Metallothionein I isoform mRNA expression in peripheral lymphocytes as a biomarker for occupational cadmium exposure.

It is reported that metallothionein (MT) mRNA expression in human peripheral blood lymphocytes (HPBLs) could be used as exposure biomarkers in occupationally cadmium-exposed workers. Several MT isoforms have been identified in humans. The relationship between MT isoforms and cadmium toxicity has not been fully elucidated in occupational settings. In this study, the MT-IA, IE, IF, IX mRNA expressions in HPBLs were tested by RT-PCR technique, and the relationship between MT isoforms mRNA expression and cadmium-induced renal dysfunction was evaluated in cadmium-exposed workers. The MT-IE, IF, IX mRNA levels were found to increase with increasing blood cadmium (BCd) levels and MT-IA mRNA levels increased with increased urinary cadmium (UCd) levels. The MT-IE, IF, IX mRNA levels were significantly correlated with the BCd levels (P < 0.05), and MT-IA mRNA levels were significantly correlated with the UCd levels. This confirmed that MT-I isoforms mRNA expression in HPBLs is a biomarker of cadmium exposure and internal dose. The MT-IA mRNA levels were significantly correlated with renal dysfunction biomarkers, such as urinary beta2-microglobulin (Ubeta2-MG) (r = 0.294, P < 0.01) and urinary albumin (UALB) (r = 0.305, P < 0.01). The latter finding indicates that MT-IA mRNA expression in HPBLs may be used as a biomarker for renal dysfunction in occupational cadmium exposure.