Biology of acute myeloid leukaemia.

The assessment of clonogenic leukaemic precursors in cell culture has demonstrated considerable heterogeneity of patients with respect to their ability to give rise to leukaemic blast cell colonies. Specific growth patterns rather than the frequency of blast colonies, appear to be of prognostic value for the clinical outcome. In particular, blast cells with high self-renewal ability were associated with poor prognosis. A similar degree of heterogeneity among leukaemic blast cell populations can be identified by studies with monoclonal antibodies directed against various cell surface cytoplasmic determinants that are associated with haematopoietic precursors. Some of these reflect properties of pluripotent normal counterparts while others display patterns that are associated with precursors restricted to a single myeloid lineage. Blast cells examined after culture may differ in their marker expression from the original blast cell population. Usually, properties of more mature cells are acquired during the culture period. These changes reflect events of aberrant differentiation without leading to the full development of a morphologically normal phenotype and functional capability. The use of both technologies has provided considerable insight into the biology of leukaemic blast cell populations and it is anticipated that their future use will provide further information about the control mechanisms involved in their proliferation and their potential to differentiate normally.