Systemic lupus erythematosus (SLE) is a multisystem autoimmune connective tissue disorder characterized
by loss of self-tolerance causing immune-mediated tissue destruction and various clinical presentations
Interleukin-18 (IL-18) is a proinflammatory cytokine that plays an important role in chronic inflammation and
autoimmune disorders. This study investigates polymorphisms of the IL-18 gene in SLE patients at positions
-607 and -137 of the promoter to elucidate their possible roles in the activity and severity of this disease. Fifty
SLE patients and fifty unrelated healthy control group were included. All SLE patients underwent thorough
clinical examination and SLE disease activity assessment using SLEDAI. Genomic DNA was extracted from
peripheral venous blood. Sequence-specific primer PCR analysis were used to genotype the DNA samples
for SNP-607and SNP-137, while plasma IL-18 concentrations of patients and control subjects were measured
by enzyme-linked immunosorbent assay. The frequency of SNP-607/CC genotype showed significant
increase (P