Expression of metallothionein isoforms in peripheral blood leukocytes from Thai population residing in cadmium-contaminated areas.

Metallothionein (MT) is a group of proteins with high cadmium (Cd) affinity and with a potential role in Cd transportation and detoxification. The aim of the present study was to investigate the relationship between MT (MT-1A, MT-2A, and MT-3 isoforms) gene expression level in peripheral blood leukocytes and Cd-associated renal injury in non-occupational exposed Thai population. The study was conducted in adult subjects residing in Cd-contaminated areas of Mae Sot District, Thailand. The basal levels of MT-1A, MT-2A, and MT-3 mRNA expression were determined in leukocytes by quantitative RT-PCR. MT-1A and MT-2A expressions, particularly MT-1A, were found to be significantly increased with elevated levels of blood and urinary Cd levels. In subjects with high urinary Cd levels, negative correlations between MT-1A and microalbumin, and between MT-2A and β(2)-MG, were observed. These results suggest that MT gene expression may reflect susceptibility of the exposed population to Cd-induced renal dysfunction. MT-1A mRNA expression in leukocytes might be developed as a potential biomarker of Cd exposure and Cd-induced renal dysfunction.