Symposium on allergic lung disease. II. The late asthmatic responses.

Immediate asthmatic responses have been regarded as the characteristic type of asthmatic response to follow exposure to inhaled allergens in patients with extrinsic asthma. They begin within minutes, clear within one to three hours and are inhibited by disodium cromoglycate but not by corticosteroids. They involve the reaction of antigen with antibodies usually of the IgE class. In recent years allergen inhalation tests have demonstrated the frequent occurrence of late asthmatic responses, either following immediate responses (dual responses) or occurring in isolation. The late asthmatic responses begin two to six hours after the allergen challenge, are prolonged and often severe, and are inhibited by both disodium cromoglycate and corticosteroids. The mechanisms involved in their provocation are not clearly understood but from the allergic viewpoint they may involve the participation of IgG +/- IgM antibodies and/or IgE antibodies. Late asthmatic responses explain the frequent occurrence of allergen-induced prolonged asthma. Their features suggest that they are more important than immediate responses in the pathophysiology of asthma.