t-cell §

Antigen recognition §

The t-cell receptor.

Note n.b. γ:δ TCRs

A minority of t-cells bare a structurally similar TCR made up of γ and δ chains, and seem to have different antigen-recognition properties from the α:β TCRs.

Co-receptors are required to activate a t-cell §

CD4 and CD8 are co-receptors expressed by t-helper and cytotoxic t-cells respectively.

CD8 recognises MHC class I molecules and CD4 recognises MHC class II.

During antigen recognition, the co-receptor will associate with the TCR and bind to invariant sites on the MHC portion of the pMHC ligand (away from the binding site).

antigen processing and antigen presentation are important for inducing t-cell development and triggering the effector functions of these cells at the site of an infection.