Interleukin-4 polymorphism is associated with severity of respiratory syncytial virus infection

Aim: Respiratory syncytial virus (RSV) infection is a major health problem in young children. This study aimed to investigate whether the interleukin (IL)-4-590C/T and -33 C/T polymorphisms were associated with the susceptibility to RSV infection in Chinese Han children and with the severity of the infection. Methods: The IL-4 -590C/T and -33 C/T SNPs were evaluated in 218 inpatients with RSV bronchiolitis and 303 healthy controls. The severity of RSV bronchiolitis was evaluated using a respiratory scoring system. Results: The frequencies of IL-4 -590 CC, CT and TT in the 218 RSV bronchiolitis patients versus the 303 controls were 1.4% versus 1.7%, 21.1% versus 34% and 77.5% versus 64.4%, respectively. The frequencies of IL-4 -33 CC, CT and TT were 1.4%, 20.6% and 78%, respectively, in RSV bronchiolitis patients and 2.3%, 35.6% and 62%, respectively, in the controls. The frequencies of the IL-4 -590C/T and -33 C/T polymorphisms were significantly different between the two groups. There was a significant difference in the frequency of the T-T haplotype formed by -590C/T and -33C/T between the two groups. The respiratory score of the RSV bronchiolitis cases with -590TT was 3.02 +/- 0.44, which was significantly higher than those with -590CT (2.80 +/- 0.44). The score for patients with -33TT was 3.03 +/- 0.43, which was significantly higher than the score of 2.78 +/- 0.46 for patients with -33CT. Conclusions: In Chinese Han children, the IL-4 -590C/T and -33 C/T polymorphisms were associated with the susceptibility to RSV and the severity of the infection.