Many human autoimmune diseases are still treated by a combination of corticosteroids and general immunosuppression. A better understanding of the pathogenesis of these diseases has led to therapies that are more specific than current therapies of some of these disorders. In psoriasis, T helper (Th) cells with a pro-inflammatory phenotype (Th1) are considered essential to the disease process. A recent clinical trial of interleukin 4 in psoriasis has demonstrated that such pleiotropic cytokines can be used safely and effectively to correct imbalances in immune function.