Allergic rhinitis and polymorphisms of the interleukin 1 gene complex

Abstract

Background: Allergic rhinitis is a chronic inflammatory disease with a genetic background. Inflammatory reactions are regulated by cytokines. Cytokine genes are polymorphic and have been implicated as candidate genes in allergy. Objectives: To study the significance of the interleukin 1 (IL-1) gene complex in allergic rhinitis. Methods: Population-based, cross-sectional study. We studied the polymorphisms of 3 IL-1 gene complex genes, IL1A (+4845G>T), IL1B (-511°C>T), and IL1RN (variable number of tandem repeats; IVS2, 86 bp, duplicates 2 to 5), in patients with allergic rhinitis. The study group consisted of 405 nonasthmatic individuals of whom 56 had allergic rhinitis. Results: The genotype distribution differed significantly in all cytokine genes studied between subjects with and without allergic rhinitis. The difference was mainly due to an increased number of IL1A allele G homozygotes (67.9% vs 43.2%; odds ratio [OR], 2.8; 95% confidence interval [CI], 1.5-5.1), IL1B heterozygotes (72.2% vs 47.4%; OR, 2.8; 95% CI, 1.5-5.3), and IL1RN allele 2 homozygotes (18.5% vs 7.5%; OR, 2.8; 95% CI, 1.3-6.2) in allergic rhinitis. Haplotype analysis revealed a significant difference in the distribution of IL-1 gene complex haplotypes between subjects with and without allergic rhinitis (P = 0.005, 10 df). Conclusions: The IL-1 gene complex polymorphism is strongly associated with allergic rhinitis in nonasthmatic individuals.