Abstract
Objectives: To assess serum interleukin (IL) 13 levels in atopic diseases and to determine the role of IL-13R A(1) gene polymorphism (+ 1398 A/G) in pathogenesis of these diseases. Methods: Serum total immunoglobulin (Ig) E and IL-13 levels were measured by ELISA and the IL-13R A(1) gene (+ 1398 A/G) was screened by PCR-restriction fragment length polymorphism (RFLP) in 240 asthmatic children (120 atopic and 120 nonatopic) and 120 allergic rhinitis patients compared with 120 age-matched controls. Results: No significant association was observed between genotype frequencies of the IL-13R A(1) + 1398 A/G polymorphism in patients groups compared to in controls. There was a significant increase in serum levels of total IgE & IL-13 towards heterozygous AG and homozygous GG than homozygous AA in atopic asthma, non-atopic asthma and allergic rhinitis groups (P < 0.001 for each). A highly significant increase of serum IL-13 in atopic asthma as compared with controls (P < 0.001) and with nonatopic asthmatics (P < 0.001) was shown. Conclusion: The IL-13R A(1) + 1398 A/G polymorphism does not contribute to asthma or allergic rhinitis susceptibility, yet serum IL-13 can be used as a marker in atopic diseases and to differentiate between atopic and non-atopic asthma.