Isolated airways from current smokers are hyper-responsive to histamine.

Area of Science:

• Pulmonary Medicine
• Immunology
• Respiratory Physiology

Background:

• Epidemiological studies link current smoking to increased bronchial hyper-responsiveness (BHR) and elevated serum IgE.
• Elevated serum IgE is known to be associated with BHR.
• The independent effect of smoking on BHR, separate from IgE, requires investigation.

Purpose of the Study:

• To determine if smoking impacts BHR independently of immunoglobulin E (IgE) levels.
• To investigate the combined effects of smoking and IgE on airway responsiveness.

Main Methods:

• Isolated peripheral airways from current smokers and non-smokers with low serum IgE were used.
• Airway rings were incubated with or without serum containing high IgE levels (passive sensitization).
• Isometric contractile responses to histamine were measured in an organ bath.

Main Results:

• Airways from current smokers demonstrated significantly increased contractile responses to histamine compared to non-smokers.
• Passive sensitization with IgE-containing serum significantly enhanced histamine responses in both smokers and non-smokers.
• The enhancing effect of passive sensitization was similar between the two groups.

Conclusions:

• Current smoking is associated with increased in vitro bronchial responsiveness to histamine, even in individuals with low baseline serum IgE.
• Both smoking and serum IgE independently contribute to non-specific airway hyper-responsiveness.
• These findings highlight the complex interplay between smoking and immune factors in respiratory health.