Asthma, Normal bronchiole, asthmatic bronchiole with bronchoconstriction, hypersecretion, treatments. Representation of the lungs with the bronchial tree from which 3 zooms depart. Above left, a healthy bronchiole, below, two asthmatic bronchioles. An allergen (green star) triggers the asthma attack by activating lymphocytes producing IgE (green Y) causing the degranulation of mast cells (purple) which release leukotrienes (black beads) and cytokines (blue beads) mediating inflammation of the mucous membrane which leads to bronchoconstriction of smooth muscle fibers, hypersecretion of mucus and obstruction of the respiratory tract.