Evaluation of Controlled T Cell Activation with a Photoactivatable Peptide MHC

Begin by coating a coverglass with biotinylated poly-L-lysine to create a biotin-rich surface.

Next, introduce streptavidin — a protein that binds to biotin, forming a molecular bridge for subsequent interactions.

Thereafter, add biotinylated photocaged peptides bound to major histocompatibility complexes — pMHCs along with adhesion molecules.

The biotinylated pMHC ligands and the adhesion molecules interact with specific regions on the streptavidin, enabling their immobilization.

Next, wash the coverglass with buffered saline repeatedly and introduce T cells.

The presence of a photocage, a light-sensitive chemical group tethered to a specific residue on the peptide, obstructs the spontaneous binding of the T cell receptor to the peptide.

For controlled T cell activation, expose the photocaged peptides to ultraviolet light.

The UV light breaks the chemical bond between the photocage-peptide complex, exposing the native form of the peptide.

T cell receptors identify and attach to exposed peptides, while integrins bind to adhesion molecules, triggering T cell activation.