This study investigated serum levels of the soluble form of CD30 (sCD30), which is mainly secreted from T helper 2(Th2) cells, in autoimmune
thyroid diseases. The possible relationship of sCD30 to
autoantibody production was also evaluated. Serum levels of sCD30 were determined by an
enzyme-linked
immunosorbent assay in 71 patients with
Graves' disease, 37 patients with Hashimoto's
thyroiditis, and 21 normal donors. Compared with normal subjects (7.1 +/- 4.5 U/mL), sCD30 was increased in patients with
Graves' disease (29.2 +/- 25.2 U/mL, P < 0.0001) and in patients with Hashimoto's
thyroiditis (29.9 +/- 26.9 U/mL, P < 0.0001). In
Graves' disease, sCD30 levels were higher in thyrotoxic patients (41.7 +/- 31.2 U/mL, P < 0.001) than in remission patients (15.8 +/- 11.0 U/mL), and a significant correlation was observed between sCD30 levels and serum activities of
TSH receptor antibody (r = 0.444, P < 0.0001). In Hashimoto's
thyroiditis, sCD30 levels were higher in patients with transient destructive
thyrotoxicosis caused by the aggravation of the disease (48.8 +/- 34.4 U/mL, P < 0.05) than in euthyroid patients (24.2 +/- 19.4 U/mL). These data suggest that serum sCD30 is a valuable marker of disease activity and support an important role of the Th2-type immune response in the pathogenesis in
Graves' disease and Hashimoto's
thyroiditis.