Targeting Foxp3+ regulatory T cells-related immunosuppression for cancer immunotherapy.

OBJECTIVE: To review the current research into Foxp3(+) regulatory T cells (Treg) cell surface molecules, plasticity of Treg cells and mechanisms of Treg cell suppression and to explore the possibilities to interfere in Treg cell suppression of anti-tumor immunity. DATA SOURCES: A literature search of all English articles was performed on the online electronic PubMed database dated 1995 to 2010. The keywords searched included: CD4(+)CD25(+)Foxp3(+) regulatory T lymphocytes, cancer, and immunotherapy. After finding relevant articles within these search limits, a manual search was conducted through the references from these articles. STUDY SELECTION: Articles regarding the role of Treg cells in tumor immunity and the utility of Treg cells in tumor immunotherapy. RESULTS: The results show that significant numbers of Treg cells are found in many tumors and it has been shown that the number of tumor infiltrating Treg cells correlates with adverse clinic outcomes. Treg cells are emerging as a key component of acquired tolerance to tumors. CONCLUSIONS: Several mechanisms of immunosuppression can be mediated by Treg cell function. Distinct immunosuppressive molecules expressed by Treg cells or diverse molecules related to Treg induction or migration represent potential drug targets for cancer immunotherapy.