T-CELLS AND THYROID AUTOIMMUNITY

Autoimmune thyroid disease is the archetype of organ-specific autoimmu ne disorders and shares with them T cell dependence. The observation t hat thyroid cells in autoimmune thyroid disease express the major hist ocompatibility complex molecule HLA-DR led to the hypothesis that they could present antigen and initiate or maintain the autoimmune process . However, functional experiments, and recent evidence indicating that provision of a co-stimulatory signal is also essential for efficient antigen presentation, argue against such a role. The analysis of T cel l responses to two major thyroid antigens, thyroid peroxidase and the thyroid stimulating hormone receptor, reveals a heterogeneity both wit hin and between patients, and intrathyroidal T cells show diverse usag e of T cell receptor genes. Therefore, any strategy that uses modified peptides, monoclonal antibodies against specific T cell, receptor mol ecules, or T cell vaccination for the purpose of treating thyroid auto immunity is unlikely to succeed.