Expression of unusual immunophenotype combinations in acute myelogenous leukemia

Abstract

Immunophenotypes for 272 patients with acute myelogenous leukemia (AML) were analyzed using a panel of 22 antibodies. Numerical evidence for unusual coexpressions (present in normal marrow at < or = 0.1%) of surface markers on = or = 10% of the blast cells was found in 85% of all cases. Asynchronous expression of myeloid differentiation antigens occurred in 70% of the cases. Unusual coexpression of T-lymphoid, B- lymphoid, or natural killer (NK) markers with myeloid markers occurred in 38%, 13%, and 21%, respectively, of all AML cases. Two- and three- color analyses confirmed coexpression in 15 of 15 cases, and indicated that these percentages are an underestimate, because coexpression can be demonstrated in cases without numerical overlap. These data indicate that the unusual coexpression of normal differentiation antigens is a common occurrence in AML. Markers in 12 of 13 patients were similar between presentation and relapse, and in two patients, unusual phenotypes detected at first relapse were shown at second relapse, indicating these immunophenotypes are stable in the majority of AML patients. Significant correlations were found between t(8;21) cytogenetics and coexpression of CD19 with CD15 or CD34, t(9;22) and coexpression of CD19 and CD34, and t(15;17) and coexpression of CD2 and myeloid antigens. Multiparameter fluorescence analysis allows detection of unusual phenotypes when the blast counts are < 5% (classical remission). Analysis of 16 patients in remission indicated the presence of presentation phenotypes in 0.2% to 7.9% of the lymphocyte + blast light scatter region, representing 0.03% to 1.4% of the total nucleated marrow cells. Of the 16 patients with = or = 4 months follow-up after detection of these cells, 6 of 6 patients with = or = 0.2% unusual presentation phenotypic marrow cells have relapsed, while 9 of 10 patients with < 0.2% remain in remission. The detection of cells with the unusual presentation phenotype may reflect residual AML cells, and their increase may predict relapse.

Flow cytometric determination of the multidrug‐resistant phenotype in acute leukemia

“…Given this concern, the ability to clearly identify gated populations as leukemic is of utmost importance. The recent application of multiparameter flow cytometry to identify aberrant marker combinations as characteristic of leukemia cell populations may prove useful in this regard (5,33,41). Combining P-glycoprotein determinations with the ability to identify "novel" leukemic immunophenotypes may provide a more accurate assessment of multidrug resistance in the blast population.…”

The presence of leukaemia‐associated phenotypes is an independent predictor of induction failure in acute myeloid leukaemia

“…Asynchronous antigen expression, lineage infidelities and absence of lineage specific antigens were investigated. Thresholds for a positive LAP was defined as the co-expression of the aberrant phenotypic marker in at least 10% of CD34 + or CD117 + population and when CD34 and/or CD117 were negative, the co-expression with CD33 was considered (Reading et al, 1993).…”

U.S.‐Canadian consensus recommendations on the immunophenotypic analysis of hematologic neoplasia by flow cytometry: Medical indications

“…However, leukemic blasts can express combinations of antigens identified by two or more color staining techniques that are never or rarely observed in normal hematopoietic cells (21,22,84,138,151). Multidimensional (three or more color) flow cytometry can detect aberrant antigen expression in Ͼ75% of AML and ALL patients at diagnosis and identifies cells with a unique leukemia-associated phenotype in morphologically remission bone marrow specimens (87,117,132,148,149,(152)(153)(154)(155). The sensitivity of detection varies from 0.01% to 1.0% depending on the degree of antigenic aberration by the leukemia cells.…”

“…One important such distinction is between an increase in normal precursor B cells (hematogones), which are characteristic in their antigenic expression of CD10, CD19, CD20 (dim to absent), CD38, CD45, and sIg negativity, from leukemia blasts (47). Thus, FCM can be used not only for characterization of the cells at diagnosis, but detect to more accurately residual leukemia and the emergence of new leukemic clones post-therapy (75,84,117,138,173). This application of FCM on blood samples represents a source of improved medical practice both with regard to decreased patient discomfort and reduced utilization costs by eliminating the need for bone marrow aspirate and/or biopsy procedures.…”

“…Now with availability of techniques to fix cells for permeabilization and intracellular antigens detection by flow cytometry (39) or combined with aneuploidy detection (102), sensitivity using such technology is typically in the range of one target cell for every 10 3 -10 4 cells. One additional strategy for detecting malignant cells is the expression of aberrant phenotypes, not found on normal cells (21,87,113,117,162), which further enhances the sensitivity of minimal disease detection by multiparameter FCM.…”