Superantigens free essay sample

Superantigens BY Juell 1 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 a-cell superantigens describe the superantigens which ctivate a-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 (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. Cytokines, which are immune system proteins which are secreted for the purpose of carrying signals mongst cells, are released as a result of this increased activation of T cells and may even induce toxic shock. We will write a custom essay sample on Superantigens or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page This Toxic Shock Syndrome is due to Staphlyococcus aureus, characterized by 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 endothelial and vascular smooth muscle changes, hich 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 . 001-. 0001% of T cells are activated with a normal antigen response, about 20% of T cells are activated with superantigens.