|Staphylococcal enterotoxins represent a group of proteins, which are secreted by Staphylococcus aureus and cause staphylococcal food poisoning syndrome. The illness is characterised by high fever, hypotension, diarrhea, shock, and in some cases death. Their molecular masses range between 27 and 30 kDa. At present, seven enterotoxins are known, namely A, B, C1, C2, C3, D and E. Their amino acid sequences have been determined and it was shown that all are single chain polypeptides containing one disulfide bond formed by two half cystines located in the middle of the polypeptide chain, which form the so called cysteine loop. SEB is an extremely potent activator of T cells, stimulating the production and secretion of various cytokines which mediate many of the toxic effects of SEB.