Conventional immunoassays underestimate anti-GST antibody titre.

This paper highlights problems associated with the quantitation of serum antibody levels to recombinant glutathione S-transferase (GST). Measurement of anti-GST antibodies in conventional immunoassays, where GST is bound directly to the ELISA plate, was found to substantially underestimate the amount of GST-specific antibody levels in test sera. This insensitivity in immunoassay of anti-GST antibodies can be overcome by using any one of several recombinant GST fusion proteins as the coating antigen in ELISA rather than simply GST. Comparison of anti-GST antibody titres assessed by the two procedures indicated that use of unfused GST underestimated the anti-GST antibody titre by more than ten-fold.