FTY720 is an immune modulator that targets sphingosine 1-phosphate (S1P) receptors. It is effective in transplant and autoimmune models without causing generalized immunosuppression and is effective in human kidney transplantation. FTY720 induces lymphopenia by redistributing lymphocytes from circulation to secondary lymphoid tissues. It is phosphorylated by sphingosine kinase, forming a potent agonist at four S1P receptors, which is the therapeutic principle in a multiple sclerosis model. FTY720 is derived from ISP-1, a fungal metabolite used in traditional Chinese medicine. It is a novel, high-potency immune modulator effective in various autoimmune and transplant models. Unlike traditional immunosuppressants, FTY720 does not inhibit T cell activation and is effective against systemic viral infections. It sequesters lymphocytes from circulation, reducing effector T cells in inflamed tissues and graft sites. FTY720 acts through S1P signaling pathways, modulating chemotactic responses and lymphocyte trafficking. It is a potent agonist at S1P receptors, including S1P4, S1P1, S1P3, and S1P5. FTY720-P, its phosphorylated form, is more potent than non-phosphorylated compounds. FTY720 prevents the development of experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis. It is less toxic than existing immunosuppressants and does not impair immunity to systemic viral infections. FTY720 may be used to treat autoimmune disorders and inflammatory processes associated with chronic viral infections. The drug's mechanism involves S1P signaling, which regulates lymphocyte trafficking and immune system modulation. FTY720 represents a new class of immune modulators with potential for better management of allograft recipients and more effective treatment of autoimmune disorders.FTY720 is an immune modulator that targets sphingosine 1-phosphate (S1P) receptors. It is effective in transplant and autoimmune models without causing generalized immunosuppression and is effective in human kidney transplantation. FTY720 induces lymphopenia by redistributing lymphocytes from circulation to secondary lymphoid tissues. It is phosphorylated by sphingosine kinase, forming a potent agonist at four S1P receptors, which is the therapeutic principle in a multiple sclerosis model. FTY720 is derived from ISP-1, a fungal metabolite used in traditional Chinese medicine. It is a novel, high-potency immune modulator effective in various autoimmune and transplant models. Unlike traditional immunosuppressants, FTY720 does not inhibit T cell activation and is effective against systemic viral infections. It sequesters lymphocytes from circulation, reducing effector T cells in inflamed tissues and graft sites. FTY720 acts through S1P signaling pathways, modulating chemotactic responses and lymphocyte trafficking. It is a potent agonist at S1P receptors, including S1P4, S1P1, S1P3, and S1P5. FTY720-P, its phosphorylated form, is more potent than non-phosphorylated compounds. FTY720 prevents the development of experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis. It is less toxic than existing immunosuppressants and does not impair immunity to systemic viral infections. FTY720 may be used to treat autoimmune disorders and inflammatory processes associated with chronic viral infections. The drug's mechanism involves S1P signaling, which regulates lymphocyte trafficking and immune system modulation. FTY720 represents a new class of immune modulators with potential for better management of allograft recipients and more effective treatment of autoimmune disorders.