Logged out
Access All our Essays in an Instant
Swap your work for FREE access, or pay £4.99 for instant access
Positive & negative selection events, occuring within the thymus, are responsible for defining the peripheral T-cell repertoire - Compare & contrast these events & describe the consequences of either selection pressure.
Member rating: No Rating | Words: | Submitted: Mon Jun 19 2006
Page Preview
On the left is an image preview of every page of this document, and below are the first 150 words with formatting removed:
T. Konrad Rajab The Queen's College University of Oxford Positive & negative selection events, occuring within the thymus, are responsible for defining the peripheral T-cell repertoire. Compare & contrast these events & describe the consequences of either selection pressure. Introduction TCR rearrangement allows the adaptive immune system to generate an almost unlimited repertoire of T cell receptors. However, a functional T cell repertoire requires the ability to recognize foreign antigens presented by self-MHC as well as tolerance to self antigens. Positive and negative selection ensure that this requirement is met. In each case, an antigenic stimulus leads to a paradoxical outcome: survival in the case of positive selection and apoptosis in the case of negative selection. This essay will outline the mechanisms and outcomes of these events. Furthermore, the differences will be highlighted. Positive selection involves combinatorial recognition of MHC + peptide and restricts the T cell repertoire to auto-MHC Early evidence for a mechanism which positively...
Get instant access
- Instant, unlimited access to our documents in full
- Swap your work for free access, or pay £4.99
- To see the full version of this document and 149,437 others
