TRANSFORMING GROWTH-FACTOR-ALPHA IMMUNOREACTIVITY IN A VARIETY OF EPITHELIAL TISSUES

The immunohistochemical expression of transforming growth factor-alpha (TGFalpha) has been examined in a range of normal adult epithelial ti ssues from both man and rat using an anti-hTGFalpha monoclonal antibod y (GF10). No differences in distribution were apparent between man and rat. In the continually renewing epithelium of the gastrointestinal t ract, no staining was seen within the proliferative compartments, but strong immuno-expression was noted in various differentiated populatio ns. In the testis, the spermatogonia were unstained, but the more lumi nally orientated germ cells were strongly positive. In the gastrointes tinal tract, at least, any mitogenic action of TGFalpha must be mediat ed through a relatively long paracrine loop. In contrast, the differen tiated parenchyma of kidney, salivary gland and liver remained unstain ed apart from collecting ducts in the kidney, striated ducts in saliva ry glands and bile ducts in the liver. The association of TGFalpha wit h tubule formation was reinforced by the very strong staining of newly forming bile ducts in a model of liver oval cell proliferation. Thus, in all the epithelia studied there was a distinct spatial pattern of TGFalpha immunoreactivity.