In earlier studies immunological synapses were spotted only when an antigen- presenting cell met and activated a CD4 T cell. Although a CD8 cytotoxic T cell may attach to its victim for as little as two minutes, Gillian Griffiths and colleagues observed that synapses also formed during these contacts. The synapses have the characteristic bull's eye structure of a ring of adhesion proteins surrounding a ring of signaling proteins. The authors also showed that the cell-killing granules released by the cytotoxic T lymphocyte emerged from a focused secretory domain within the adhesion domain.The immunological synapse was thought to provide sustained signaling. But the new results suggest that the architecture of the synapse may help guide the secretion of molecules and prevent the death of nearby bystander cells, Griffiths says. She adds that the synapse may also participate in regulating the numbers of cytotoxic T cells....

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