Origin, function and distribution of regulatory T cells -- History of CD25+CD4+ regulatory T cells -- “Natural” and “induced” regulatory T cells — purpose and problems associated with an emerging distinction -- The role of interleukin-10 in regulatory-T-cell suppression: reconciling the discrepancies -- Activation and distribution of regulatory T cells in naïve and antigen-stimulated immune systems -- Regulatory T cells and the innate immune system -- The potential use of regulatory T cells in immunotherapy -- Exploiting the potential of regulatory T cells in the control of type 1 diabetes -- Regulatory T cells in type 1 autoimmune diabetes -- The potential for targeting CD4+CD25+ regulatory T cells in the treatment of multiple sclerosis in humans -- Immunotherapy of rheumatoid arthritis using CD4+CD25+ regulatory T cells -- Potential for manipulation of regulatory T cells in treatment or prevention of allergic disease -- The role of regulatory T cells in cutaneous disorders -- The potential role of CD25+CD4+ regulatory T cells in the induction and maintenance of transplantation tolerance in humans.