GAMMA-GLUTAMYL TRANSPEPTIDASE ACTIVITY AND THYROID FUNCTION IN HUMAN THYROID LESIONS

AN ENZYME HISTOCHEMICAL AND IMMUNOHISTOCHEMICAL STUDY

Abstract

A functional aspect of gamma-glutamyl transpeptidase (GGT) activity in human thyroid tissues was immunohistochemically analysed mainly in malignant thyroid neoplasms. Fresh thyroid tissues were removed and fixed in cold acetone and paraffin sections were used for GGT staining (11), and for immune staining for thyroglobulin (T_g), triiodothyronine (T₃) and thyroxine (T₄) with the immunoperoxidase technique. In most sections, double stain (GGT and each immunostain) was performed. A high degree of correlation in positivity between GGT activity and immunoreactivities for T_g and T₃ was demonstrated in well-differentiated adenocarcinomas, whereas both reactions were almost negative in anaplastic and medullary carcinomas. Squamous cell carcinoma showed positive staining for GGT in spite of negligible immuno-reactivities.
Thus, in malignant thyroid neoplasms of follicular cell origin except squamous cell carcinoma, it was concluded that GGT activity was closely related to the immunohistochemically detected functions of follicular epithelium of the thyroid as well as cell proliferation rate (10).