Detection of staphylococcal enterotoxin in gastric juice

The gastric juice of a patient showing symptoms of staphylococcal food poisoning was examined by a radioimmunoassay for the presence of enterotoxins. Assays gave markedly higher results at 35 degrees than at 5 degrees. The source for this discrepancy was attributed to interference due to trypsin activity on the basis of (1) the demonstration of hydrolysis of p-toluenesulfonyl-L-arginine methyl ester by the specimen, (2) inhibition of this activity by trypsin inhibitor from lima bean, and (3) lowered values produced for enterotoxins in gastric juice when the inhibitor was included in the assay system.