Regulatory T cells--the renaissance of the suppressor T cells.

Immune reactions are stringently regulated and balanced by complex interactions of stimulating and suppressing mechanisms. Dysfunctions of this sophisticated immune regulatory network can lead to a variety of diseases such as autoimmunity, allergy, cancer, and pregnancy disorders. The rediscovery of suppressor T cells a decade ago--now designated as T regulatory cells--set off a huge avalanche of research activities leading to a multitude of preclinical and clinical studies. Herein, we give a comprehensive review about this research on T regulatory cells and the relevance of this suppressive T cell population for the development of innovative immune therapeutic strategies.