Immunologic mechanisms of virus-induced wheezing and asthma.

Viral infections are a common cause of wheezing at all ages. In addition, it has been suggested that viral infections can induce a long-term asthma diathesis. Because asthma is increasingly understood to be an inflammatory disease, there is great interest in the immunologic mechanisms that may underlie virus-induced wheezing. Viral infections may induce inflammatory responses that closely resemble those characteristic of asthma, including airway infiltration with lymphocytes and eosinophils and release of mediators of airway obstruction. Certain viruses preferentially enhance pre-existing inflammatory responses in atopic individuals. Alternatively, viral infections may induce an altered reactivity favoring the expression of atopy. Finally, immunologic responses to viral infections may serve only as markers of the subsequent development of atopy.