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No change in size ,  10:44, 16 May 2012
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*One pathway uses the CD95 (death receptor) which  triggers apoptosis in the target cell (usually other T cells)
 
*One pathway uses the CD95 (death receptor) which  triggers apoptosis in the target cell (usually other T cells)
 
*The other pathway uses perforins and granzymes which form pores in the target cell membrane causing cell lysis
 
*The other pathway uses perforins and granzymes which form pores in the target cell membrane causing cell lysis
**Perforins are structurally related to [[Complement*MAC|complement factor C9]]
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**Perforins are structurally related to [[Complement#MAC|complement factor C9]]
 
**Granzymes are proteolytic enzymes that target cell nucleases and cause apoptosis  
 
**Granzymes are proteolytic enzymes that target cell nucleases and cause apoptosis  
 
In both cases direct contact is required between the T cell and target cell, and cell killing can take several minutes.</p><p> Cytotoxic T cells secrete a pattern of cytokines similar to that of TH<sub>1</sub> cells i.e. IFN-γ but not IL-2. IFN-γ shifts the balance of the immune response in favour of TH<sub>1</sub> cells giving an increased level of T cell proliferation. The initiation of the immune response via cytotoxic T cells leads to the selective proliferation of cytotoxic T cells enhancing the main mechanism of killing infected cells.</p>
 
In both cases direct contact is required between the T cell and target cell, and cell killing can take several minutes.</p><p> Cytotoxic T cells secrete a pattern of cytokines similar to that of TH<sub>1</sub> cells i.e. IFN-γ but not IL-2. IFN-γ shifts the balance of the immune response in favour of TH<sub>1</sub> cells giving an increased level of T cell proliferation. The initiation of the immune response via cytotoxic T cells leads to the selective proliferation of cytotoxic T cells enhancing the main mechanism of killing infected cells.</p>
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