The pyrogenic exotoxins of group A streptococci (SPEs) and the enterotoxins of Staphylococcus aureus (SEs) constitute a family of structurally related toxins that also share similar biologic activities.<sup>26 Hynes W.L., Weeks C.R., Iandolo J.J. , e al. Immunologic cross-reactivity of type A streptococcal exotoxin (erythrogenic toxin) and staphylococcal enterotoxins B and C1 Infect Immun 1987 ;  55 : 837-840

Cliccare qui per andare alla sezione Riferimenti, 30 Johnson L.P., L'Italien J.J., Schlievert P.M. Streptococcal pyrogenic exotoxin type A (scarlet fever toxin) is related to Staphylococcus aureus enterotoxin B Mol Gen Genet 1986 ;  203 : 354-356  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> They stimulate CD4, CD8, and γδ⁺ T cells by a unique mechanism. These toxins share the ability to bind the β chain variable region (Vβ) elements on the lateral face of the T cell receptor (TCR) and simultaneously bind to the lateral face of the class II major histocompatibility complex (MHC) of antigen-presenting cells (Figure 1), causing an aberrant proliferation of specific T cell subsets.<sup>13 Choi Y., Kotzin B., Herron L. , e al. Interaction of Staphylococcus aureus toxin superantigens with human T cells Proc Natl Acad Sci U S A 1989 ;  86 : 8941  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti, 15 Fleischer B., Schrezenmeier H. T cell stimulation by staphylococcal enterotoxins. Clonally variable response and requirement for major histocompatibility complex class II molecules on accessory or target cells J Exp Med 1988 ;  167 : 1697

Cliccare qui per andare alla sezione Riferimenti, 28 Janeway C.A.J., Yagi J., Conrad P.J. , e al. T-cell responses to Mls and to bacterial proteins that mimic its behavior Immunol Rev 1989 ;  107 : 61

Cliccare qui per andare alla sezione Riferimenti</sup> These toxins have been labeled as superantigens,<sup>68 White J., Herman A., Pullen A.M. , e al. The V beta-specific superantigen staphylococcal enterotoxin B: Stimulation of mature T cells and clonal deletion in neonatal mice Cell 1989 ;  56 : 27-35  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> because they do not interact with the MHC and TCR molecules in the manner of conventional antigens.<sup>31 Kappler J., Kotzin B.L., Herron L. , e al. Vβ-specific stimulation of human T-cells by staphylococcal toxins Science 1989 ;  248 : 705

Cliccare qui per andare alla sezione Riferimenti, 39 Marrack P., Blackman M., Kushnir E. , e al. The toxicity of staphylococcal enterotoxin B in mice is mediated by T cells J Exp Med 1990 ;  171 : 455  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> Superantigens have evolved independently over time from different genetic backgrounds, yet share common structural and functional elements.

These bacterial toxins cause a variety of syndromes in humans. The SEs have been implicated in staphylococcal food poisoning<sup>57 Spero L., Morlock B.A. Biological activities of the peptides of staphylococcal enterotoxin C formed by limited tryptic hydrolysis J Biol Chem 1978 ;  253 : 8787-8791

Cliccare qui per andare alla sezione Riferimenti</sup> and toxic shock–like syndromes.<sup>5 Bergdoll M.S. The staphylococcal enterotoxins—An update The Staphylococci New York: Gustav Fischer Verlag (1985). 

Cliccare qui per andare alla sezione Riferimenti</sup> The gene sequences and deduced amino acid sequences of at least seven staphylococcal enterotoxins are known: SEA, SEB, SEC, SED, SEE, and SEH.<sup>40 Marrack P., Kappler J. The staphylococcal enterotoxins and their relatives Science 1990 ;  248 : 705-711

Cliccare qui per andare alla sezione Riferimenti, 49 Ren K., Bannan J.D., Pancholi V. , e al. Characterization and biological properties of a new staphylococcal exotoxin J Exp Med 1994 ;  180 : 1675-1683  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup>

The SPEs have been implicated in causing the symptoms of scarlet fever and toxic shock–like syndrome.<sup>23 Hauser A.R., Stevens D.L., Kaplan E.L. , e al. Molecular analysis of pyrogenic exotoxins from Streptococcus pyogenes isolates associated with toxic shock–like syndrome J Clin Microbiol 1991 ;  29 : 1562-1567

Cliccare qui per andare alla sezione Riferimenti, 44 Musser J.M., Hauser A.R., Kim M.H. , e al. Streptococcus pyogenes causing toxic-shock-like syndrome and other invasive diseases: Clonal diversity and pyrogenic exotoxin expression Proc Nat Acad Sci U S A 1991 ;  88 : 2668-2672  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti, 60 Stevens D.L., Tanner M.H., Winship J. , e al. Severe group A streptococcal infections associated with a toxic shock-like syndrome and scarlet fever toxin A N Engl J Med 1989 ;  321 : 1-7  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> The sequences of three members of this family are known: SPEA, SPEC, and streptococcal superantigen (SSA).<sup>17 Goshorn S.C., Schlievert P.M. Nucleotide sequence of streptococcal exotoxin type C Infect Immun 1988 ;  56 : 2518-2520

Cliccare qui per andare alla sezione Riferimenti, 48 Reda K.B., Kapur V., Mollick J.A. , e al. Molecular characterization and phylogenetic distribution of the streptococcal superantigen gene (ssa) from Streptococcus pyogenes Infect Immun 1994 ;  62 : 1867-1874

Cliccare qui per andare alla sezione Riferimenti, 66 Weeks C.R., Ferretti J.J. Nucleotide sequence of the type A streptococcal exotoxin (erythrogenic toxin) gene from Streptococcus pyogenes bacteriophage T12 Infect Immun 1986 ;  52 : 144-150

Cliccare qui per andare alla sezione Riferimenti</sup>

Toxic shock syndrome toxin (TSST-1) from S. aureus shares similar biologic activity with the SEs and SPEs; however, amino acid sequences of this toxin are significantly different from the latter two classes of toxins.<sup>9 Blomster-Hautama D.A., Kreiswirth B.N., Kornblum J.S. , e al. The nucleotide and partial amino acid sequence of toxic shock syndrome toxin-1 J Biol Chem 1986 ;  261 : 15783-15786

Cliccare qui per andare alla sezione Riferimenti</sup> Structural analysis suggests that, despite the differences in amino acid composition, the overall topology of TSST-1 and the SE/SPE family of toxins is similar.<sup>1 Acharya K.R., Passalacqua E.F., Jones E.Y. , e al. Structural basis of superantigen action inferred from crystal structure of toxic-shock syndrome toxin-1 Nature 1994 ;  367 : 94-97  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup>