1. We wish to avoid enrolling subjects, especially children, who have common respiratory problems (aeroallergen sensitivity, asthma, gastric esophageal reflux) that are not associated with an underlying abnormality in host defenses. Evidence of significance of chronic or recurring infections suggestive of an underlying airway surface or systemic host defense defect should be documented by one or more of the following: a) sinus or lower airway cultures positive for bacterial, fungal, or mycobacterial pathogens characteristic of these defects; or b) radiographic evidence of sinusitis with mucosal thickening and/or air-fluid levels; or c) radiographic evidence of bronchiectasis; d) severity of otitis media requiring placement of tympanic membrane pressure equalization tubes; e) severity of sinusitis requiring surgical intervention.