CD3(+)CD4(-)CD8(-) alpha beta-TCR+ T cell as immune regulatory cell

Down-regulation of immune responses by regulatory T cells is one of the maj or mechanisms involved in the induction of tolerance to self- and alloantig ens as demonstrated in a number of models of transplantation and autoimmuni ty. It is clear that regulatory T cells consist of different subsets. Recen tly a novel subset of antigen-specific alpha beta -TCR+ CD4(-)CD8(-) (doubl e negative, DN) regulatory T cells has been found to be able to inhibit the function of the CD8(+) T cells carrying the same T cell receptor specifici ty and prevent the rejection of skin allografts. Identification of the DN r egulatory T cells and their novel mechanism of suppression can help us to u nderstand how donor-specific transplantation tolerance can be achieved and to explain how tolerance to self-antigens can be maintained in the peripher y.