Cytokine Gene Polymorphism in BCG Lymphadenopathy

Background: Tumor necrosis factor-beta or lymphotoxin-alpha (LT-α), IL-4 and IL-10 are determining factors in immunity against BCG. Allelic polymorphisms in the regulatory regions of their genes affect the rate of cytokine production and therefore, the host’s ability in BCG containment. Objective: To study the prevalence of –590 (C/T) and –592 (C/A) allelic distribution of IL-4 and IL-10 promoter regions, respectively, and +282 (G/A) polymorphism in the first intron of LT-α in BCG vaccinees with lymphadenopathy comparing to those of controls. Methods: Polymorphisms in the promoter region of IL-4 and IL-10 were determined by primer induced restriction site PCR and the polymorphism in the first intron of LT-α was investigated using PCR-RFLP method. Forty patients with BCG adenitis and 42 healthy age-matched infants without reactions were included in this study. Results: No significant differences existed between allele and genotype frequencies of IL-4 or LT-α genes from patients as compared to the controls. A significant difference in genotype distribution of the IL-10 –592 C-to-T polymorphism was observed between patients and controls (p<0.05). In this respect, the AA and AC genotypes with lower ability in IL-10 production were found more frequently in the control group. Conclusion: The lower frequency of AA genotype at position –592 of IL-10 promoter region in patients may have resulted in more IL- 10 production leading to weaker immune response that allows bacterial burden and occurrence of lymphadenitis