This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
Which among the following is true about Super antigens? 
Select and explain. 
A. They bind to the cleft of the MHC, B. Needs to processed before presentation, C. They are presented by APC' S to T cells, D. Directly attached to lateral aspect of TCR B chain
D: Directly attached to lateral aspect of TCR B chain
Answer: D: Directly attached to lateral aspect of TCR B chain 
Explanation: A group of antigens have been termed superantigens because they stimulate a much larger number of T cells than would be predicted based on the specificity of combining site diversity. This causes a massive cytokine release. The action of superantigens is based on their ability to bind directly to MHC proteins and to paicular V regions of the TCR without involving the antigen combining site. Individual superantigens recognize exposed poions defined by framework residues that are common to the structure of one or more V regions. Any T cells bearing those V sites may be directly stimulated. Ref: Ray C.G., Ryan K.J. (2010). Chapter 2. Immune Response to Infection. In C.G. Ray, K.J. Ryan (Eds), Sherris Medical Microbiology, 5e.