CCR7

null C-C chemokine receptor type 7 (CCR7, CDw197) is the master homing receptor governing migration of lymphocytes and dendritic cells into secondary lymphoid organs. Its two ligands, CCL19 (ELC/MIP-3β) expressed on high endothelial venules and in T-cell zones, and CCL21 (SLC/6Ckine) produced by lymphatic endothelium and stromal cells, create stepwise chemoattractant gradients from peripheral tissues via afferent lymphatics into lymph nodes, spleen and Peyer's patches. CCR7 is constitutively expressed on naive T cells, central memory T cells, mature CCR7+ dendritic cells that have captured antigen, and B cells transiting through T-cell zones; beyond chemotaxis, CCR7 signaling co-stimulates T-cell survival and augments DC maturation. This receptor is indispensable for adaptive immunity initiation: Ccr7 knockout mice lack proper lymphoid architecture and mount delayed responses. Clinically, CCR7 expression stratifies tumor dissemination-high CCR7 on carcinoma cells predicts lymph node metastasis, while CCR7-guided dendritic cell migration is essential for vaccine efficacy and is harnessed in adoptive immunotherapy protocols.