Human metallothionein gene expression determined by quantitative reverse transcription-polymerase chain reaction as a biomarker of cadmium exposure

Expression of the metallothionein (MT) gene in frozen human lymphocytes has been developed as a new molecular biomarker of heavy metal exposure, Workers at a Polish battery factory with high exposures to cadmium were monitored for airborne exposure and blood cadmium levels, A novel quantitative reverse transcription-PCR (RT-PCR) technique, making use of a homologous internal standard, was used to assess the level of MT-specific mRNA in frozen stored aliquots of blood samples taken from exposed and control workers, Results from this assay showed a statistically significant 2.5-fold increase in MT mRNA in exposed compared to control workers, The RT-PCR results also showed significant correlation with airborne cadmium, as registered on personal monitors and with blood cadmium levels, The results suggest that gene induction measured by quantitative RT-PCR is a promising approach for application as a biomarker of biologically effective dose in small samples of frozen tissues or cells.