This is a prospective observational study , to clarity the characteristics of airway inflammation, airway reactivity and airway resistance in rhinitic children with or without asthma and to explore the possible predictors in the progression of allergic rhinitis to asthma.

Children 6-15 years old with allergic rhinitis and/or asthma diagnosed by specialist physician are enrolled in the department of respiratory and otorhinolaryngology and pediatrics in Guangzhou Institute of Respiratory Disease. According to presence of typical symptoms and signs, patients are divided into allergic rhinitis without asthma (AR group) , allergic rhinitis concomitant asthma (AS+AR group), asthma without rhinitis (AS group). In addition, healthy students in a school are enrolled as normal control group. History of all subjects are collected, the following measurements are performed: skin prick test (SPT), peripheral blood cells five-classification test, serum total immunoglobulin E (IgE) and specific IgE of common inhalant allergens testing, nasal lavage and induced sputum cells classification ，pulmonary function test, bronchial provocation test using methacholine，airway resistance measured by impulse oscillation technique, the levels of eosinophil（ECP），eosinophil peroxidase（EPO）.Meanwhile myeloperoxidase （MPO）and eosinophil-derived neurotoxin (EDN) are measured in induced sputum ,in nasal lavage and in serum.

Inclusion Criteria:

• Clinical diagnosis of allergic rhinitis and/or asthma
• Sensitized to more than 1 common aeroallergens

Exclusion Criteria:

• Respiratory infection 2 weeks prior to initial visit
• Children with nasal polyposis
• History of immunotherapy
• Unable to complete the test or had limited understanding
• Use of systemic corticosteroids 4 weeks prior to initial visit
• Nasal and inhaled corticosteroids 2 weeks prior to initial visit
• Leukotriene receptor antagonists 2 weeks prior to initial visit

Children 6-15 years old with allergic rhinitis and/or asthma diagnosed by specialist physician were enrolled in the department of paediatrics,respiratory and otorhinolaryngology in Guangzhou Institue of Respiratory Diseas .In addition, healthy students in a school were enrolled as normal control group.