Specificity of the Localization of Transforming Growth Factor-α Immunoreactivity in Colon Mucosa

Abstract

Transforming growth factor-α (TGF-α) plays an important role in gastrointestinal pathophysiology. However, the exact location of its expression in the intestine is still controversial. This study systematically compared the localization of TGF-α immunoreactivity in frozen or fixed human colon using three different antibodies and examined specificity of antibodies by using tissues from TGF-α knockout mice and by Western blotting. Consistent with the mRNA distribution revealed by in situ hybridization, a similar staining pattern was obtained in frozen sections by all three antibodies, localizing on the surface and along the crypt epithelium. In paraffin sections, although the polyclonal antibodies (raised against recombinant human or rat TGF-α) gave minimal staining, the monoclonal antibody (against C-terminal peptide of human TGF-α) still gave intense staining on the surface and upper crypt epithelium. By using specimens from TGF-α knockout mice in immunostaining and Western blotting, the polyclonal antibodies were shown to be specific. In contrast, specificity of the monoclonal antibody was in doubt in rodent tissues because it gave similar detection between wild-type and knockout mice in both analyses, indicating its crossreaction to non-TGF-α molecules. In conclusion, frozen sections and antibodies raised from recombinant TGF-α should be used for TGF-α immunohistochemistry in the colon.