Comparative inflammatory properties of staphylococcal superantigenic enterotoxins SEA and SEG: implications for septic shock

The severity of Staphylococcus aureus sepsis is positively associated with staphylococcal enterotoxin A (SEA) and negatively associated with the enterotoxin gene cluster (egc), which encodes five staphylococcal enterotoxins [1]. We postulated that the variable, clinical severity of S. aureus sepsis might he a result of differences in the inflammatory properties of staphylococcal superantigens. We therefore compared the inflammatory properties of SEA with those of staphylococcal ente rotoxin G (SEG), a member of the five egc superantigens. We found that SEA and SEG had similar superantigenic properties, as they induced CD69 expression on T lymphocytes and selective expansion of V beta subpopulations. Contrary to SEG, however, SEA induced a strong proinflammatory/Th1 response, including TNF-alpha and MIP-1 alpha production. These results suggest that the association of SEA with the severity of S. aureus septic shock, characterized by a deleterious, inflammatory cascade, may be explained partly by the specific proinflammatory properties of this superantigen. J. Leukoc. Biol. 80: 753-758; 2006.