Immune cells, called lymphocytes, form physical structures or synapses with specialized cells to trigger an immune response during pathogen attack. How synapses initiate immune responses during infection is not known, however. In the December issue of Nature Immunology, scientists report that 'microclusters' of molecules are the discrete physical structures required for triggering and, importantly, sustaining immune signals.
Previously, studies of synapses focused on large structures at the center of the synapses called central supramolecular clusters (cSMACs). Most studies have implicated cSMACs as the physical structures where lymphocyte signaling begins. But work by Takashi Saito and colleagues demonstrate instead that microclusters of tens of molecules form in the physical space around cSMACs -- and importantly precede cSMAC formation -- to initiate and sustain signaling. Their work also implies the contrary view that cSMACs actually stop signaling instead of starting it, an interpretation that decreases the importance of cSMACs while emphasizing microcluster formation as the critical event of lymphocyte activation -- a necessity for robust immune responses against pathogens.
Takashi Saito (RIKEN Research Center for Allergy and Immunology, Yokohama, Japan)
Abstract available online: Saito Paper.
(C) Nature Immunology press release.
Message posted by: Trevor M. D'Souza