What is meant by superantigen?

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.

How does superantigen work?

Superantigens are bacterial proteins that generate a powerful immune response by binding to Major Histocompatibility Complex class II molecules on antigen-presenting cells and T cell receptors on T cells.

What is the function of a superantigen in T cell activation?

Microbial superantigens are thought to initiate an immediate T cell response by direct binding to the T cell receptor V β region, bypassing the MHC complex and the need for antigen processing and presentation. This could be an initiating step of autoimmunity.

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 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 examples of superantigens?

Examples of superantigens include toxic shock syndrome toxin-1 (TSST-1), Streptococcal pyrogenic exotoxins (SPE), Staphylococcal enterotoxins (SE), and enterotoxogenic E. coli (ETEC) enterotoxin.

Why does superantigen elicit strong immune response?

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 type of toxin is a superantigen?

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 6.2A. 1: Binding of Peptide Epitopes from Exogenous Antigens to MHC-II Molecules.

What is an example of a superantigen?

Is Mycoplasma arthritidis the same as M pulmonis?

Other murine mycoplasmas Mycoplasma arthritidis is antigenically related to M. pulmonis. Therefore, serological evidence of mycoplasma infection must be supplemented by other diagnostic tests, as outlined above, to differentiate between these agents.

Do Mycoplasma-derived superantigens induce T cell–independent cytokines?

Mycoplasma-derived superantigens such as from Mycoplasma arthritidis can directly induce T cell–independent cytokine production by macrophages and exacerbate or trigger arthritis in mice immunized with type II collagen.

What is Mycoplasma neurolyticum Rolling disease?

Mycoplasma neurolyticum is the etiological agent of rolling disease, a rare syndrome which occurs within hours after intravenous inoculation of M. neurolytica exotoxin. Characteristic clinical signs include spasmodic hyperextension of the head and the raising of one foreleg followed by intermittent rolling on the long axis of the body.

What is Mycoplasma phage mav1?

Mycoplasma phage MAV1 is a lysogenic phage of Mycoplasma arthritidis with ds linear DNA genome of about 16 kb.