Identification of somatotrophs, mammosomatotrophs, and mammotrophs by sandwich cell immunoblot assay in GH-secreting adenomas and prolactinomas: correlations between the proportions of hormone secreting cells and tumor size.

Abstract

Sandwich cell immunoblot assay(sandwich CIBA) was used to identify somatotrophs (GH cells), mammosomatotrophs, and mammotrophs (PRL cells) in pituitary tumors obtained from patients with GH-secreting adenomas and prolactinomas. The mean serum GH level was 177.6 ng/ml in 19 patients with GH-secreting adenomas and the mean PRL level was 2,129 ng/ml in 9 patients with prolactinomas. GH-secreting adenomas could be divided into 3 groups according to the proportions of the cell types. The GH cell dominant type had more than 70% GH cells. The mammosomatotroph cell dominant type had more than 80% mammosomatotrophs. The non-dominant type had no dominant cell type. There was a good correlation (r2=0.804) between serum GH levels and tumor size in patients with the GH cell dominant type (n=10). The nondominant type (n=8) had a low serum level of GH except for one tumor. The mammosomatotroph cell dominant type (n=1) showed high serum levels of both GH and PRL. All prolactinomas had a predominance of PRL cells. Sandwich CIBA is a simple method for detecting GH cells, mammosomatotrophs, and PRL cells, and useful for classification for GH-secreting adenomas.