IL-10 -592A/C polymorphism is associated with severity of Hashimoto's disease

The genetic producibilities of T helper type 1 (Th1) and T helper type 2 (Th2) cytokines are associated with the prognosis of autoimmune thyroid diseases (AITDs). Interleukin (IL)-10 is considered to be a Th2 cytokine that can exhibit an anti-inflammatory role. Furthermore, IL-10 may be associated with the development of IgG4-related diseases, because IL-10 promotes IgG4 production by B cells. To evaluate the relationship between the functional -592 A/C polymorphism in the gene encoding IL-10 and the prognosis of AITDs, we genotyped this polymorphism in 57 patients with intractable GD, 43 patients with GD in remission, 63 patients with severe HD, 44 patients with untreated mild HD, and 62 healthy volunteers by the direct sequencing method. The CC genotype, which is associated with higher producibility of IL-10, was more frequent in patients with severe HD than in those with mild HD (p=0.0201). However, there were no significant differences in serum IgG4 levels between these two groups of HD patients or among 3 genotypes of this polymorphism. There were no significant differences in genotype and allele frequencies between the two GD groups, or between the controls and AITD patients. These data indicate that the functional -592 A/C polymorphism in the IL10 gene is associated with the severity of HD but not with serum IgG4 levels.