CCR7 is required for the functional activity of naive- and effector/memory-like regulatory T cell subsets
(in cooperation with J. Hühn and A. Hamann, DRFZ, Berlin; M. Schneider and A. Rot, Novartis, Vienna)
Although CCR7 is crucial for homing of naive T cells as well as dendritic cells and consequent induction of adaptive immune responses, we recently showed that CCR7 deficient mice can also develop enhanced immune responses. Enhanced local immunity in these mice is caused by impaired CD4+CD25+ regulatory T cell (Treg) function. We found that naive-like and effector/memory-like regulatory T cell subsets express CCR7. Lack of CCR7 expression led to a strongly hampered migration of Tregs into lymph nodes accompanied by a severely reduced capacity to suppress antigen-induced naive T cell proliferation. In addition, CCR7 deficient regulatory T cells displayed an approximately twofold reduced capacity to protect in a transfer model mice from inflammatory bowel disease. Thus, CCR7 critically determines regulatory T cell in vivofunction by mediating their appropriate tissue localization.