Abstract: Methods of stimulating or increasing differentiation to regulatory T cells, cultures of regulatory T cells and methods of reducing or decreasing an immune response, inflammation or an inflammatory response, among other things, are provided. Methods include, among other things, contacting blood cells or T cells with an amount of TGF-beta or a TGF-beta analogue and a retinoic acid receptor agonist, or an amount of a retinoid X receptor (RXR) or peroxisome proliferator activated receptor-gamma (PPARgamma) agonist, sufficient to stimulate or increase differentiation to regulatory T cells. Cultures of regulatory T cells include T cells that express a marker associated with regulatory T cells, such as cultures in which regulatory T cells represent, for example, 30% or more of the total number of cells in the culture.