Which of the following is not true regarding super antigens - (AIPG, 2010)
|A||Bind T cells irrespective of antigen specificity of TCR|
|B||Bind directly to both MHC II and T cell receptor causing T cell activation.|
|C||Bind to cleft or antigen binding groove in the MHC II molecule|
|D||Binds directly to lateral aspect of T cell receptor|
[Ref Harrison 181hle p. 2671-2672 & 17lhle p. 2034]
a. Superantigens are potent. activators of T-lymphocytes.
b. Superantigens stimulate very large numbers of T cells, without relation to their epitope specificity. This leads to an excessive and dysregulated immune response with release of cytokines IL - 1, IL - 2, TNF - α and IF - γ
c. Conventional antigens bind to MHC class I or II molecules in the groove of the αβ dimer (T cell receptor).
d. However, superantigen bind directly to the lateral portion of TCR β chain and MHC class II β chain.
e. For superantigens, antigen specificity of TCR is not required.