By American Thoracic Society, [RxPG] Researchers have discovered a new way to distinguish virus-induced asthma from that of allergen-caused disease based on a study of 59 asthma patients who were experiencing an acute exacerbation.
The investigators compared sputum cellular profiles of the 59 acute asthmatics against those of 45 controls. The control groups included 14 patients with stable asthma and no viral infection, 15 subjects without asthma but with a viral infection, and 16 healthy, uninfected persons. To establish infection status along with pulmonary status/history, participants completed common cold and asthma questionnaires, microbiological tests, and lung function and allergy (atopy) tests.
A respiratory virus was detected in 46 subjects, or 78 percent, of those with acute asthma.
In both children and adults, asthma exacerbations are caused by viral respiratory infections. Eighty three percent of the cases were infected with rhinovirus.
Expression of interleuken 10 (IL-10), a potent immunoregulator that functions to suppress immune responses broadly, was significantly increased in acute asthma with viral infections when compared with the control groups. Upon recovery from acute asthma, IL-10 gene expression returned to normal levels.
Consequently, according to the authors, IL-10 gene expression from airway cells appears to be a feature of virus-induced acute asthma. They said that their results reveal different mechanisms at work in virus-induced asthma patients than those described in allergen-induced asthma.
Publication:
The study appears in the second issue for August 2005 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.
On the web:American Thoracic Society
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