User:Eulemur2008/Infoboxes

Mast cells
Mast cells have been found to be involved in both the innate and adaptive immune systems. This stems from evidence such as the mast cells possession of toll-like receptors and the ability of mast cells to interact with dendritic cells, B cells, and T cells to help mediate adaptive immune functions. Mast cells have been shown to express working MHC class II molecules and can participate in antigen presentation. However the mast cell's role in antigen presentation is not very well understood. Mast cells have been shown to phagocytose, kill, and process antigens from gram-negative bacteria, such as salmonella, and that a mast cells' ability to process antigens is linked to the fimbrial proteins on the surface of bacteria. In addition to these functions mast cells produce cytokines that induce an inflammatory response. This is a vital part of the destruction of microbes because they attract more phagocytes to the site of infection.

Evolutionary origins
The ability of amoebas to distinguish between self and non-self is a pivotal one that is also found in the immune system.

Immunological tolerance
Dendritic cells also serve the function of promoting immunological tolerance. Immunological tolerance is important because it keeps the body from attacking itself. The first type of immunological tolerance is central tolerance: When T-cells first depart from the thymus, dendritic cells destroy the T-cells that carry antigens that would cause the immune system to attack itself. The second type of immunological tolerance is peripheral tolerance. Some T-cells that posses antigens that would cause them to attack self slip through the first process of tolerance, some T-cells develop self-attacking antigens later in life, and some self-attacking antigens are not found in the thymus; because of this dendritic cells, again, restrain their activity. Dendritic cells can do this by destroying them or by recruiting the help of regulatory T-cells to inactivate the harmful T-cells' activities. When immunological tolerance fails, an autoimmune diseases can follow. On the other hand, too much tolerance allows some diseases, like HIV, to go unnoticed.

Intro sentences

 * Dendritic cells also serve the function of promoting immunological tolerance; this keeps the body from attacking itself.


 * Amoebas behave much like macrophages and also have the ability (a pivotal one in the immune system) to distinguish between self and non-self when feeding.