Endocrine Abstracts

Introduction: Glycoprotein gp91-phox is an essential component of the NADPH oxidase. The superoxide-generating NADPH oxidase is present in phagocytes, neuroepithelial bodies, vascular smooth muscle cells and endothelial cells. It includes a membrane-bound flavocytochrome containing two subunits, gp91-phox and p22-phox. gp91-phox is a significant element of the membrane-bound oxidase of phagocytes that generates superoxide. It is the terminal component of a respiratory chain that transfers single electrons from cytoplasmic NADPH across the plasma membrane to molecular oxygen on the exterior. This glycoprotein participates in the regulation of cellular pH and is blocked by zinc. gp91-phox could be potentially useful in diagnosis of primary hyperparathyroidism which is one of the most common endocrine disorders caused by adenoma (80%), hyperplasia (15%) and carcinoma (5%).

Methods: For immunohistochemistry, parathyroid specimens of patients undertaken surgery due to primary hyperparathyroidism caused by adenoma and primary hyperplasia were investigated. Normal healthy tissues served as a control. Frozen sections were incubated with purified mouse monoclonal antihuman antibodies anti-gp91-phox. The dilution of the primary antibodies was 1:50 and was verified in a series of pilot experiments. The immunohistological investigations were performed by the BrightVision method from ImmunoLogic. The sections were counterstained with Mayer’s haematoxylin. The number of positively stained cells were counted and expressed as a mean value of at least 10 high power fields (400×).

Results: Positive gp91-phox immunoreaction was significantly increased in parathyroid adenomas, whereas gp91-phox was up-regulated in parathyroid hyperplasias compared to healthy parathyroid glands. Positively stained cells were localized in the well vascularized region of the parathyroid nodule.

Conclusions: The immunohistochemical assessment of gp91-phox complements conventional methods in distinguishing between parathyroid hyperplasia and adenoma, however, there is an overlap between these parathyroid lesions and there is no definite cutoff value.