A pro-inflammatory T cell response is specifically suppressed by the injection into a recipient of DNA encoding an autoantigen associated with autoimmune disease. The recipient may be further treating by co-vaccination with a DNA encoding a Th2 cytokine, particularly encoding IL4. In response to the vaccination, the proliferation of autoantigen-reactive T cells and the secretion of Th1 cytokines, including IL-2, IFN- and IL-15, are reduced.