Toll-like Receptors Recommended that receptors is read before reading this page

Toll-like receptors(TLR's) are a comparatively new discovery in biology and as of only recently has the knowledge of TLR's been used in the study of immunology; which incorporates immunogenicity.
History of Toll-like Receptors In comparison to most discoveries of biology TLR's are fairly new. TLR's where first discovered unintentionally in 1985 when a group of German scientist found that when the Toll gene of fruit flies (D melanogaster) was manipulated certain proteins changed on the cells other then what was expected. These proteins where the TLRs of the fruit fly (Anderson, Bokla & Nüsslein-Volhard 1985).
The first TLR in humans where observed in 1994. Since then there has been 15 different TLR's that has been discover (named TRL 1 to TRL 15 accordingly), only 11 of which are found in humans. In 1997 the first theories where put forward into the role of TLR's in the immune system, and at this present time TLR's are widely believed to be a key part of the immune system (Medzhitov, Hurlburt & Janeway 1997).

Location of Toll-like Receptors Toll like receptors are only found on the membranes some cells which are part of the human/animal/insects immune system. The cells TLRs are found on are called 'antigen presenting cells' or APC's. It is the job of these cells to recognize any foreign antigen (a chemical molecule which is recognized by the immune system). Examples of APC's include macrophages and dentritic cells (Shaw 2008).
Picture: Shows that TLR's are located on the cell membrane next page
Contributed by Christopher Sutton