FoxP3+ T cells populate tumors and regulate anti-tumor immunity. The requirement for optimal population of FoxP3+ regulatory T cells in tumors remains unclear. We investigated the migration requirement and stability of tumor-associated FoxP3+ T cells. We found that only memory, but not naïve, FoxP3+ T cells are highly enriched in tumors. Almost all of the tumor-infiltrating FoxP3+ T cells express Helios, an antigen associated either with thymus-generated FoxP3+ T cells or activated T cells in the periphery. The tumor-infiltrating FoxP3+ T cells largely lack CD62L and CCR7, two trafficking receptors required for T cell migration into secondary lymphoid tissues. Instead, the tumor infiltrating FoxP3+ T cells highly express memory/tumor-associated CCR8 and CXCR4. Antigen priming is required for induction of this trafficking receptor phenotype in FoxP3+ T cells and only antigen primed, but not antigen-inexperienced naive, FoxP3+ T cells can efficiently migrate into tumors. While the migration of FoxP3+ T cells into tumors was a readily detectable event, generation of induced FoxP3+ T cells within tumors was unexpectedly inefficient. Genetic marking of current and ex-FoxP3+ T cells revealed that tumor-infiltrating FoxP3+ T cells are highly stable and do not readily convert back to FoxP3− T cells. Taken together, our results indicate that population of tumors with thymus-generated FoxP3+ T cells requires an antigen priming-dependent trafficking receptor switch in lymphoid tissues.


This is the publisher pdf of Wang C, Lee JH, Kim CH. Optimal population of FoxP3+ T cells in tumors requires an antigen priming-dependent trafficking receptor switch. 2012. PLoS One. 2012;7(1):e30 and is available at: 10.1371/journal.pone.0030793.

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