The Lymphoid Chemokine CCL21 Enhances the Cytotoxic T Lymphocyte‐Inducing Functions of Dendritic Cells

The potential use of lymphoid chemokines to generate a dendritic cell (DC) cancer vaccine is not yet clear. We investigated the effect of lymphoid chemokines on DC function and on the production of effective cytotoxic T lymphocytes (CTLs) for application of cancer vaccine using monocyte‐derived mature DCs (mDCs) prestimulated with lymphoid chemokines. mDCs exposed to a secondary lymphoid organ chemokine (SLC/CCL21) dramatically induced CTL response by increasing cytolytic activity without any significant alterations on expression of cell surface markers (e.g. CD80, CD83, CD86 and CCR7) or on the production of cytokines (e.g. IL‐12p70, IL‐10 and IL‐23). Interestingly, mDCs prestimulated with CCL21 showed higher levels of CXCL10 (IP‐10) production, but not the production of CCL22, compared with untreated mDCs. IP‐10 treatment during CTL generation with DCs dramatically enhanced tumour‐specific CTL response compared with untreated CTLs, and these enhanced CTL‐inducing functions of CCL21‐treated DCs were inhibited by anti‐IP‐10 treatment. Taken together, our data suggested an important role of the lymphoid‐endothelium‐associated chemokine, CCL21, on DCs in the induction of CTL responses.