The present invention relates to improved methods of suppressing and/or preventing an undesired immune response comprising the use of CD83. In some embodiments, CD83 is coadministered to a subject with at least one other immunosuppressive compound. Methods are also provided for generating tolerogenic dendritic cells and regulatory T cells. These cells can be used in vitro to produce additional cells for therapeutic purposes or they can be used in vivo to suppress and/or prevent an undesired immune response. Methods of the invention can be used to prevent or reduce the severity of autoimmune diseases and can also be used to induce tolerance to at least one therapeutic composition, such as a therapeutic protein or transplanted tissue.
