Molecular Cloning and Partial Characterization of a New Autoimmune Thyroid Disease-Related Antigen*

To clone and characterize antigens to autoantibodies in Hashimoto’s thyroiditis we constructed a cDNA library in the expression vector λgtll using mRNA prepared from Graves’ thyroid tissue. This library was screened using serum from a patient with Hashimoto’s thyroiditis which had an antimicrosomal antibody titer greater than 1:106. Five positive recombinants were identified and cloned. Of these, 3 reacted with 7 of 17 normal serum samples. The 2 other clones (IL-28 and IL-33) reacted with none of the 17 normal serum samples. IL- 28 reacted with 4 of 15 and IL-33 with 2 of 15 Hashimoto’s thyroiditis serum samples (antimicrosomal antibody titers, >1:6400). The specificity of the interaction between the Hashimoto’s thyroiditis samples and the fusion protein was demonstrated by Western blot analysis. In addition, neither 10−6 M human thyroglobulin nor 100 mU/mL bovine TSH inhibited binding of the serum samples to these 2 clones. Lysate from clones IL-28 and IL-33 did not reduce the antimicrosomal antibody ti...