MEASUREMENT OF STAPHYLOCOCCAL EPIDERMOLYTIC TOXIN - COMPARISON OF BIOASSAY, RADIAL IMMUNODIFFUSION, AND RADIOIMMUNOASSAY

[摘要] Three methods of measuring the epidermolytic toxin of Staphylococcus aureus, bioassay in newborn mice, radial immunodiffusion and radioimmunoassay, were compared for reproducibility, specificity and sensitivity. The bioassay is highly specific and remains the only functional assay. It is reproducible only if newborn mice of the same age are used. The time required for epidermolysis follows a dose-response relationship only if concentrations of toxin large enough to cause peeling in .ltoreq. 90 min are used. This limits the sensitivity of the bioassay to about 5 .mu.g/ml. Single radial immunodiffusion in agar is a specific and reproducible assay method, but its sensitivity is about 5 .mu.g/ml. A radioimmunoassay was established by the Farr technique using purified epidermolysin radiolabeled with 125I. This assay was highly reproducible and specific. The staphylococcal products, .alpha.-toxin and enterotoxins A and B did not cross-react with anti-epidermolysin antibodies. The sensitivity of the radioimmunoassay is 20 ng/ml.