Asthma and its treatments to prevent airway obstruction. Representation of the lungs with the bronchial tree from which 3 zooms. In the upper left, a healthy bronchiole, below, two asthmatic bronchioles. An allergen (green star) triggers the asthma attack by the activation of lymphocytes producing IgE (green Y) leading to degranulation of mast cells (mauve) which release leukotrienes (black beads) and cytokines (blue beads) mediators of inflammation of the mucosa resulting in bronchoconstriction of smooth muscle fibers, hypersecretion of mucus and obstruction of the airways.