FUNCTIONAL-CHARACTERIZATION OF THE INTERACTION BETWEEN THE SUPERANTIGEN STAPHYLOCOCCAL-ENTEROTOXIN-A AND THE TCR

In this report, we show that despite an overall amino acid residue ide ntity of more than 80% between the staphylococcal enterotoxins (SE) A and E, these proteins markedly differ in their absolute requirement fo r the MHC class II during T cell activation, The super-antigens were p roduced as C215Fab-SE fusion proteins and analyzed for their ability t o activate T cells in a MHC class II-independent manner, using C215 Ag expressing cell lines as pseudo super-APCs, C215Fab-SEA, but not C215 Fab-SEE, induced T cell cytotoxicity and proliferation in these MHC cl ass II-independent systems, Introduction of a region from SEA, compris ing amino acids 20-27, to SEE transferred the ability to engage T cell s in the absence of MHC class II, Analysis of the V beta specificity o f the chimeric SEA/SEE molecules and a panel of SEA mutants demonstrat ed that the site for TCR interaction covers the edge surrounding the s hallow cavity on top of the SEA molecule.