Association of Interleukin-12B Polymorphism and Serum Level of Interleukin-12 in a Sample of Egyptian Patients with Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is one of the common autoimmune diseases, which affected by genetic and environmental factors. IL-12 is important cytokine that play an effective role in the inflammatory reaction of RA. It regulates the balance between Th1 and Th2 cells. Gene polymorphism of cytokines may predispose to susceptibility and severity of RA. To assess the association between single nucleotide polymorphism (SNP) in IL-12B gene (rs3212227 A/C) and serum level of IL-12 with the development and or activity of RA disease in Egyptian population. Sixty RA patients and thirty healthy individuals were studied for IL-12B gene (rs3212227 A/C) polymorphism using PCR-RFLP. Serum level of IL-12 was measured by ELISA. The frequency of genotype AC, CC, AC+CC and C allele were significantly higher in patients compared to control group (P < 0.02, 0.007, 0.02) respectively. Serum level of IL-12 was significantly higher in patients compared to control (P < 0.000). Patients who carry AC+CC genotypes had significantly higher DAS28, RF, ACCP and IL-12 compared to AA genotype patients (P < 0.05, 0.000, 0.000, 0.000) respectively. RA patients who carry AC, CC genotypes had more positive inflammatory markers (RF, ACCP) with P < 0.000, 0.05 respectively. Significant positive correlation was found between serum IL-12 and number of swollen joints, RF and ACCP. Present findings suggest that IL-12B gene (rs3212227 A/C) may be associated with development and activity of RA and that serum IL-12 can be used as predictor of activity of the disease.

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