Superantigens - Free Essay Example

Sample details Pages: 1 Words: 376 Downloads: 5 Date added: 2017/09/15 Category Advertising Essay Did you like this example? A superantigen is defined as a type of antigen which has the ability to cause polyclonal T cell activation via a large, nonspecific activation of T cells. There are three general families of superantigens: endogenous superantigens, exogenous superantigens, and B cell superantigens. Endogenous superantigens are encoded into the genome by different viruses; exogenous superantigens simply refer to toxins secreted by bacteria; and B-cell superantigens describe the superantigens which activate B-cells. Superantigens have the unique ability to bind to both T cells, as well as MHC class II molecules (MHC=major histocompatibility complex). Ultimately, the goal is to bring these two types of molecules together so that they can effectively activate even more T cells (â€Å"up to 20% of all T cells†) in a non-specific manner due to the superantigen binding to the Variable B region of T cells. Don’t waste time! Our writers will create an original "Superantigens" essay for you Create order Cytokines, which are immune system proteins which are secreted for the purpose of carrying signals amongst cells, are released as a result of this increased activation of T cells and may even induce toxic shock. This Toxic Shock Syndrome is due to Staphlyococcus aureus, characterized by â€Å"erythematous eruption and high fever†. An important cytokine molecule, TNF-alpha (tumor necrosis factor alpha), is secreted amongst these cytokines and plays a vital role in the inflammatory response of the body. An over secretion of TNF-alpha may result â€Å"endothelial and vascular smooth muscle changes, which manifests as hypotension, shock, and features of sepsis. † An example of a bacterium that elicits a superantigen response in humans is the bacterium Streptococcus pyogenes. The main difference between normal antigen responses and the superantigen response can be seen with different levels of T cell activation. While sapproximately â€Å". 001-. 0001%† of T cells are activated with a normal antigen response, about 20% of T cells are activated with superantigens. This increased activation is due to the non specific activation pathway that the superantigen goes through. Since it is non- specific, it leads to an abundance of immune system molecules. With normal antigen responses, the binding is very specific, so immune system responses are more controlled, hence more of a regulation in T cell number. Sources: https://dermatology. cdlib. org/142/reviews/superantigens/singh. html https://www. cell. com/immunity/retrieve/pii/S1074761300806469 https://www. ncbi. nlm. nih. gov/pmc/articles/PMC1808794/