TF Leung, IHS Chan, GWK Wong, NLS Tang, SL Ma, CWK Lam, TF Fok, PC Ng

Abstract

Interleukin (IL)-1 gene family encodes for pleiotropic pro-inflammatory and anti-inflammatory cytokines. Genome screens mapped asthma phenotypes to chromosome 2q12-21 where IL-1 gene cluster is located. This study investigated the relation between asthma traits and polymorphisms at positions -31 and -511 of IL-1β gene (IL1B) in Chinese children. Plasma total IgE and allergen-specific IgE concentrations were measured by immunoassays. IL1B promoter genotypes were characterised by restriction fragment length polymorphism. One hundred and fifty-eight patients and 56 controls were recruited. Significant inter-ethnic variations in allele frequencies of IL1B were found between Chinese and other populations. Neither IL1B polymorphisms was associated with asthma. However, patients homozygous for IL1B -31C had lower FEV₁ (p=0.03) and FVC (p=0.008). More subjects with IL1B -31C/-511T haplotype had increased plasma total IgE (OR 1.61, 95%CI 1.02-2.54; p=0.04) and decreased FEV₁ (OR 1.78, 95%CI 1.06-3.02; p=0.03) and FVC (OR 1.87, 95%CI 1.09-3.22; p=0.02). In conclusion, IL1B promoter polymorphisms are associated with poorer lung function and increased plasma total IgE concentration in Chinese children.