ENZYME-LINKED IMMUNOSORBENT-ASSAY FOR HUMAN METALLOTHIONEIN - CORRELATION OF INDUCTION WITH INFECTION

  • 1 February 1989
    • journal article
    • research article
    • Vol. 113  (2) , 221-228
Abstract
Very little information is available concerning the relationship between metallothionein and disease in humans. Recently, investigators have used the Cd-heme method to measure metallothionein levels in human liver samples obtained from autopsy. This assay, however, is not sensitive enough to measure metallothionein in small tissue biopsy specimens. As an alternative, we report the development of a human metallothionein enzyme-linked immunosorbent assay (ELISA). This assay used high-performance liquid chromatography-purified human metallothionein-1 and purified sheep anti-human metallothionein-1 IgG. A limiting antigen coating concentration of 100 ng/ml and a minimal antibody dilution of 1:4000 were chosen. The sensitivity of the ELISA extended to 300 ng/ml (15 ng). The coefficients of interassay and intraassay variation were 15.4% and 4.2%, respectively. Human livers obtained from autopsy were assayed by this method and the values compared with values obtained by the Cd-heme method. The livers were separated by their autopsy reports into four groups: normal, immunosuppression, cancer, and infection. Livers from the infection group (ELISA 2979 .mu.g/gm, Cd-heme 1201 .mu.g/gm) contained significantly more metallothionein than those from the normal (ELISA, 1035 .mu.g/gm, Cd-heme 245 .mu.g/gm) and the immunosuppression (ELISA 1272 .mu.g/gm, Cd-heme 221 .mu.g/gm) groups (p < 0.05). The cancer group (ELISA 2415 .mu.g/gm) also had significantly elevated liver metallothionein levels. We conclude that this ELISA is sensitive enough for the measurement of tissue samples. Furthermore this assay is comparable to the Cd-heme assay in its ability to reflect metallothionein values among various treatment groups. We postulate that hepatic metallothionein induction is mediated by disease-related mechanisms such as interleukin-1, glucocorticold secretion, or both.