Effect of propylthiouracil and methimazole on serum cytokines in patients with Graves' disease

Abstract

Sixty-four patients with Graves' diseases were divided into methimazole group ( n =30 ) and propylthiouracil group( n =34 ).20 healthy volunteers were used as the control group.The levels of interleukin (IL) -2,IL-6,and TSH receptor antibody (TRAb) were determined by ELISA after serum samples were eollected before treatment and after treatment for 3 and 6 months.The results showed that the general data of two groups were not significantly different before treatment.IL-2 and IL-6 levels at 6 months after treatment were significantly different from the baseline (P＜ 0.05 ),IL-2 being gradually increased while IL-6 decreased with time.The level of IL-6 in methimazole group was lower than that in propylthiouracil group after treatment for 6 months ( P＜ 0.05 ).There was no significant difference in TRAb levels between two groups before treatment while differences became significant at 3 and 6 months of treatment ( all P＜ 0.01 ),being gradually decreased with time. IL-2/IL-6 ratio became significantly greater at 3 and 6 months of treatment compared with that before treatment in the same treatment group( P＜0.05 ) and the ratio in methimazole group was higher than that in propylthiouracil group by 6 months of treatment ( P＜0.05 ).IL-6level was positively correlated with FT3 and FT4 levels,and IL-2 level was negatively correlated with FT3,FT4,and TRAb levels in GD patients before treatment.The correlations of IL-2 and IL-6 with FT3 and FT4 disappeared by 3 and 6 months of treatment.IL-2 and IL-6 levels were related with TRAb level before and after treatment in methimazole group. These results suggest that the immunosuppressive effect of methimazole is more evident than that of propylthiouracil in patients with Graves' disease. Key words: Methimazole; Propylthiouracil; Graves' disease; Cytokines