Name: Thyroid Peroxidase Antibody (Clone EP159)
Description and applications:Thyroid peroxidase (TPO) is a type I glycosylated protein located in the apical membrane of thyroid follicular cells. Its secretion is controlled by the TPO gene, located in the chromosomal region 2p25.3. Under normal conditions, it plays an important role in the synthesis of thyroid hormones by catalysing iodine oxidation and binding to tyrosine residues to form iodotyrosine. It also regulates the binding of iodotyrosine residues for the formation of active hormonal elements such as thyroxine (T4) and triiodothyronine (T3). Mutations in the TPO gene are responsible for type 2A thyroid dysmorphogenesis (TDH2A), manifested primarily with congenital hypothyroidism. According to studies of its mRNA, the expression of TPO isreduced in thyroid carcinomas and has normal levels in non-secreting adenomas (cold). Likewise, high levels of TPO have been detected in toxic adenomas and in Graves’ disease. As TPO reflects the thyroid gland normal function and, therefore, it should not be expressed in malignant lesions, its presence in the cytoplasm of tumour thyreocytes has been explored in the difficult differential diagnosis between follicular and papillary thyroid carcinomas. Depending on the series of studies considered, TPO functions as a negative marker for the diagnosis of malignant thyroid lesions, with a variable sensitivity between 44% and 100% and a specificity ranging from 68% to 100%. Likewise, loss of TPO expression is more specific for papillary carcinomas than for follicular carcinomas, although expression loss in malignant lesions is variable and there is no generally accepted consensus regarding the percentage of negative cells needed to support the diagnosis of malignancy. For this reason, TPO expression should always be assessed in conjunction with other markers and be supported by the morphological changes observed in the lesion. Studies in the literature indicate that anti-TPO, together with antibodies against HBME-1, galectin-3, and cytokeratin 19, may be included in an immunohistochemical marker panel for the identification of papillary thyroid carcinoma and some of the follicular variants of this neoplasm. Finally, the sustained expression of TPO in morphologically malignant lesions has been considered as a possible positive prognostic factor since it suggests conserved thyroid function.
Composition: Anti-human Thyroid Peroxidase rabbit monoclonal antibody purified from serum and prepared in 10mM PBS, pH 7.4, with 0.2% BSA and 0.09% sodium azide.
Immunogen: Synthetic peptide corresponding to Cterminal residues from human protein TPO.