The origin and spread of human leukemia

The human leukemias are a group of hematologic neoplasms characterized by uncontrolled proliferation of cells concerned with blood cell production. The cause(s) of human leukemia remains unknown. Bone marrow (BM) is believed to be the site of origin of human leukemias, although the specific locus(i) and/or cell(s) from which it arises have not been definitively identified. Generally, human leukemias and related proliferative diseases are thought to be clonal in nature; affecting a single hematopoietic stem cell, which then proliferates and replaces the marrow of normal hematopoietic stem cell systems. The condition is believed to be malignant in nature. Results of our current morphologic studies on well-fixed, ideally-stained thin sections of plastic-embedded bone marrow biopsies (BMB) from a large number of acute (AML, ALL) and chronic (CGL, CLL) leukemia patients suggest that human leukemias may not be clonal diseases. Instead, a large population of other resident cells--'endosteal cells'--appears to become involved in the process and it is possible that all members of this group enter the activity simultaneously. This change (transformation) in the endosteal cell population might be due to an abnormality (qualitative or quantitative) of diffusable, humoral factors (yet to be identified) that are responsible for the growth and proliferation of these hematopoietic precursor cells. In this context, the human leukemias may be considered not as malignant, but rather the result of an aberration of factor(s) that control hematopoiesis. In this respect, the human leukemias, particularly AML, ALL and CML, might be analogous to pernicious anemia (megaloblastic anemia) as it was understood 40-50 years ago.(ABSTRACT TRUNCATED AT 250 WORDS)