Immunophenotyping in the classification of acute leukemia in adults. Interpretation of multiple lineage reactivity.

Fifty-nine adult patients with acute leukemia were classified using a combination of the French-American-British (FAB) criteria and characterization by immunophenotyping using flow cytometric study. The authors identified 51 patients with acute myeloblastic leukemia and eight with acute lymphoblastic leukemia. This procedure permitted lineage assignment in leukemias that otherwise might have been unclassifiable. In addition, the authors demonstrated that the leukemic blasts of 29% of patients with myeloblastic disease exhibited one or more T-cell antigens on their surface. The use of immunophenotyping has greatly enhanced the authors' ability to correctly identify the lineage of acute leukemias. The data, however, must be interpreted with caution with respect to diagnosing acute mixed lineage leukemias and must be integrated with the morphologic and cytochemical evaluation of traditional classification schemes. The possible significance of T-cell markers in myeloblastic leukemia is discussed.