The enrichment of Foxp3+ regulatory T cells (Tregs) constitutes a central mechanism of immune regulation, but has also been associated with poor patient prognosis in a variety of human cancers. Previous studies have suggested that Treg development, specificity, and mechanism of action are dependent upon antigen recognition; however, little is known about the identity of the antigen presenting cells (APCs) that are directly recognized by Tregs in vivo. Previously, we have identified an endogenously occurring monospecific Treg population, termed “MJ23 Tregs,” that is highly enriched in the prostate tumors of TRAMP mice. Using MJ23 T cells as a probe, we have determined that despite the presence of multiple MHC class II-expressing cell types within tumor lesions, the antigen recognized by MJ23 Tregs is exclusively presented by a distinct subset of dendritic cells (DCs). In order to determine the functional significance of this interaction, ongoing work aims to determine the impact of DC ablation on Treg localization and function, and on prostate cancer development. In all, our work will determine the extent to which the activity of Tregs within tumor lesions is coordinated in trans by the APC.
- Copyright © 2013 by The American Association of Immunologists, Inc.