Increased bronchovascular permeability after allergen exposure in sensitive asthmatics

Area of Science:

• Pulmonary Medicine
• Immunology
• Allergy Research

Background:

• Asthma is a chronic inflammatory disease of the airways.
• Allergen exposure is a primary trigger for asthma exacerbations.
• The precise mechanisms of allergen-induced airway changes require further elucidation.

Purpose of the Study:

• To investigate if allergen exposure increases bronchovascular permeability in sensitive asthmatics.
• To quantify changes in serum protein levels in bronchoalveolar lavage (BAL) fluid post-allergen challenge.
• To assess the movement of serum proteins into the lung tissue after allergen exposure.

Main Methods:

• Measurement of total and specific serum proteins in BAL fluid before and after local allergen challenge in 15 sensitive asthmatics.
• Evaluation of serum protein distribution coefficients in airway fluids.
• Tracking of intravenously administered 99mTc-albumin in allergen-exposed airways of 10 subjects.
• Analysis of BAL fluid from 4 asthmatics 2-4 hours after aerosol challenge.

Main Results:

• Significant increase in total protein in BAL fluid of asthmatics after allergen challenge (0.13 +/- 0.02 mg/ml vs. 0.08 +/- 0.01 mg/ml).
• Greatest changes observed in small-molecular-weight proteins (<345,000), with an inverse correlation between molecular weight and concentration increase.
• 3.8-fold increase in radioactive albumin in allergen-exposed airways, indicating increased vascular-epithelial permeability.
• Elevated serum proteins in BAL fluid observed 2-4 hours post-aerosol challenge.

Conclusions:

• Allergen exposure acutely increases bronchovascular permeability to serum proteins in sensitive asthmatics.
• This increased permeability affects proteins across a range of molecular weights.
• The findings suggest a significant role for vascular leakage in the immediate asthmatic response.