Building the immunological bull's eye

After an antigen-presenting cell meets a T cell, a bull's eye–shaped immunological synapse is formed, with T cell receptors (TCRs) and their antigen clustered in the center, surrounded by a ring of adhesion molecules that holds the cells together. According to Yoshihisa Kaizuka, Adam Douglass, Ronald Vale (University of California, San Francisco, CA), and colleagues, TCRs and adhesion molecules separate early during synapse formation. They might be further segregated by differential interactions with the T cell's actin cytoskeleton.

The movements of the T cell receptor were previously described, but little was known about the movements of adhesion molecules. Direct imaging of T cells in contact with a flat lipid bilayer containing the right ligands showed that TCRs and adhesion molecules initially clustered at the...