Airway reactivity in cotton bract-induced bronchospasm

Area of Science:

• Occupational Health
• Pulmonary Medicine
• Allergy and Immunology

Background:

• Cotton bract extract (CBE) inhalation commonly induces bronchospasm in healthy subjects.
• This bronchospastic response is often linked to histamine production triggered by CBE exposure.
• The underlying mechanisms, particularly histamine sensitivity, require further investigation.

Purpose of the Study:

• To determine if healthy subjects sensitive to CBE exhibit increased sensitivity to histamine.
• To investigate whether heightened histamine reactivity differentiates CBE responders from non-responders.
• To explore potential links between CBE responsiveness and subclinical asthma.

Main Methods:

• Screening of 31 healthy subjects for responsiveness to nebulized CBE.
• Measurement of pulmonary function using partial expiratory flow-volume curves (MEF40%(P)).
• Assessment of histamine dose-response relationships in both CBE responders and non-responders.

Main Results:

• Ten subjects were identified as CBE responders, showing a significant decrease in MEF40%(P).
• No significant difference in histamine sensitivity or threshold dose was found between responders and non-responders.
• The percentage decrease in MEF40%(P) at the histamine threshold was comparable in both groups.

Conclusions:

• Healthy subjects sensitive to CBE do not display heightened reactivity to histamine.
• CBE responsiveness in healthy individuals is unlikely due to increased histamine sensitivity.
• Findings suggest that CBE responders are not typically subclinical asthmatics based on histamine reactivity.