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

Also known as '''T lymphocytes'''

==Introduction==

==Introduction==

<p>T cells are so named as they differentiate in the [[Thymus - Anatomy & Physiology|thymus]]. They are long lived and are involved in '''cell mediated immunity'''. They represent 60-80% of the circulating lymphocytes and all express the markers CD2, CD3 and CD7 as well as having T cell receptors (TCR). Each T cell has 30,000 TCRs each of which is identical and recognises antigens and major histocompatability complex (MHC) II.</p><p>Functionally they are divided into three subsets that are distinguished by the presence or absence of CD4 or CD8 markers. CD4 and CD8 cells have α/β antigen receptors while the γδ cells have the γ/δ antigens receptors.</p>

<p>T cells are so named as they differentiate in the [[Thymus - Anatomy & Physiology|thymus]]. They are long lived and are involved in '''cell mediated immunity'''. They represent 60-80% of the circulating lymphocytes and all express the markers CD2, CD3 and CD7 as well as having T cell receptors (TCR). Each T cell has 30,000 TCRs each of which is identical and recognises antigens and major histocompatability complex (MHC) II.</p><p>Functionally they are divided into three subsets that are distinguished by the presence or absence of CD4 or CD8 markers. CD4 and CD8 cells have α/β antigen receptors while the γδ cells have the γ/δ antigens receptors.</p>