T cell responses to synthetic thyroid peroxidase peptides in autoimmune thyroid disease.

Sixteen peptides, representing four different extracellular regions of thyroid peroxidase (TPO) predicted to contain a high proportion of potential T cell epitopes, were synthesized to investigate which parts of this autoantigen may be targets for the T cell response in thyroid autoimmunity. Compared with 25 controls, peripheral blood T cells from 23-37% of 30 patients with Graves' disease or autoimmune hypothyroidism were stimulated significantly by three peptides, representing amino acids 415-432, 439-457 and 463-481 of the TPO sequence; T cells from individual patients were also stimulated by several other peptides. These results indicate that the T cell response to TPO is directed against several epitopes which may be recognized by different patients.