New competitive enzyme-linked immunosorbent assay for determination of metallothionein in tissue and sera

Very little information is available concerning the relationship between metallothionein (MT) and diseases in humans. Several methods to measure MT levels exist but many of these assays are not sensitive to measure MT in human sera. A new sensitive competitive ELISA system has been developed using MT labeled with horseradish peroxidase as a conjugate and high-titre polyclonal antibodies obtained from rabbit immunoglobulin G for MT determination in human sera. The cELISA proposed here permits a reliable determination of MT in the range 10-2000000 pg ml(-1). The method was compared with Cd-hem assay and showed good agreement of results. The recovery of the assay was determined by spiking rat MT into rat and human sera, and comparing it with spiked diluent controls. The overall recoveries of the added MT were 101% for rat sera and 89% for human sera. The variation within-assay and between assay were 3 and 6%, respectively. A significant difference (P < 0.001) was found between the MT-level in human sera from patient with essential hypertension (646 +/- 223 ng ml(-1), n = 90) and normotensive subjects (21 +/- 18 ng ml(-1), n = 236). A correlation between arterial hypertension and MT-level seems possible. A very sensitive new cELISA method was presented for determination of MT in sera and tissues. It enables investigation of possible correlations between sera MT-concentration and certain diseases. (C) 1998 Elsevier Science B.V. All rights reserved.