Transforming growth factor-β1: Histochemical localization with antibodies to different epitopes

Abstract

We have localized transforming growth factor-β (TGF-β) in many cells and tissues with immunohistochemical methods, using two polyclonal antisera raised to different synthetic preparations of a peptide corresponding to the amino-terminal 30 amino acids of TGF-β1. These two antibodies give distinct staining patterns; the staining by anti-CC(1-30) is principally extracellular, while that by anti-LC(1-30) is intracellular. This differential staining pattern is consistently observed in several systems, including cultured tumor cells; mouse embryonic, neonatal, and adult tissues; bovine fibropapillomas; and human colon carcinomas. The extracellular staining by anti-CC(1-30) partially resembles that seen with an antibody to fibronectin, suggesting that extracellular TGF-β may be bound to matrix proteins. The intracellular staining by anti-LC(1-30) is similar to that seen with two other antibodies raised to peptides corresponding to either amino acids 266-278 of the TGF-β1 precursor sequence or to amino acids 50-75 of mature TGF-β1, suggesting that anti-LC(1-30) stains sites of TGF-β synthesis. Results from RIA and ELISAs indicate that anti-LC(1-30) and anti-CC(1-30) recognize different epitopes of this peptide and of TGF-β1 itself.