Sandwich ELISA for glutathione S-transferase Alpha 1-1: plasma concentrations in controls and in patients with gastrointestinal disorders.

Class Alpha glutathione S-transferases (GST-Alpha) are found in high concentrations in human liver. Increased plasma concentrations of GSTA1-1, the most abundant isoform of GST-Alpha, are a very sensitive marker for hepatocellular leakage. A sandwich-type ELISA was developed, based on a monoclonal antibody specific for human GSTA1-1 and a polyclonal rabbit anti-human GST-Alpha antiserum. The assay is specific for human GSTA1-1, and has a detection limit of 0.04 micrograms/L. The distribution of plasma GSTA1-1 concentrations in 350 blood donors was nearly normalized by logarithmic transformation and an upper normal reference concentration of 5.9 micrograms/L was calculated. Men had significantly higher plasma GSTA1-1 concentrations than women (P <0.0001). In women, but not in men, a significant increase was noted with age (P <0.05). In patients with inflammatory bowel disease (n= 210), gastrointestinal tumors (n= 70), irritable bowel disease (n= 36), or chronic pancreatitis (n= 12), plasma GSTA1-1 concentrations were similar to those of controls. In contrast, plasma GSTA1-1 concentrations were increased to a similar extent as alanine aminotransferase activities in patients with liver disorders (n= 37).