The role of self-peptides in the development of CD4+ CD25+ regulatory T cells.

The thymus produces a unique lineage of cells known as CD4+ CD25+ regulatory T cells, and the exact processes leading to their development continue to be defined. Highly specific interactions between developing thymocytes and cognate self-antigens expressed by radioresistant elements in the thymus have been shown to drive CD4+ CD25+ regulatory-T-cell development. The self-peptide(s) that mediate thymic selection of CD4+ CD25+ regulatory T cells can also promote their expansion in the periphery, and self-peptides might also play a role in the conversion of CD4+ CD25- T cells into CD25+ regulatory T cells.