Abstract: CD4+CD25+regulatory T cells（Treg） is a subset with acknowledged specific function of inhibiting immune responses. CD4+CD25+regulatory T cells have been associated with prevention of antitumor immunity and the evasion of efficient recognition of tumor antigens. These T cells play critical roles in immunologic self-tolerance, anti-tumor immune responses, transplantation and so on. Treg cells could inhibit antitumor immunity. FOXP3 serves as an important regulator for the development and function of Treg cells. FOXP3 has emerged as a critical regulator of the development and function of CD4+CD25+ Treg cells. The regulatory effect of Treg cells is key in tumor immunotherapy.

Key words: T-Lymphocytes, regulatory, Immune tolerance, Neoplasms, Killer cells, natural