 Secretor status will be studied in order to determine whether it is a risk factor for asthma exacerbations precipitated by viruses. Preliminary studies suggest that secretor positive asthmatics are prone to asthma exacerbations and that asthmatic patients have abnormal glycosidase activity in their airway secretions. This study will explore these findings further in the following two ways: 1 a case-control study will compare secretor status and frequency of viral airway infection in 50 asthmatic patients hospitalized for management of acute severe asthma to 50 asthmatic subjects in the outpatient setting without a history of severe asthma exacerbation. Sputum samples or tracheal aspirates from intubated patients will be collected from all patients. In these samples, DNA will be used as a microarray to detect viruses; and 2 epithelial brushings and bronchial biopsies from a tissue bank will be used to establish the relationship between secretor status erythrocyte Lea and Leb phenotyping and airway epithelial cell activity of FUT genes real time RT-PCR, and expression of Lea, Leb, A, B, and H antigens immunohistochemistry. 