Expression of transforming growth factor alpha in human tissues: immunohistochemical study and northern blot analysis.

The expression of transforming growth factor alpha (TGF-alpha) was examined in various human tissues and the fetus, using immunohistochemistry and Northern blot analysis. TGF-alpha immunoreactivity was detected mainly in the epithelial cells of the digestive tract, liver, pancreas, kidney, thyroid, adrenal, skin, mammary gland and genital organs. In the digestive tract, epithelial cells with regenerative change or hyperplastic change showed strong immunoreactivity to TGF-alpha. Peripheral nerve, vessels, megakaryocytes and macrophages in the lung and spleen were also positive for TGF-alpha. By Northern blot analysis the expression of TGF-alpha mRNA was confirmed in the digestive tract, salivary gland, thyroid, kidney and mammary gland. In the human fetus, the nerve tissues, liver, adrenal and kidney were positive for TGF-alpha. Strong immunoreactivity to TGF-alpha was observed in the hepatocytes of the fetus. These findings indicate that TGF-alpha is produced by a variety of non-neoplastic cells in both adult and fetal tissues.