The present invention relates to a method of treating leukemia using rice prolamin, comprising administering a daily dose of isolated prolamin to a patient suffering from leukemia for a period of time from 5 days to 10 days. For the treatment application, the rice prolamin can stimulate human peripheral blood mononuclear cell (PBMC) to produce cytokines, such as tumor necrosis factor-alpha, to inhibit growth of and induce differentiation of human leukemia cells. The rice prolamin is gluten-free, thus will not trigger gastrointestinal allergic reaction, it also can decrease the tumor weight without changes in body weight and can inhibit the growth of peripheral blood leukocyte in leukemia mouse model.
