Special regulatory T-cell review: Regulation of immune responses--examining the role of T cells.

The history of regulatory T cells goes back to the realisation that T cells could provide 'help' for antibody responses: the obverse of this is their ability to hold them in check. This brief personal overview follows the initial designation of T cells as 'suppressor' and the various hypotheses, some now disproved, put forward for their mechanism of action. We now cautiously label them T regulatory cells, but realise they do not control not all immune regulation. They probably operate through several mechanisms, and some of these are discussed.