Dancing the Immunological Two-Step

The delicate dance between T cells and antigen presenting cells enables the T cell receptor to engage with specific peptide-MHC molecules on the surface of the antigen presenting cell, resulting in T cell activation. In his Perspective, Bernard Malissen describes the molecular choreography, revealed by real-time imaging ( Grakoui et al .), that leads to formation of immunological synapses between T cells and their partners.