Thyroid Peroxidase and the “Microsomal Antigen” Cannot be Distinguished by Immunofluorescence on Cultured Thyroid Cells

Abstract

Recent evidence indicates that human thyroid peroxidase (TPO) shares most of the characteristics of the thyroid microsomal autoantigen (MAg)(1, 2). The question of whether TPO accounts for a part or all the antigenic activity recognized by circulating anti-MAg autoantibody (anti-MAb) is still unsolved. Using an indirect immunofluorescence technique MAg can be identified in the cytoplasm and on the surface of human thyroid cells (3). More recently we have shown that in the differentiated rat thyroid cell strain FRTL-5 the expression of MAg is modulated by TSH added in the culture medium (4). In this study a four-layer IFL technique was applied to human thyroid cells in primary culture in order to obtain a simultaneous staining of the antigen (s) recognized by autoimmune sera containing anti-MAb and by a monoclonal anti-TPO antibody (1). Experiments were performed with cells cultured in the presence or in the absence of TSH.