Psoriasis is an inflammatory skin disorder that is characterized by a marked proliferation of keratinocytes, vascular dilation and leukocyte infiltration. Cytokines play important roles in the pathogenesis of inflammatory disorders. An overexpression of proinflammatory cytokines was characterized in psoriasis plaque. Among these cytokines, IL-1β is major pro-inflammatory cytokine synthesized during the infection and inflammatory process. The IL-1 receptor antagonist (IL-1Ra) competes for the same IL-1 receptor for IL-1α and -1β, which prevents activation of the target cells. Three single nucleotide polymorphisms (SNPs) in the IL-1β gene have been reported at position -31, -511 and +3954. Within the IL-1Ra gene (IL-1RN), there is a variable number of tandem repeats (VNTR) of an 86 bp length in intron 2. These polymorphisms related to cytokine production and associated with various diseases.

We investigated the polymorphisms of IL-1B (promoter -511 and +3954) and IL-1RN on 114 psoriasis patients and 311 healthy normal controls in Korean. We performed PCR-RFLP on single nucleotide polymorphisms (SNPs) of IL-1B (promoter -511 and +3954) and fragment analysis on IL-1RN 86 bp VNTR polymorphism.

The frequency of IL-1B -511^*1 allele (patients vs. controls; 50.0% vs. 42.3%, RR=1.4) was significantly increased and IL-1B -511^*2 allele (patients vs. controls; 50.0% vs. 57.7%, RR=0.7) decreased in psoriasis patients compared to normal controls. We also analyzed the IL-1B -511 polymorphism according to patients' characters (age of onset, sex and family history). The IL-1B -511 alleles were significantly associated in patients with male and family history than health normal controls. There were no significant associations of IL-1B +3954 and IL-1RN polymorphisms with psoriasis patients.

These results suggest that the polymorphism of IL-1B -511 could be genetic susceptibility to psoriasis in Koreans.