Primitive or progenitor hematologic cancer cells have been implicated in theearly stages and development of leukemia and malignant lymphoproliferativedisorders, including acute myelogenous leukemia (AML), chronic myelogenousleukemia (CML) and chronic lymphoid leukemia (CLL). Interleukin-3 receptoralpha chain (IL-3R.alpha. or CD123) is strongly expressed on progenitorhematologic cancer cells, but is virtually undetectable on normal bone marrowcells. The present invention provides methods of impairing progenitorhematologic cancer (e.g., leukemia and lymphomic) cells by selectivelytargeting cells expressing CD123. These methods are useful in the detectionand treatment of leukemias and malignant lymphoproliferative disorders. Alsoprovided are compounds useful for selectively binding to CD123 and impairingprogenitor hematologic cancer cells. These compounds may include cytotoxicmoieties such as, for example, radioisotopes or chemotherapeutics.
