Jean BERNARD * I should like to begin with an assumption and a paradox. The assumption is that leukemia is a disease of a stem cell characterized by pathologie alterations of that cell and its progeny. All present research and discussions are centered around the leukemic cell. So is this symposium, which would not take place except for our primary interest in the leukemic cell. This does not preclude, of course, consideration of other definitions and other approaches to the prOblem. By definition, then, the leukemic cells are abnormal cells and their metabolism and functions are presumed to...