Alpha-transforming growth factor in the bovine anterior pituitary gland: secretion by dispersed cells and immunohistochemical localization.

A growth factor secreted by bovine calf anterior pituitary cells in culture was purified, and its N-terminal amino acid sequence was determined. This sequence shows near-identity with human and rat alpha-transforming growth factor (alpha TGF). With the use of an anti-alpha TGF monoclonal antibody generated against a C-terminal rat alpha TGF synthetic peptide, alpha TGF-like material was localized by immunohistochemical techniques in the cytoplasm of normal bovine adenohypophysial cells. The antibody staining was immunospecific because it could be completely inhibited by saturating concentrations of the synthetic peptide to which it was raised. There was no immunoreactivity in cells of the intermediate and posterior lobes. Some of the cells containing alpha TGF immunoreactivity also contained PRL; alpha TGF immunoreactivity was not demonstrated in cells containing ACTH, TSH, FSH, and LH. This is the first report documenting the secretion of alpha TGF by nonneoplastic adult cells and the presence of alpha TGF immunoreactivity in the corresponding normal adult tissue.