Colocalization of growth hormone (GH) and glycoprotein subunit alpha in GH-producing pituitary adenomas in acromegalic patients.

Thirty-one consecutive cases of pituitary adenoma in acromegalic patients were studied by immunohistochemistry. All adenomas contained cells immunoreactive with the anti-alpha-subunit of gonadotropic hormones (alpha; 0.6-53% of tumor cells) as well as with anti-growth hormone (GH; 4-74% of tumor cells). In serial section study, most cells immunoreactive with anti-alpha were identical to cells immunoreactive with anti-GH. There was a positive correlation between the percentages of cells immunoreactive for alpha in GH cells [alpha (%)/GH(%)] and those for prolactin (PRL) in immunoreactive tumor cells (PRL(%)/[PRL(%) + GH(%)]) in mixed GH cell-PRL cell adenomas, suggesting that the alpha-subunit may play a role in emergence of PRL cells.