Genetic variations in interleukin-12B in allergic rhinitis.

Interleukin (IL)-12B is a key regulator in the protection against allergic reaction induced by various allergens in patients with allergic rhinitis (AR). This study was performed to investigate the associations between single nucleotide polymorphisms in the IL-12B gene and AR in a Chinese Han population. A total of 543 patients with AR and 600 healthy controls were genotyped for IL-12B/rs6887695, rs10045431, rs3212227, rs3212217, and rs2082412 using polymerase chain reaction (PCR) restriction fragment length polymorphism and PCR direct sequencing. The expression of IL-12B mRNA in peripheral blood mononuclear cells (PBMCs) obtained from normal controls was detected by quantitative real-time PCR. Levels of interferon (IFN)-γ and IL-4 in culture supernatants were measured by enzyme-linked immunosorbent assay. The frequencies of the rs3212227 genotype with the CC and C alleles were higher in patients with AR (p c = 8.55 × 10(-4); p c = 4.20 × 10(-4), respectively) than in normal controls. After peptidoglycan stimulation in PBMCs, IL-12 mRNA expression was reduced in healthy carriers of the CC genotype of rs3212227. Additionally, decreased production of IFN-γ was observed in patients having the CC genotype as compared with that in patients having the AC and AA genotypes. In contrast, IL-4 expression was higher in patients with the CC genotype than in patients with the other two genotypes. The IL-12B gene was involved in mediating susceptibility to AR.