Etiology and Epidemiology of Pediatric Asthma

The susceptibility to allergic disease is determined by a combination of genetics and environment acting through a complex network of cytokines (Fig. 2). It is sustained by an imbalance between two populations of T-helper lymphocytes referred to as Thl and Th2 cells, with the equilibrium shifted toward Th2. Interleukin (IL-4) is pivotal in Th2 ceU development (12) and, together with IL-13, leads to increased IgE production. Both cytokines can upregulate adhesion molecule expression and mucus production in the airways. IL-5 is thought to be 

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All relative standard errors are 30% (i.e., relative confidence interval 59%) unless otherwise indicated. 

Those children who are more likely to have asthma appear to show evidence of an altered immunological process, i.e., they become sensitized to allergens and other antigens early in life. The association among environmental allergens. 

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