Allergen‐induced increase in non‐allergic bronchial reactivity

Abstract

Summary: Non‐allergic bronchial hyper‐reactivity is a feature of most patients with asthma. We have measured non‐allergic bronchial reactivity to inhaled histamine and methacholine in thirteen asthmatic subjects before and after allergen inhalation in the laboratory. The allergen inhalation produced mild early asthmatic responses (19–40% FEV 1 fall) in all thirteen, additional definite late asthmatic responses (17–29% FEV 1 fall) in four, and equivocal late asthmatic responses (5–11% FEV 1 fall) in five. Following allergen inhalation, non‐allergic bronchial reactivity increased in seven for up to 7 days. The seven included all four with definite late asthmatic responses and three of the five with equivocal late asthmatic responses. We conclude that allergens make asthma worse, partly through non‐allergic mechanisms, and that avoidance of allergens is important in reducing non‐allergic bronchial hyper‐reactivity.