Lymph node choreography: Treg cells join the dance.

This article discusses the potential of regulatory T cells in suppressing immune responses in vivo. Regulatory T cells may act on prime T cells by inducing the secretion of suppressive cytokines or the decrease of tryptophan metabolism. Alternatively, suppression may involve direct contact between regulatory T cells and effector T cells. Regulatory T cells may also have the ability to kill activated T cells in a perforin-dependent way. Finally, cytokines such as interleukin 10 or transforming growth factor, produced by regulatory T cells or other cells, may exert local suppression.