Antithyroperoxidase Antibody-Dependent Cytotoxicity in Autoimmune Thyroid Disease

Context: Thyroid antibody-dependent cytotoxicity has been reported in autoimmune thyroid disease (AITD). Indeed, the role of thyroperoxidase (TPO) autoantibodies (aAbs) in complement-mediated damage by binding to TPO expressed on the surface of human thyroid cells was demonstrated, whereas their activity in antibody-dependent cell cytotoxicity (ADCC) is not well established. Objective: The aim of this study was to define the partners involved in antibody and complement-dependent cytotoxicity (CDC) in AITD and characterize which effector cells are involved in cytotoxicity mediated by anti-TPO aAbs using a chromium release assay. Results: The relative capability of anti-TPO aAbs to mediate ADCC using human thyroid cells in culture varies from 11 to 74.5%, depending on the effectors cells used. The human monocyte cell line HL60 gives a better lysis than the THP-1 cell line as effector cells. It seems obvious that the mechanism of ADCC is mediated quite exclusively by FcγRI. Indeed, the two effector cell line...