Background
Graves’ disease (GD) is an autoimmune thyroid disease which has sophisticated pathogenesis and therefore difficult to achieve complete remission. Interleukin-12 (IL-12) is the main cytokine produced by the Antigen Presenting Cell (APC) and plays an important role in the pathogenesis of GD. Treatment of GD using Methimazole (MMI) known to reduce freeT4 (fT4) level and give a suppression effect to the immune system. Even though, correlation between alteration of fT4 and IL-12 level during MMI therapy remains unclear.
Method
This is a prospective cohort study. Thirty three patients aged 16-60 years with GD were evaluate for their fT4 (enzyme-immunoassay method) and IL-12 level (ELISA method) serially during 2 month therapy of MMI. Differentiation among and between serial level of fT4 and IL-12 were done using Friedman and Wilcoxon signed rank test. Correlation between delta of fT4 and IL-12 level done using Rank-Spearmen correlation test. Statistical analysis using SPSS 16.0.
Result
Respondents: 12 males, 21 females. Median of age 36(16-60) years old. All respondents were in thyrotoxic condition (mean score of Wayne index: 21,4±7,4). Serial median level of fT4 during treatment were 2,77(1,60-7,77), 1,34(0,61-7,77), 1,04(0,40-5,00) ng/dL respectively; p=0,00;95%CI. Serial median level of IL-12 during treatment were: 167,8(56,1-556,6), 200,9(54,5-521,8), 176,0(55,3-480,3) pg/mL respectively; p=0,023;95%CI. Alteration of fT4 level showed a weak correlation with the alteration of IL-12 level (p=0,007-0,048;rho=0,346-0,459;95%CI) in patients with GD receiving MMI therapy.
Discussion
Two month period of MMI therapy normalized thyroid function significantly but weakly reduced the immunological state. Reduction of fT4 level occurred as soon as MMI administered, whereas reduction of IL-12 occurred slowly and unstable. Suppression of immunity in GD need much longer time since many factors might affect the synthesis of IL-12 from the APC.
Conclusio
Thyroid function has a weak correlation with immunological state in GD patient receiving 2 month MMI therapy.