allergic asthma, a form of asthma caused by exposure of the bronchial mucosa to an inhaled airborne antigen. The antigen causes the production of antibodies that bind to mast cells in the bronchial tree. The mast cells then release histamine, which stimulates contraction of bronchial smooth muscle and causes mucosal edema. Hyposensitization treatments are more effective for pollen sensitivity than for allergies to house dust, animal dander, mold, and insects. Psychological factors may provoke asthma attacks in bronchi already sensitized by antigens. Medication, including immunotherapy, can help relieve allergy symptoms. Often a diurnal pattern of histamine release occurs, causing variable degrees of bronchospasm at different times of the day. Also called atopic asthma, extrinsic asthma. See also asthma, asthma in children, asthmatic eosinophilia, status asthmaticus.