Detecting Virus-Induced Asthma

Australian researchers have discovered a new way to distinguish virus-induced asthma from that caused by allergens, according to a new study of asthma patients who were experiencing acute exacerbation.

In the study, the sputum cellular profiles of 59 acute asthmatics were compared with those of 45 controls. The controls group included 14 patients with stable asthma and no viral infection, 15 subjects without asthma but with a viral infection, and 16 healthy subjects. To establish infection status and pulmonary history, participants completed common cold and asthma questionnaires, microbiologic tests, and lung function and allergy tests.

A respiratory virus was detected in 46 subjects, or 78%, of those with acute asthma. In both children and adults, the asthma exacerbations were caused by viral respiratory infections, with 83% of cases infected with rhinovirus. The researchers found that expression of interleuken 10 (IL-10), which functions to suppress immune responses, was significantly increased in acute asthma patients with viral infections, when compared to control groups. Consequently, IL-10 expression from airway cells appears to be a feature of virus-induced acute asthma. Different mechanisms were found to be at work in virus-induced asthma patients, compared to those described in allergen-induced asthma.

The study, conducted by researchers at the John Hunter Hospital in New Lambton (Australia), appeared in the August 15, 2005, issue of the American Journal of Respiratory and Critical Care Medicine.




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