Genetic predisposition to parthenium dermatitis in an Indian cohort due to lower-producing genotypes of interleukin-10 (-) 1082 G>A and (-) 819 C>T loci but no association with interferon-γ (+) 874 A>T locus.

BACKGROUND

Parthenium dermatitis is an activated T cell-mediated type IV hypersensitivity. Its pathogenesis is well characterized, with interindividually varying serum levels of pro- and anti-inflammatory and regulatory T-cell cytokines and coherently perturbed cross-regulation between them. The functional single nucleotide polymorphisms (SNPs) in these cytokine genes might function as risk/susceptibility factors for the disease.

OBJECTIVES

We analysed the serum levels of interferon (IFN)-γ and interleukin (IL)-10 cytokines in cases vs. controls and investigated whether IFN-γ (+) 874 A>T and IL-10 (-) 1082 G > A and (-) 819 C>T are associated with serum levels and genetically predispose to the disease.

METHODS

The study included 60 patch test-confirmed patients and 60 age- and sex-matched controls. The serum levels of cytokines were estimated by high-sensitivity enzyme-linked immunosorbent assay kits. SNP genotyping was performed by amplification refractory mutational system-polymerase chain reaction.

RESULTS

In patients, the serum level of IFN-γ was significantly increased and that of IL-10 was significantly decreased, with no difference in IgE concentration. Genetically no IFN-γ (+) 874 A>T alleles/genotypes were associated with the disease, but a strong predisposition was found due to lower-producing genotypes of IL-10 (-) 1082 G>A and (-) 819 C>T SNPs, with 2·1 and 3·5 times more risk, respectively, while intermediate IL-10-producing genotypes provided resistance.

CONCLUSIONS

High serum IFN-γ might play a role in disease pathogenesis, but this is genetically not endowed by the IFN-γ SNP studied. In contrast, low serum IL-10 was very much connected, with the genetics of both studied IL-10 loci. These might be key managing factors concerning pathogenesis/susceptibility.