Objective: To investigate the polymorphism of interleukin (IL)-13 gene in Chinese Han population, and to study the possible association of IL-13 polymorphism and the susceptibility to chronic obstructive pulmonary disease (COPD).
Methods: Using genomic DNA extracted with phenol:chloroform:isoamyl alcohol from the blood of 94 healthy smokers and 88 COPD smokers, three single nucleotide polymorphism (SNP) sites in IL-13 gene marked as 1103C/T, 4257G/A, 4738G/A were determined by polymerase chain reaction/restriction fragment length polymorphism analysis or polymerase chain reaction/single strand conformation analysis. In addition, plasma IL-13 concentration was measured by ELISA on 24 healthy smokers and 24 smokers with chronic obstructive pulmonary disease.
Results: (1) To 4257G/A and 4738G/A SNP sites, the genotype frequencies and allele frequencies were not significantly different between healthy smokers and COPD smokers (P > 0.1). (2) To 1103C/T SNP site, relative higher CC genotype frequency and C allele frequency were found in healthy smokers (P < 0.05), also C allele could prevent smokers from chronic obstructive pulmonary disease, with OR 0.56 and 95% confidence interval was 0.34 - 0.91. (3) Plasma IL-13 concentration was not affected by genotype of 4257G/A or 4738G/A SNP sites. However, 1103CC showed for significantly lower IL-13 concentration in plasma (P < 0.05).
Conclusion: The genotype of IL-13 1103C/T SNP site was associated with the susceptibility to COPD in Chinese Han population and 1103CC accounted for relative lower plasma IL-13 concentration and lower risk for COPD.