exposure chambers allow controlled exposure to allergenic and non-allergenic urban particles in a confined environment. They are used for controlled challenges and mimicking natural exposure. The allergen exposure chamber facilitates the observation of various clinical endpoints, particularly objective measures such as nasal obstruction or secretion, and subjective parameters evaluated by the patient.
Allergen exposure chambers are available tool for the assessment of primary endpoints in clinical studies especially in allergen-specific immunotherapy and pharmacotherapy of allergic respiratory diseases. To begin, vacuum all the surfaces, including the furniture and the floor, with a high-efficiency particulate air filter vacuum cleaner. Clean all washable surfaces with a moisture wipe including the furniture, the walls, windows, and floor.
Turn on the compressor which circulates air through the allergen exposure chamber or AEC system and then turn on the floor and ceiling fans so that the incoming air is regularly mixed under turbulent conditions. Set the injection length and break between injections of the feeder control station to their maximum values to blow the allergen supply duct with clean air for 30 minutes. To check the contamination by the allergen, go to the main menu on the laser particulate counter and select configuration, followed by sample, zero cycles, one-minute delay.
Hold to one minute. Set sample to one minute and units to cubic meters. Again, go to the main menu and select configuration followed by particles, then select all options.
Turn on the compressor, which circulates air through the AEC, and adjust the temperature to 21 plus or minus 0.5 degrees Celsius on the temperature control system. Turn on the floor and ceiling swirl fans and the humidifier on the feeder control station. Set the knob air supply to the position between 40 to 100%to set the air change per hour to between 50 and 20.
Then control the relative humidity and carbon dioxide concentration during the trial by adjusting the air supply. After setting the laser particle counter to count the particles for one minute, go to the main menu and select configuration followed by particles. Take 5, 10, and 20 micrometers to set the value for the monitored particles in the range of zero to 20 micrometers.
Place the allergen in the feeder and set the injection length to 100 milliseconds and the break between injections to 1.5 minutes on the feeder control station. Before the participants enter the AEC, request them to put on disposable coveralls with a hood to guard against the infiltration of non-allergen particles and the potential contamination of clothing. Give them a containing all the necessary instrument disposable tips for use during the examination:a remote controller for the questionnaire, one pack of handkerchiefs and a biohazard plastic bag for nasal secretion.
Instruct the participants to place any used handkerchiefs in the plastic bag. Each participant would spend a total of 120 minutes inside the AEC. All the tests will be performed during this time.
For the participant's comfort, perform the tests individually in a room next to the AEC. For the symptoms survey, display the questions on the TV screen and ask the participants to self-assess before the challenge and every 30 minutes during the challenge by selecting the number on the remote that corresponds to the severity of each symptom. For the acoustic rhinometry, place the appropriate tip of the rhinometer head against the participant's nostril.
Check if it is tight. Ask the participants to hold their breath for three seconds and then start the program. Repeat for the other nostril with the appropriate tip.
Perform the acoustic rhinometry test three times before the challenge, 60 minutes after the challenge, and 120 minutes after the challenge. For the peak nasal inspiratory flow test, ask the participants to deflate their lungs deeply. Place the disposable inspiratory flow meter mask connected with the flow meter onto their face and then breathe in through the nose to the maximum.
For the peak expiratory flow rate, ask the participants to take in as deep a breath as possible. Put their lips around the peak flow matter disposable tip and exhale quickly and forcefully. For spirometry, put the disposable tip on the spirometer and then put on the nose plug.
Finally, instruct them to take a deep breath and a strong exhalation without unnecessary delay which can only be interrupted when the spirometer gives a signal. After the trial is over, instruct the participants to place the unused handkerchiefs in the same bag and collect all the bags. To determine the weight of nasal secretions, weigh used handkerchiefs in plastic bags and subtract the weight of the unused handkerchiefs and plastic bags from each measurement.
Check the measured data. And after each trial, download the data from the computer to an external drive and analyze it. The results of the stability of the environment in the AEC during the trial are shown in this figure.
The particle concentration was assessed and found to be in the range of zero to 20 micrometers by the laser particle counter. The target value for the concentration of house dust mites allergens was 5, 000 particles per cubic meter. For comparison, a trial where no allergen was used is shown.
The AEC environment was monitored throughout the operation time for humidity, carbon dioxide concentration, and temperature. The house dust might triggered allergy subjects with allergic rhinitis and healthy controls including eight and seven participants were exposed to house dust mite allergen concentrations of 5, 000 particles per cubic meter in the AEC. Nasal secretion weight, nasal symptoms, minimal cross-sectional area in acoustic rhinometry, peak nasal inspiratory flow, peak expiratory flow rate, and forced expiratory volume in the first second were evaluated and the results are presented as individual replicates with the mean value.
It is essential to provide stable and sufficiently high allergen concentrations throughout the whole trial in the allergen exposure chamber. The validation of allergen exposure chambers against other allergens, especially rare ones like cat, dog dander, molds, weeds, or similar, will enable assessment of other sensitizations in various subjects.
Overview
This article presents a protocol for conducting challenges in an allergen exposure chamber (AEC) facility. AECs are effective for inducing allergic symptoms and testing allergen immunotherapy.
Key Study Components
Area of Science
- Allergy research
- Clinical trials
- Respiratory diseases
Background
- Allergen exposure chambers allow controlled exposure to allergens.
- They facilitate the observation of clinical endpoints.
- They are essential for assessing primary endpoints in clinical studies.
- Environmental conditions in AECs can be precisely controlled.
Purpose of Study
- To outline a protocol for using AECs in allergy research.
- To evaluate the effectiveness of allergen immunotherapy.
- To assess various clinical endpoints related to allergic responses.
Methods Used
- Cleaning and preparing the AEC environment.
- Monitoring particle concentration and environmental conditions.
- Conducting various tests on participants, including acoustic rhinometry and spirometry.
- Collecting and analyzing data on nasal secretions and symptoms.
Main Results
- Stable environmental conditions were maintained during trials.
- Particle concentrations were effectively monitored.
- Allergic responses were measured through various clinical endpoints.
- Results indicated significant findings related to allergen exposure.
Conclusions
- AECS are valuable tools for allergy research.
- They provide a controlled environment for testing allergen responses.
- The protocol outlined can enhance the reliability of clinical studies.
Frequently Asked Questions
Executive Industry Relevance
Allergen exposure chambers (AECs) provide a rigorously controlled environment for evaluating allergic responses, enabling reproducible assessment of candidate therapies and diagnostics in respiratory disease research. Their ability to standardize allergen delivery and symptom measurement supports predictive confidence at key inflection points in allergy drug development. This platform is directly relevant for portfolio triage and mechanistic de-risking in immunotherapy and respiratory pipeline programs.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables precise interrogation of allergic response pathways under controlled exposure conditions.
- Supports functional validation of targets by quantifying symptom onset and severity in sensitized subjects.
- Facilitates mechanistic de-risking by isolating allergen-specific effects from environmental confounders.
Screening & Assay Development
- Provides validated, reproducible biological systems for downstream pharmacological and immunotherapy screening.
- Standardizes symptom scoring and objective readouts such as TNSS, ARM, and PNIF for assay development.
- Enables reliable, quantitative evaluation of candidate interventions in a scalable, platform-ready format.
Translational & Preclinical Research
- Aligns clinical endpoints with disease-relevant biomarkers for translational continuity.
- Supports risk-adjusted advancement decisions by providing robust, cross-comparable data on intervention efficacy.
- Facilitates preclinical-to-clinical bridging by mimicking natural allergen exposure in a controlled setting.
Pipeline & Workflow Integration
The AEC protocol integrates from early discovery through lead identification and preclinical validation, supporting iterative hypothesis testing and candidate selection.
- Discovery Biology: Enables hypothesis-driven testing of allergen response mechanisms and target engagement.
- Screening: Delivers standardized, reproducible symptom and physiological readouts for compound evaluation.
- Analytics: Provides quantitative outputs (e.g., TNSS, ARM, PNIF, PEFR, FEV1) for robust statistical comparison across conditions.
- Translational Research: Bridges preclinical findings with clinical endpoints relevant to allergic rhinitis and immunotherapy trials.
- Enterprise Reuse: Establishes a reusable, validated platform for ongoing respiratory and allergy research programs.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence and reduces mechanistic ambiguity in allergy target validation.
- Operational Value: Delivers standardized, reproducible, and scalable allergen challenge protocols.
- Strategic Value: Improves go/no-go decision quality and capital efficiency by enabling robust, early-stage efficacy assessment.
- Portfolio Impact: Supports risk-adjusted prioritization and advancement of respiratory and immunotherapy assets.
Implementation Considerations
- Requires expertise in allergen handling, respiratory physiology, and clinical endpoint assessment.
- Demands specialized instrumentation for environmental control and quantitative symptom measurement.
- Necessitates rigorous cross-team standardization of protocols and data collection.
- Adaptation to additional allergens or disease models may require further validation.
- Stable allergen concentration and environmental monitoring are critical for reproducibility and safety.
Biopharma FAQs
Chapters in this video
0:04
Introduction
1:03
Cleaning the AEC
2:26
Operating the AEC: Environment
3:10
Generation and Counting of Particles
3:45
Examination in the Cabin and Clinical Endpoints
6:45
Results: Stability of the Environment in the AEC During the Trial and Different Endpoints During the AEC Challenge in Patients
8:01
Conclusion
