A radioimmunoassay for human metallothionein

Endogenous metallothionein (Mt) in human body fluids has never been reported due to the lack of a sensitive technique. Described will be a sensitive and accurate radioimmunoassay for human Mt utilizing an antibody developed to purified rat cadmium-binding protein. A high titer antiserum having complete cross-reactivity with human Mt was used at a final dilution of 1:20,000 to detect a routine lower sensitivity of 100–200 pg Mt. The same antiserum was subsequently used to measure Mt in plasma and urine of cadmium-exposed workers. Urinary Mt levels were found to have a close correlation with urinary Cd content, r = 0.89.