Changes

[[Image:TCR2.jpg|thumb|right|300px|T-cell receptor binds antigen fragments presented by MHC on the cell surface - B. Catchpole, RVC 2008]]

[[Image:TCR2.jpg|thumb|right|300px|T-cell receptor binds antigen fragments presented by MHC on the cell surface - B. Catchpole, RVC 2008]]

Also known as '''T lymphocytes'''<br />

Also known as '''T lymphocytes'''<br />

**Perforins are structurally related to [[Complement#Membrane Attack Complex|complement factor C9]]

**Perforins are structurally related to [[Complement#Membrane Attack Complex|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 TH₁ cells i.e. IFN-γ but not IL-2. IFN-γ shifts the balance of the immune response in favour of TH₁ 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 T_H1 cells i.e. IFN-γ but not IL-2. IFN-γ shifts the balance of the immune response in favour of TH₁ 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>

==γδ cells==

==γδ cells==

*One with restricted antigen binding, that act as first line defence against invading organisms and recognises antigens bound to MHC I complex

*One with restricted antigen binding, that act as first line defence against invading organisms and recognises antigens bound to MHC I complex

*The other subset doesn’t require the MHC complex and this subset has two further divisions

*The other subset doesn’t require the MHC complex and this subset has two further divisions

** One producing cytokines and chemokines  (TH₁ and TH₂)  

** One producing cytokines and chemokines  (T_H1 and T_H2)  

**The other having cytotoxic effects.</p>

**The other having cytotoxic effects.</p>

<br><br>

<br><br>

{{Jim Bee 2007}}

{{Jim Bee 2007}}

[[Category:Lymphocytes|D]]

[[Category:Lymphocytes|D]]