Immunohistochemical analysis of distribution of RON receptor tyrosine kinase in human digestive organs

The immunohistochemical distribution of RON receptor tyrosine kinase in dig estive organs of both human fetus and adult, including the esophagus, stoma ch, duodenum, small intestine, colon, rectum, liver, gallbladder, pancreas, and spleen, was investigated semiquantitively using an affinity-purified r abbit polyclonal antibody. RON was observed to be widely distributed throug hout various digestive organs and cell types in humans. The immunoreactivit y for RON was observed in the epithelium of the esophagus, small intestine, colon, hepatocytes, Kupffer cells, and splenic macrophages both in the adu lt and the fetus, suggesting that the MSP/RON signaling pathway possesses t he proper biological properties to possibly be involved in morphogenesis or differentiation of cells in these organs and cell types. Several organs di ffered in immunoreactivity between adult and fetus. No immunoreactive cells were found in the pancreas of adults; however, immunoreactivity was observ ed in acinar cells and in some of the duct or ductular cells and endocrine cells of the islet of the fetus. Similarly, immunoreactivity was not observ ed in gastric mucosa except in the intestinal metaplastic cells in adults; however, immunoreactivity was found in the foveolar epithelium of the stoma ch of the fetus. Although the biological significance of RON in malignancy is unclear, the presence of RON immunoreactivity in the fetus and it lack i n the adult may indicate that RON is a oncofetal substance in human pancrea s and stomach.