Early and late allergic bronchial reactions: physiological characteristics

Area of Science:

• Allergy and Immunology
• Pulmonary Medicine
• Respiratory Physiology

Background:

• Asthma is a chronic respiratory disease characterized by airway inflammation and hyperresponsiveness.
• Allergic triggers are common causes of asthma exacerbations, leading to diverse physiological responses.
• Understanding the patterns of early and late asthmatic reactions is crucial for effective management.

Purpose of the Study:

• To investigate the pulmonary physiological changes associated with early, late, and dual asthmatic reactions.
• To compare the severity and characteristics of lung function alterations in different reaction patterns.
• To explore the involvement of small airways in dual asthmatic responses.

Main Methods:

• Twenty-four asthma patients underwent allergen bronchial provocation.
• Lung function tests, including FEV1, RV, TGV, and maximum mid-expiratory flow rates (air and He/O2 mixture), were performed.
• Measurements were taken before and 6 hours after allergen challenge to assess early and late responses.

Main Results:

• Eighteen patients showed bronchial obstruction, with 11 having isolated early reactions, 5 dual reactions, and 2 only late reactions.
• Dual reactors exhibited significantly greater changes in FEV1, RV, and TGV during the early phase compared to isolated early reactors.
• Four of five dual reactors showed decreased helium response post-challenge, suggesting small airway involvement; increased alveolar plateau slope (phase III) and CC% were also observed.

Conclusions:

• Dual asthmatic reactions involve widespread pulmonary physiological changes, affecting airways generally and mimicking severe asthma.
• Patients with dual reactions typically display stronger responses compared to those with isolated early reactions.
• Late asthmatic reactions can occur independently of immediate early responses in some individuals.