Interference of thyroperoxidase on immuno-cytochemical determination of steroid receptors in thyroid tissue

Abstract

The presence of sexual steroid receptor proteins in thyroid tissue has been previously demonstrated by biochemical means. The aim of this study was to determine the estrogen (ER) and progesterone (PR) receptors in malignant (12 papillary and 1 follicular carcinoma) and nonmalignant (19 multinodular goiters, 1 Graves' disease, 1 Hashimoto's thyroiditis) thyroid diseases using immunocytochemical assay employing monoclonal anti-ER and anti-PR antibodies and the peroxidase-antiperoxidase technique. Positive results were obtained in 24/34 (70%) for ER (ER-ICA+) and 22/34 (64%) for PR (PR-ICA+). To evaluate the possible interference of thyroperoxidase in the immunostaining, in consecutive sections of a positive specimen, primary antibody or primary antibody plus bridging antibody or PAP complex was omitted. Using these modified procedures, staining distribution was similar to that obtained by the standard procedure: in contrast, no staining was found in the positive control, i.e. a breast cancer specimen. The inhibition of the endogenous peroxidase caused a loss of staining in both the standard and modified procedures on thyroid specimens; no staining modification was obtained in the positive control. These results suggest that the staining observed in thyroid tissue is not specific and related to the activity of thyroperoxidase on chromogen solution. The complete loss of staining after peroxidase inhibition appears to be in contrast with the results obtained by biochemical method, and different antigenicity of thyroid receptors in comparison with breast receptors may explain this discrepancy.

Effect of Conjugated Equine Estrogens and Tamoxifen Administration on Thyroid Gland Histomorphology of the Rat

“…The presence of estrogen receptors in the thyroid suggests a direct action of estrogens and estrogenic-stimulating drugs on the gland. [23][24][25] Also, some experiments using thyrocytes in vitro have demonstrated that estrogen has a definite role in the proliferation of these cells. 5,6,26,27 However, some studies have shown that the effects of estrogen and tamoxifen on thyroid gland may be rather indirect, as a consequence of increased serum levels of thyroxine-binding globulin (TBG) and the associated changes in thyroid function.…”

Thyroid function in postmenopausal breast cancer patients treated with tamoxifen

“…The observed increase in TG suggests a reduced liberation of T4 during the secretory process of thyroid hormones, which could be the mechanism behind the reduction in plasma FT4 and FT3. Thyroid tissue is known to express the oestrogen receptor [15]. Because an increase in TG also is seen during pregnancy, the observed elevation of TG in plasma may represent an oestrogen-agonistic effect of tamoxifen [16].…”

In situ immunoradiographic method for quantification of specific proteins in normal and ischemic brain regions

“…These events can confound the specificity of immunoreactive signal and can lead to increased unspecific antibody binding (Larsson, 1988). The endogenously produced peroxidase, an important factor in pathogenesis of ischemic tissue damage (Bazan et al, 1995;Hall et al, 1993;Kinuta et al, 1989;Sakamoto et al, 1991) and part of the repair mechanisms after ischemia (Takizawa et al, 1994), confounds the correlation of enzyme activity to bound antibody using the immunoperoxidase method (Giani et al, 1993). Although methods to inactivate peroxidase are available (Larsson, 1988;Malorny et al, 1988), these approaches are not always used and if used, the effectiveness and completeness of the inactivation is not assessed routinely.…”