This report reviews the diagnostic significance of
immune markers, their relationship to patient outcome, and the
therapeutic uses of
monoclonal antibodies (MoAbs) in acute
leukemia. Immunophenotyping allows for rapid and reproducible diagnosis in the majority of cases of acute
leukemia. It is of particular importance in recognizing the major immunologic subclasses of
acute lymphoblastic leukemia (ALL), and in identifying subtypes of
acute myeloblastic leukemia (AML) which cannot be differentiated by morphology and cytochemistry alone, such as FAB M0 or M7.
Immune marker analysis has been used to detect
minimal residual disease in patients' bone marrow and CSF
after treatment. However, the presence of
leukemia-associated phenotypes on small numbers of normal cells may reduce the sensitivity of detection in some cases. The prognostic value of
immune markers in AML is limited. In ALL, the prognostic significance of the different immunophenotypic subtypes has been lessened by modern treatment protocols. The relationship of mixed-lineage or biphenotypic
antigen expression to patient outcome in both AML and ALL is unclear. Therapeutic applications of MoAbs in acute
leukemia include immunologic techniques for purging malignant cells from autografts prior to
transplantation, T-lymphocyte depletion from allografts as a strategy to reduce
graft-versus-host disease, and the use of flow cytometry to monitor the timing and extent of leukapheresis in
peripheral stem cell transplantation. MoAbs have also enabled the recent development of
transplantation protocols using positively-selected CD34+ stem cells.