NEW YORK (Reuters Health) - Phenotypic differences exist between early-onset, severe asthma and late-onset disease. Moreover, these phenotypes seem to be influenced by the presence or absence of eosinophilia, researchers report in the January issue of The Journal of Allergy and Clinical Immunology.
“Asthma has traditionally been very broadly defined in terms of symptoms rather than underlying biological processes,” senior author Dr. Sally E. Wenzel, from the National Jewish Medical and Research Center in Denver, said in a statement.
The current research helps divide “severe asthma patients into four subsets, based on age of onset and presence or absence of eosinophils,” Dr. Wenzel noted. “We believe these subsets represent different biological processes and mechanisms of steroid resistance.”
The study involved 80 patients with severe asthma. Asthma onset was defined as early or late based on whether symptoms began before or after the age of 12 years.
Early-onset asthma was tied to greater allergen sensitivity and more allergic symptoms than late-onset disease. In contrast, late-onset disease was associated with lower lung function than early-onset disease.
In both onset groups, the presence of eosinophils was tied to more asthma symptoms and lower lung function than the absence of such cells.
The greatest amount of eosinophilia was seen with late-onset disease, whereas a lymphocytic/mast cell inflammatory process was seen only with early-onset disease. Patients with late-onset disease lacking eosinophilia also showed “no subepithelial basement membrane thickening, suggesting,” say the researchers, “a different pathologic process.”
They conclude that “differentiating asthma on the basis of onset of disease and presence of eosinophilia should enhance our ability to isolate genetic differences, understand pathophysiology, and ultimately improve approaches to therapy.”
Source: J Allergy Clin Immunol 2004;113:101-108. [ Google search on this article ]
Copyright © 2002 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.
