ACUTE-LEUKEMIA COEXPRESSING MYELOID, B-LINEAGE AND T-LINEAGE ASSOCIATED MARKERS - MULTIPARAMETER ANALYSIS OF CRITERIA DEFINING LINEAGE COMMITMENT AND MATURATIONAL STAGE IN A CASE OF UNDIFFERENTIATED LEUKEMIA

Coexpression of myeloid, B-, and T-lineage associated markers was foun d in a patient with morphologically and cytochemically undifferentiate d acute leukemia. Surface marker analysis using two-color immunofluore scence staining characterized blast cells to express CD34, CD38, CD117 , and class II antigens, coexpressing TdT, CD4, CD7, CD13, CD19, and C D33. Cytoplasmic expression of myeloperoxidase, CD3, and CD22 could no t be demonstrated. Monosomy for chromosome 7 was found by cytogenetic analysis. The absence of clonal rearrangements of immunoglobulin or T- cell receptor genes was shown by Southern blot analysis. Using a H-3-t hymidine incorporation assay, DNA synthesis of leukemic blasts could b e stimulated by IL-3, IL-6 and G-CSF in vitro. The present case did no t offer specific criteria of lineage commitment. Corresponding to an e quivalent counterpart in normal hematopoiesis, the involved cell popul ation may reflect an early, most immature developmental stage within a multipotent progenitor cell compartment.