Polymorphisms of interleukin-31 are associated with anti-CCP levels in females with rheumatoid arthritis

Cytokines play important roles in a wide range of different cell types, tissues and organs. Interleukin-31 (IL-31) is a member of the IL-6 family of cytokines. IL-31 is a T helper type 2 (Th2) effecter cytokine that plays an important role in atopic and allergic diseases. It was found that geno-type and allele frequencies of the IL-31 SNPs in rheumatoid arthritis (RA) patients were not signicantly different from those in the healthy controls. The haplotype frequencies of IL-31 SNPs were also not signicantly different between the RA patients and the healthy controls. Theg.-1066G>A, g.586C>A and g.1449C>G polymorphisms of IL-31 were signicantly associated with the anti-CCP levels in the female RA patients (P = 0.010, 0.012 and 0.025, respectively). The results indicate that in RA patients, IL-31 SNPs may play a role in anti-CCP production, and suggest that SNPs in the IL-31 gene could be associated with susceptibility to RA.