Changes

==T-Cell Activation==

==T-Cell Activation==

 

T cells function only after recent activation by an antigen.

* [[Lymphocytes#T cells|T cells]] function only after recent activation by antigen.

* CD4 binds [[Major Histocompatability Complexes#MHC II|MHC class II]] - [[Lymphocytes#Helper CD4+|CD4+ T-cells]] recognise antigen only in association with [[Major Histocompatability Complexes#MHC II|MHC class II]].

* CD4 binds [[Major Histocompatability Complexes#MHC II|MHC class II]].

* CD8 binds [[Major Histocompatability Complexes#MHC I|MHC class I]] - [[Lymphocytes#Cytotoxic CD8+|CD8+ T-cells]] recognise antigen only in association with [[Major Histocompatability Complexes#MHC I|MHC class I]].  

** [[Lymphocytes#Helper CD4+|CD4+ T-cells]] therefore recognise antigen only in association with [[Major Histocompatability Complexes#MHC II|MHC class II]]  

* CD8 binds [[Major Histocompatability Complexes#MHC I|MHC class I]].

** [[Lymphocytes#Cytotoxic CD8+|CD8+ T-cells]] recognise antigen only in association with [[Major Histocompatability Complexes#MHC I|MHC class I]].  

* Activation of [[Lymphocytes#T cells|T cells]] requires two distinct signals.  

* Activation of [[Lymphocytes#T cells|T cells]] requires two distinct signals.  

** '''Signal 1'''

** '''Signal 1'''