INCREASED SERUM CONCENTRATION OF INTERLEUKIN-5 IN PATIENTS WITH GRAVES-DISEASE AND HASHIMOTOS-THYROIDITIS

We investigated serum levels of interleukin-5 (IL-5) in order to exami ne the role of T-helper 2 (Th2)-type immune response in the pathogenes is of autoimmune thyroid diseases. Serum levels of IL-5 were determine d by a highly sensitive sandwich enzyme-linked immunosorbent assay in 42 patients with Graves' disease, 32 patients with Hashimoto's thyroid itis, 12 patients with silent thyroiditis, and 21 normal controls. Com pared with serum levels in normal subjects (5.8 +/- 4.2 pg/mL), IL-5 w as increased in patients with Graves' disease (16.4 +/- 16.7 pg/mL, p < .01), and in patients with Hashimoto's thyroiditis (10.0 +/- 7.6 pg/ mL, p < .05), but not in patients with silent thyroiditis. There was n o correlation between serum free thyroxine (FT4) and IL-5 levels. Thes e data suggest an important role of the Th2-type immune response in th e pathogenesis of Graves' disease and Hashimoto's thyroiditis.