INTRODUCTION: Interleukin 18 (IL-18), which is an important interferon γ inducer, regulates the expression of the proinflammatory cytokine interferon γ and the antituberculosis response.
OBJECTIVE: Our goal was to investigate polymorphisms of the IL-18 gene promoter and determine whether polymorphism of the IL-18 gene promoter is a potential host-susceptibility factor in tuberculosis in Chongqing, China.
METHODS: A total of 123 patients (including 91 children and 32 adults) with tuberculosis and 249 normal controls (including 167 children and 82 adults) were selected randomly. The polymorphisms at positions -607A/C and -137G/C in promoter of the IL-18 gene were analyzed by using polymerase chain reaction with sequence-specific primers.
RESULTS: The allele and genotype frequencies of IL-18/-607 gene polymorphisms were similar in patients with tuberculosis and in controls. However, frequencies of the -137GG, GC, and CC genotypes were 67.9%, 28.5%, and 3.6%, respectively, in controls and 78.9%, 19.5%, and 1.6%, respectively, in those with tuberculosis. Frequency of the -137GG genotype in tuberculosis was significantly higher than that in controls (χ2 = 4.881; P = .027 < .05). The frequency of allele G at position -137 in patients with severe tuberculosis was significantly higher than that in patients with pulmonary tuberculosis (χ2 = 4.336; P = .037 < .05).
CONCLUSIONS: Polymorphism of the IL-18 gene promoter at position -137 is a potential host-susceptibility factor in tuberculosis in Chongqing. The people with allele C at position -137 in the promoter of the IL-18 gene may be protected against mycobacterium tuberculosis infection. The polymorphisms at position -137 of the IL-18 gene may be associated with a severe degree of tuberculosis.
Submitted by Li-Ping Jiang
- Copyright © 2008 by the American Academy of Pediatrics