Cytokine single nucleotide polymorphisms in Iranian patients with pulmonary tuberculosis.

Background: Several genes coding for different cytokines may affect host susceptibility to tuberculosis.

Methods: In the present study, the allele and genotype frequencies of a number polymorphic genes coding for cytokines or cytokine receptors were investigated in Iranian patients with pulmonary tuberculosis (PTB).

Results: From the IL-1 cluster, a positive, significant difference was found at position -889, where the T/T genotype was over represented in PTB patients (p = 0.01); a positive, significant increase was found in the IL1R PstI 1970 C/C genotype, where the C allele was over represented in the PTB patients (p = 0.01). A significant negative association at codon 10 TGF-beta, T allele, was shown in our patients and the C allele and C/C genotype were over represented in the PTB patients (P<0.005). For TNF-alpha at position -238, we found a negative association for the G/A genotype and a positive association for the G/G genotype (p = 0.0009). Significant negative associations at position -590 IL-4, T allele and the T/T genotype were shown in our patients (p = 0.0007); also, the C allele and T/C genotype were significantly increased in our patients (P<0.05). With IL-6 at -174, G/G increased and G/C decreased significantly in the patients (P<0.005).

Conclusion: Pro-inflammatory cytokines such as TNF-alpha and TGF-beta seem to be decreased, and IL-6 increased in PTB patients.