\"Superantigens\" have the ability to nonspecifically bind to a large number of
ID: 252306 • Letter: #
Question
"Superantigens" have the ability to nonspecifically bind to a large number of V regions on TCRs and to MHC-II molecules on APCs 2. APC MHC class II Superantigen TCR T cell signal Signal Trsned uct0 A typical superantigen may crosslink MHC-II molecules to TCRs on as many as 20% of CD4+ T cells. Superantigens are distinct from "normal" antigens and they do not bind to the antigen-binding groove (see image above). In Toxic Shock Syndrome, caused by the TSST1 toxin from Staphylococcus aureus, TSST1 toxin has been demonstrated to be a superantigen that causes high fever, shock, and a diffuse erythematous rash. It can be life threatening. Given the above information, what do you think is the pathogenic basis of this syndrome?Explanation / Answer
Toxic shock syndrome and it’s pathogenicity is progressed through a superwntigen toxin which would be causing a non specific binding to the MHCII along with the T cell receptors. As a result of this, there would be an activation of the polyclonal T cells. In the normal conditions, antigen would be taken up by the antigen presenting cells and would be processed as well as expressed on MHC class II molecules.
In this case, the superantigens will not be requiring this processing that is done by the APCs and these would be directly interacting with the invariant region present in the MHC II molecules. Patients having TSS, there would activation of 20% of the cells of the body. This results in a cytokines form resulting in a multi system disease.
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