Superantigens are proteins capable of eliciting a very strong immune response because they activate more T cells than regular immune response In regular immune response only 0 0001 of the matured T cells are activated, whereas in case of superantigen mediated T cell activation, almost 20 of the matured T cells become active •Superantigens are produced by many bacteria, virus, like Streptococcus and Staphylococcus

1. Superantigen
• Superantigens are proteins capable of eliciting a very strong immune
response because they activate more T cells than regular immune response.
In regular immune response only 0.0001 % of the matured T cells are
activated, whereas in case of superantigen mediated T cell activation,
almost 20% of the matured T cells become active.
• Superantigens are produced by many bacteria, virus, like Streptococcus
and Staphylococcus.
• They interact with TCR differs from conventional antigen- TCR binding.
They lead to over-activation of the T cell to an infection.
• Conventional foreign antigens binds to the TCR at the defined antigen –
binding site. However, superantigen binds to a site on the TCR, that is
outside the antigen specific TCR binding site, these interactions stimulate
large number of T cells to active and proliferate. These T cells in turn
produce a large number of cytokines that stimulate other cells such as
macrophage and other phagocytes.
• Extensive cytokine production, thus, stimulate a wide spread cell mediated
response, systemic inflammatory reaction often result in diarrhea,
vomiting, systematic shock.
Example of Superantigen –
• Staphylococcus enterotoxins ( Toxic shock Syndrome),
• Streptococcal pyrogenic exotoxins (SPE),
• Staphylococcal enterotoxins (SE), and
• enterotoxogenic E. coli (ETEC) enterotoxin.