Histological Demonstration of Immunoreactive Metallothionein in Rat and Human Tissues

Abstract

Antibody to rat liver metallothionein prepared by the method of Brady and Kafka (1979) was used to localise immunoreactive metallothionein using a sensitive DNP hapten sandwich technique applied to formalin fixed wax embedded tissues. Rat tissues examined were liver, kidney and small intestine, taken from normal animals, from animals fasted after receiving either an oral dose of water, or 1 ml zinc acetate solution either orally or by intraperitoneal injection, (3–4 mg Zn++/Kg body weight). Human tissues examined were 6 histologically normal liver biopsies and small intestine including histologically normal jejunal biopsies and samples of ileum obtained at operation. Pathological tissue including liver from cases of Indian childhood cirrhosis with copper retention and ileum from cases of inflammatory bowel disease were also examined. Immunoreactive metallothonein (IMT) was found in both rat and human liver localised in the hepatocyte cytoplasm, nucleus, sinusoids and canaliculi. In some livers IMT was found in the portal and hepatic veins. In the small intestine the IMT was localised consistently in the enterocyte cytoplasm and nucleus, and in the basement membrane region. The rat kidney IMT was localised in the cytoplasm of the distal convoluted tubules the collecting tubules and the ducts of Bellini. The distribution of IMT in rat tissues showed changes associated with fasting, stress and zinc administration. In man, inflammatory bowel disease appeared to decrease the intestinal IMT and no significant difference was seen when patients had received steroid therapy. The greatest amounts of IMT were seen in the control group of patients. The distribution of IMT in human liver in Indian childhood cirrhosis did not correspond with that of copper associated protein.