Which of the following is not true regarding super-antigens -: (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 groov(e) in the MHC II molecule, (D) Binds directly to lateral aspect of T cell receptor
Answer is C. Superantigens Superantigens are potent activators of T-lymphocytes. 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 - a and IF - y. Superantigens are capable of activating up to 20% of the peripheral T-cell pool, where as conventional antigens activate < 1 in 10, 000. For superantigens, antigen specificity of TCR is not required.