Changes

===Killing Mechanism===

===Killing Mechanism===

 

The CTl killing mechanism is initiated by direct CTL-target cell contact.   

* The CTl killing mechanism is initiated by direct CTL-target cell contact.   

* The cells involved bind by antigen/[[MHC]] class I-TcR interaction. This allows the CTL's intracellular granules to be localised at the area of contact - the granules contain most of the molecules responsible for cytotoxicity.  

* The cells involved bind by antigen/[[MHC]] class I-TcR interaction.

* Direct cell contact stimulates the release of the granule contents into the area of contact between the two cells. The granules contain two groups of cytotoxic molecules.

** This results in the CTL's intracellular granules becoming localised to the area of contact.

#Perforin, which is structurally related to the [[Complement|complement]] component, C9 and forms pores in the cell membrane.

*** These granules contain most of the molecules responsible for cytotoxicity.  

#Granzymes, which are proteolytic enzymes that target cell nucleases and cause programmed cell death.

* Direct cell contact stimulates the release of the granule contents into the area of contact between the two cells.  

* The granules contain two groups of cytotoxic molecules.

** Perforin.

*** Structurally related to the [[Complement|complement]] component, C9.

*** Forms pores in the cell membrane.

** Granzymes.

*** Proteolytic enzymes.

*** Target cell nucleases.

*** Cause programmed cell death.

==T-Cell Activation==

==T-Cell Activation==