The role of IL15 gene variants in visceral leishmaniasis among Iranian patients

The role of IL-15 in the protection against Leishmania (L) parasites has been clarified in previous studies, in which IL-15 similar to IFN-γ induces IL-12 production and stimulates the leishmaniacidal activity of the macrophages infected with L. infantum. Furthermore, the increased level of IL-15 in acute visceral leishmaniasis patients (VL) can suppress Th2 cytokines such as IL-4. Since different single nucleotide polymorphisms (SNPs) in the IL15 gene have been described, this study aimed to investigate the association of the SNPs at the positions 267, 367, 13,687 and 14,035 with VL. The IL15 gene variants were compared between two groups consisting of 117 VL patients and 146 healthy individuals using polymerase chain reaction-restriction fragment length polymorphism. The results showed that the frequencies of the alleles 267C (83.9 vs. 73.5 %, P = 0.0035), 13687A (22.4 vs. 12.8 %, P = 0.032), genotype 267CC (68.5 vs. 55.6 %, P = 0.031), haplotypes CGCA (16 vs. 8.3 %, P = 0.02) and TACA (11.2 vs. 4.8 %, P = 0.02) were significantly higher in the controls than those in the patients, while the genotypes 267TT (8.5 vs. 0.7 %, P = 0.0016), 13687CC (78.6 vs. 65.5 %, P = 0.015), the haplotypes TGCT (10 vs. 2.5 %, P = 0.00002) and TGCA (5.7 vs. 0.35 %, P = 0.000001) were significantly more frequent in the patients. In conclusion, it may be speculated that these gene variants with probable effects on the IL-15 production can serve as the factors influencing VL among Iranian population. However, to clarify the association of these variants with the level of IL-15, further studies are recommended.