Lymph delivers antigen-bearing dendritic cells (DCs), viral particles and extracellular bacteria to draining lymph nodes where T cells and B cells are primed. In Cell, Kastenmüller et al. and Sung et al. show how rapid cellular communication in lymph nodes helps to contain infectious agents. Infection of subcapsular macrophages at afferent lymph portals activates caspase-1 and the release of IL-18 and IFN-α/β. Within hours, NK cells, NKT cells and γδ T cells adjacent to those infected macrophages respond by producing IFN-γ, which in turn acts to recruit neutrophils and inflammatory monocytes into the infected lymph node. This response limits viral spread before the activation of naive antigen-specific lymphocytes. Similarly, during recall challenge, CXCR3+ central memory T cells are rapidly mobilized in lymph nodes by responding to subcapsular macrophage production of the chemokines CXCL10 and CXCL9. This faster mobilization to the site of viral infection, here in the lymph node, explains in part the greater efficiency of memory T cell responses than of primary T cell responses.

Cell 150, 1235–1248 & 1249–1263 (2012)