Asthma is the most common childhood disease. It is characterized by inflammation of the small airways of the lung that produces intermittent narrowing of the respiratory bronchioles, airflow limitation, and the symptoms of wheezing, chest tightness, and breathless ness. The most common form is allergic asthma, also known as atopic asthma. The atopic state is distinguished by the strength of the immunoglobulin E (IgE) response to commonly inhaled proteins, known as allergens.