What is the role of superantigens?

What is the role of superantigens?

Superantigens (SAgs) are a class of antigens that result in excessive activation of the immune system. Specifically it causes non-specific activation of T-cells resulting in polyclonal T cell activation and massive cytokine release.

What is a superantigen in microbiology?

Superantigens are unusual bacterial toxins that interact with exceedingly large numbers of T4-lymphocytes. They bind to the surface of the target cell but do not enter the cell. Figure 16.6. 1: Binding of Peptide Epitopes from Exogenous Antigens to MHC-II Molecules.

How do Superantigens cause disease?

Superantigens cause symptoms via release of immune cytokines. These proteins should be considered potential causes of illnesses such as rheumatic fever, arthritis, Kawasaki syndrome, atopic dermatitis, and guttate psoriasis because of their potent immune system-altering capacity.

What is a superantigen Slideshare?

INTRODUCTION  Superantigens (SAGs) are class of microbial antigens (viral, bacterial or mycoplasma proteins).  They non specifically activate large number of T cells and as a result they cause cytokine strom.

How are superantigens presented?

The superantigens are presented to T cells by direct binding to major histocompatibility (MHC) molecules present on the antigen-presenting cell (APC) surface, without MHC restriction, and specifically recognize the variable region of the β chain (Vβ) of T cell receptors (TCR) (Marrack and Kappler, 1990).

Are superantigens endotoxins or Exotoxins?

Endotoxin (lipopolysaccharide; LPS) and superantigens (exotoxins) have been identified as potent inducers of lethal shock. While endotoxin primarily interacts with CD14 receptors on macrophages, superantigens like the staphylococcal enterotoxin B (SEB) preferentially activate T cells.

What are superantigens Where do they come from?

Superantigen binding is predominantly controlled by the shape of the TCR-β variable region, and superantigens typically bind to all T-cell receptors that derive from a single family of TCR-β variable region gene segments (e.g., the Vβ8). Most known superantigens are produced by streptococci and staphylococci.

What are the clinical implications of superantigens?

These interactions lead to excessive production of proinflammatory cytokines and T cell proliferation, causing clinical symptoms that include fever, hypotension, and shock. Recent studies suggest that staphylococcal superantigens may also be involved in the pathogenesis of arthritis and other autoimmune disorders.

How do Superantigens suppress immunity?

Superantigens mislead the immune system These T-cell receptors (TCR) are normally quite specific to certain MHC-II/antigen combinations, and only need to bind very briefly for the T cell to be activated and initiate the immune response. It’s also a less specific process than a normal antigen-specific immune response.

What is the difference between antigen and superantigen?

Antigens are foreign substances (mostly proteins, polysaccharide) or altered self proteins that induces specific immune response. Superantigens are microbial peptides that can polyclonally activate large portion of T cells.

What are Superantigens Where do they come from?

Are Superantigens endotoxins or Exotoxins?