Histological demonstration of immunoreactive zinc metallothionein in liver and ileum of rat and man

A sensitive immunohistochemical technique was used to demonstrate zinc metallothionein in rat and human liver and ileum. In the liver, immunoreactivity was observed within the hepatocyte nucleus and cytoplasm, in sinusoids, canaliculi and blood vessels. In the ileum, immunoreactivity was present in the enterocyte nucleus and cytoplasm, and in the lamina propria. The effects of fasting alone and fasting with zinc injection were studied. In the liver, maximum staining was observed after 6 h fasting in the sinusoids, canaliculi and hepatocyte cytoplasm, and this pattern was not present in zinc injected animals. In the ileum, the greatest staining in the enterocyte cytoplasm and basal region was in control animals and after 6 and 12 h fasting. A similar pattern was observed in zinc-injected animals. Decreased staining was seen after 18 h fasting in both liver and ileum. In human ileum, the patients with colitis had less metallothionein immunoreactivity and those on steroid therapy had more immunoreactivity than the controls. We suggest a physiological transport and short term storage function for zinc metallothionein in rat and man.