Determination of the serum metallothionein (MT)1/2 concentration in patients with Wilson's disease and Menkes disease

We have developed an easy and specific enzyme-linked immunoassay (ELISA) for the simultaneous determination of serum metallothinein-1 (MT-1) and 2 (MT-2) in both humans and experimental animals. A competitive ELISA was established using a specific polyclonal antibody against rat MT-2. The antibody used for this ELISA had exhibited the same cross-reactivity with MT in humans and experimental animals. The NH2 terminal peptide of MT containing acetylated methionine was shown to be the epitope of this antibody. The reactivity of this ELISA system with the liver, kidney and brain in MT1/2 knock-out mice was significantly low, but was normal in an MT-3 knock-out mouse. The lowest detection limit of this ELISA was 0.6 ng/ml and the spiked MT-1was fully recovered from the plasma.We investigated the normal range of MT1/2 (25–75%tile) in 200 healthy human serum and found it to be 27–48 ng/ml, and this was compared with the serum levels in various liver diseases. The serum MT1/2 levels in chronic hepatitis C (HCV) patients were significantly lower than healthy controls and also other liver diseases. In the chronic hepatitis cases, the MT1/I2 levels increased gradually, followed by the progression of the disease to liver cirrhosis and hepatocellular carcinoma. In particular, we found significantly elevated MT1/2 plasma levels in Wilson's disease patients, levels which were very similar to those in the Long–Evans Cinnamon (LEC) rat (model animal of Wilson's disease). Furthermore, a significantly elevated MT1/2 level was found in patients with Menkes disease, an inborn error of copper metabolism such as Wilson's disease.