The use of monoclonal antibodies for the identification and classification of acute myeloid leukemias.

We reviewed a library of monoclonal antibodies (MoAbs) detecting antigens on myelomonocytic cells and analysed their reactivity patterns as reported in the literature. On the basis of the frequency of positivity with the myelocytic variants (FAB M1-3) or monocytic variants (FAB M4/5) of acute myeloid leukemias, the MoAbs were assigned to one of four groups. MoAbs of Group I identified most cases of both the myelocytic and the monocytic cell lineages ('pan-myelomonocytic' reactivity) and can be used to identify acute myeloid leukemias regardless of the subtype. Group II comprised MoAbs which reacted with the majority of FAB M1-3 cases, but showed a preference in reactivity with AMMoL/AMoL cases (reactivity: myelocytic partly, monocytic predominantly). MoAbs of Group III stained most cases with monocytic phenotypes, but labelled only a small percentage of non-monocytic cases. These MoAbs are valuable tools for the detection of cases with monocytic features. Group IV MoAbs reacted with a small to intermediate percentage of myelocytic and/or monocytic cases. Besides their diagnostic application MoAbs might be used in new therapeutic approaches such as in-vivo serotherapy with MoAbs and purging of autologous bone marrow for transplantation. None of the described MoAbs appear to be leukemia-specific. Many MoAbs have been produced against non-myelomonocytic cells and were reactive with cells outside the myelomonocytic cell lineages and the hematopoietic system. Other MoAbs with apparent cell lineage-restricted reactivity regarding normal cells stained leukemic cells of other cell lineages. This phenomenon of translineage reactivity of leukemic cells with mutually exclusive markers indicating a biphenotypic marker profile might be the result of abnormal, disregulated gene expression. New classification systems of acute myeloid leukemias based on immunological marker profiles have been proposed. The analysis of reactivity of normal and malignant myelomonocytic cells with MoAbs has led to refined differentiation schemes of the normal hematopoiesis.