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Major histocompatibility complex class staphylococcal toxins

The staphylococcal superantigens initially bind to conserved elements on major histocompatibility complex class II molecules with relatively high affinity (A(i 10 mol 1 ). These receptors are found in abundance, throughout the body, on antigen-presenting cells such as macrophages and monocytes. However, each toxin... [Pg.160]

The coupling of superantigen—major histocompatibility complex class II to T-cell receptor swifdy results in cell-signaling cascades. ° These staphylococcal toxins can increase levels of phosphatidyl inositol from quiescent T cells, such as other mitogens, as well as elicit intracellular Ca movement that activates the protein kinase C (PKC) pathway important for interleukin-2 (IL-2) expression. " IL-2 is intimately linked to T-cell proliferation. In addition to the PKC pathway, the protein tyrosine kinase (PTK) pathway is also activated by superantigens, leading to elevated expression of various proinflammatory cytokines. Staphylococcal superantigens also potently activate transcriptional factors NF-/IB (nuclear factor kappa B) and AP-1 (activator protein-1), which subsequently elicit the synthesis of proinflammatory cytokines. " " ... [Pg.163]

Hartwig U, Gerlach D, Fleischer B Major histocompatibility complex class II binding site for streptococcal pyrogenic (erythrogenic) toxin A. Med Microbiol Immunol 1994 183 257-264. Hudson KR, Tiedemann RE, Urban RG, Lowe SC, Strominger JL, Fraser JD Staphylococcal enterotoxin A has two cooperative binding sites on major histocompatibility complex class II. J Exp Med 1995 182 711-720. [Pg.21]

Bavari S, Ulrich RG Staphylococcal enterotoxin A and toxic shock syndrome toxin compete with CD4 for human major histocompatibility complex class II binding. Infect Immun 1995 63 423 429. [Pg.178]

Staphylococcal enterotoxin B (SEB) is one of seven enterotoxins produced by strains of Staphylococcus aureus. SEB, the best understood of the staphylococcal enterotoxins, can be regarded as the type enterotoxin. Staphylococcal enterotoxins, toxic shock syndrome toxin-1 (TSST-1), and certain other bacterial products (such as streptococcal pyrogenic exotoxins [SPE]) and viral products (which are not discussed in this chapter) are commonly referred to as superantigens because of their profound effects on the immune system. Minute concentrations of superantigens can activate the immune system receptors because they bind with strong avidity to T-cell antigen receptors and class II molecules of the major histocompatibility complex (MHC). [Pg.622]

Streptococcus pyogenes and Staphyiococcus aureus secrete a number of enterotoxins and pyrogenic exotoxins, respectively. These toxins are known as superantigens, since they simultaneously form complexes with the major histocompatibility class II (MHC-II) molecules and T-cell receptors (TCRs) enabling them to activate a number of T-cell lymphocytes.Thus, superantigens stimulate up to 20% of the T cells while only 0.0001% to 0.001% T cells are stimulated upon normal antigen presentation. The massive T-cell activation leads to cytokine release and systemic shock. The staphylococcal enterotoxins (SE) A, B, C1-C3, D and... [Pg.5161]


See other pages where Major histocompatibility complex class staphylococcal toxins is mentioned: [Pg.163]    [Pg.166]    [Pg.167]    [Pg.277]    [Pg.215]    [Pg.1554]    [Pg.1012]   
See also in sourсe #XX -- [ Pg.29 , Pg.30 , Pg.162 ]




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