Several types of pathogens encode proteins that function as superantigens, which activate massive numbers of T cells in an individual. One example is the staphylococcal enterotoxins that cause food poisoning. These superantigens are the exception to the general rule that T cells only recognize specific peptide:MHC complexes, because they:
A) Induce activation of any T cell whose T-cell receptor uses a particular Vβ region bound by that superantigen
B) Simultaneously stimulate all of the T-cell receptors on a given T cell
C) Cover up the peptide-binding site, preventing MHC molecules from binding peptides
D) Activate a large number of T cells that are specifically recognizing peptides derived from the superantigen protein
E) Induce anti-microbial cytokine production that aids the immune system in clearing the pathogen

Question

Quizplus · Accepted Answer

Superantigens activate T cells by binding to a specific region (called Vβ region) of the T-cell receptor that is not involved in binding to peptides presented by MHC molecules. This allows the activation of a large number of T cells that bear that particular Vβ region, regardless of the specificity of their TCR for antigens presented by MHC molecules.

Several Types of Pathogens Encode Proteins That Function as Superantigens