POLYMORPHISM OF TUMOR NECROSIS FACTOR- ALPHA PROMOTER REGION IN IRANIAN VACCINEES WITH BCG ADENITIS

Background: Tumor necrosis factor-alpha (TNF-a) is a determining factor in macrophage activation and direction of immunologic mechanisms to BCG. By regulating the rate of transcription, allelic polymorphism in the regulatory regions of TNF-a gene can affect the host's ability in BCG containment. Objective: To study the prevalence of G to A transition polymorphism at position -308 of the TNF-a gene in Iranian BCG vaccinees with lymphadenitis. Methods: In this study, we determined the polymorphism at position -308 relative to the transcription initiation site of TNF-a gene in 40 patients with BCG adenitis and 42 healthy age-matched infants without reactions by a method based on allele specific PCR. The results of PCR were confirmed by the SSCP method. Results: The frequency of TNFA2 allele in the patient and the control groups were 0.013 and 0.04, respectively. Statistical analysis showed no significant association of TNF-a promoter polymorphism with susceptibility to BCG adenitis. However, there was a threefold increase in the frequency of TNFA2 allele in the control subjects. Conclusion: We suggest that the lower frequency of TNFA2 allele in patients might have resulted in weaker immune response that allows bacterial burden and occurrence of lymphadenitis.