New methods are provided for suppressing the immune system and for treatingimmune related disorders. Therapies of the invention include administration ofan FLT3 inhibitor compound to a subject in need thereof, such as a subjectsuffering from organ rejection, bone marrow transplant rejection, acquiredimmune deficiency syndrome, arthritis, aplastic anemia, graft-versus-hostdisease, Graves' disease, established experimental allergicencephalitomyelitis, multiple sclerosis, lupus, or a neurological disorder.Methods are also provided for screening therapeutic agents for treating immunedisorders, including the use of a mouse having an elevated level of FLT3receptor activity.
