The balance shift in Th1/Th2 related IL-12/IL-5 cytokines in Graves' disease during methimazole therapy

Abstract

Th1 and Th2-like cytokines are involved in the pathogenesis of Graves' disease. The shift in balance in IL-12/IL-5 cytokines was applied in judging the immunological events in 74 patients with Graves' disease (50 had ophthalmopathy) during methimazole therapy and in 15 controls. The serum levels of IL-12 and IL-5 were measured with enzyme-linked immunosorbent assay in all Graves' patients. Twelve cases for IL-5 and 20 cases for IL-12 were positive. In Graves' patients only those without ophthalmopathy had higher levels of IL-12 when compared to controls (192.66 ± 29.19 vs. 85.09 ± 8.95 pg/ml, P < 0.04). After 2 months of methimazole therapy in Graves' patients without ophthalmopathy an increase in the ratio of IL-12 to IL-5 was also observed as compared to those with eye symptoms (91.78 ± 34.14 vs. 20.72 ± 6.36, P < 0.015). Age-related difference in the serum level of IL-5 could be demonstrated between Graves' patients without and those with ophthalmopathy aged ≤ 35 years (4.89 ± 0.57 vs. 50.14 ± 20.2 pg/ml, P < 0.002). No association was found among the serum levels of IL-5 or IL-12, thyroid hormones and TSH receptor antibodies.The results demonstrated a difference in the balance shift of IL-12/IL-5 between Graves' patients with and without ophthalmopathy. The increased ratio of IL-12 to IL-5 after methimazole therapy could be explained by the elevation of serum IL-12 due to methimazole therapy and the age-related decrease of serum IL-5.