Phenotypical characteristics of acute myelocytic leukemia associated with the t(8;21)(q22;q22) chromosomal abnormality: frequent expression of immature B-cell antigen CD19 together with stem cell antigen CD34.

Twenty-three acute myelocytic leukemia (AML) patients with t(8;21) chromosomal abnormality, all classified as M2 (French-American-British [FAB] classification), were investigated. Blastic cells from all patients were positive for the stem cell-associated antigens, CD34 and HLA-DR, and the immature myeloid antigens, CD13 and CD33. The nonblastic leukemic cells expressed the more mature myeloid antigens, CD11b and CD15, with loss of the immature phenotype. The incidence of positivities for the stem cell-associated antigens, CD34 and HLA-DR, in t(8;21) AML cells was significantly higher in comparison with those in other AML showing granulocytic differentiation (M2 or M3). AML cells with t(8;21) also showed some phenotypic abnormalities. Frequent expression of CD19 was found in the blastic population of t(8;21) AML (18 of 23 cases) without other B-cell antigens and Ig gene rearrangements. CD19 expression was confirmed by immunocytochemistry and Northern blotting. The CD19+ blastic cells coexpressed both CD34 and HLA-DR. In addition, CD33+ cells among the blastic fraction in t(8;21) AML cells were fewer in number than in those of M2 or M3 AML without t(8;21). Our findings indicate that leukemic blasts of t(8;21) AML commonly express CD19 while preserving the stem cell-associated antigens, and differentiate into the granulocytic pathway with discordant maturation such as low CD33 expression.     

Acute myeloid leukemia M2 and t(8;21)(q22;q22) with an unusual phenotype: myeloperoxidase (+), CD13 (–), CD14 (–), and CD33 (–)

 Cases of myeloid surface antigen-negative acute myeloid leukemia (AML) are rare. We describe the morphological, cytochemical, immunologic, and cytogenetic features of two patients with AML with maturation (FAB M2) and the phenotype MPO+, CD13 (–), CD33(–), CD56(+). Cytogenetic studies demonstrated t(8;21)(q22;q22). These findings suggest an association between the lack of CD13 and CD33 in myeloperoxidase-positive AML and the presence of t(8;21). Received: August 8, 1998 / Accepted: January 27, 1999     

Myeloid enzymes profile related to the immunophenotypic characteristics of blast cells from patients with acute myeloid leukemia (AML) at diagnosis

The purpose of this study was to assess the possible relationship between the cytochemical enzyme profile and immunophenotypic characteristics of distinct acute myeloid leukemia (AML) subtypes in discrete stages of leukemic cells maturation. As the proportion of leukemic blast cells is critical for exact cytochemical analysis, study was restricted to the evaluation of 48 adult and pediatric patients with newly diagnosed AMLs with 80% or more blasts in analyzed samples. The cytochemical investigation of myeloperoxidase (MPO), Sudan black B (SBB), chloroacetate esterase (CAE), alpha-naphthyl butyrate esterase (ANBE), alpha-naphthyl acetate esterase (ANAE) and acid phosphatase (AP) in peripheral blood and/or bone marrow was performed. The immunophenotype was examined for the maturation dependent myeloid antigens CD13, CD33, CD11b, CD14, CD15, CD65, CD36, cytoplasmic MPO, non-lineage associated CD34 and HLA-DR antigens, lymphoid- associated antigens CD7, CD4, CD38 as well as natural killer cell associated marker CD56. Flow cytometry by double marker staining and visualization of pathologic cells in dot plots reflected immunophenotypic aberrancy and degree of cell maturation. The patients were classified into AML subtypes M0- M2, M3, M4 and M5 according to the main morphological, cytochemical and immunophenotypical features. The variable combinations of MPO, SBB, CAE and ANBE were identified in relation to immunophenotype. The cytochemical profile of blasts was in concordance with immunophenotype, particularly in more differentiated AML subtypes, M3, M4 and M5. The findings of myeloid antigens expression and cytochemical features in poorly differentiated AML subtypes showed no practical relevance of cytochemical analysis. Notwithstanding that the cytochemical analysis of AML subtypes not sufficiently identifies the distinct aberrancies in heterogeneous leukemic blast cell populations, evaluation of the cytochemical profile in connection with immunophenotyping may help to classify the AML patients to relevant subtypes with more accuracy.     

CD19-positive acute myeloblastic leukemia developed 12 years after the onset of hypereosinophilic syndrome

We report a rare case of hypereosinophilic syndrome (HES) that developed to acute myeloblastic leukemia (AML). The patient, a 34-year-old man, presented with eosinophilia of unknown origin (white blood cells 38,200/microliter with 74% eosinophils) and pericardial effusion, and was diagnosed as having HES with a normal karyotype. He received four cycles of combination chemotherapy including cyclophosphamide, cytosine arabinoside and vindesine, and thereafter remained in remission. After 12 years, he was referred to our hospital because of fever and malaise. On admission, CBC showed white blood cells 3,000/microliter with 70% myeloblasts and 3% eosinophils. The bone marrow was hypercellular with 95% blasts, which were negative for myeloperoxidase (MPO) staining. Immunophenotype analysis revealed that the cells were positive for CD13, CD19, CD34, HLA-DR and cytoplasmic MPO. CD19-positive AML was diagnosed. Cytogenetic analysis showed 46, XY, t(6;21)(q13;q22), add(7)(q11) in 19 of 20 metaphase spreads. Rearrangement of the AML1 gene at 21q22 and fusion of the BCR/ABL gene could not be detected by fluorescence in situ hybridization analysis. The patient received combination chemotherapy and achieved a complete remission. Chromosome aberrations involving 7q as well as 21q22 suggested that the initial chemotherapy for HES might have been implicated in the pathogenesis of acute leukemia in this case.     

Basophils (Bsp-1+) derive from the leukemic clone in human myeloid leukemias involving the chromosome breakpoint 9q34

The monoclonal antibody (MoAb) Bsp-1 was used to purify basophilic cells from leukemic blood of five patients with Philadelphia chromosome (Ph') positive chronic myeloid leukemia (CML) and two patients with acute myeloid leukemia (AML) characterized by the chromosomal translocation t(6;9)(p23;q34). When cultured, Bsp-1 positive cells from all CML and AML patients showed the same clonal karyotype changes observed in diagnostic buffy coat preparations, indicating that the basophilic cells were of leukemic origin. In contrast, T lymphocytes from four of five CML patients cultured in the presence of interleukin- 2 (IL-2) showed a normal karyotype and were therefore not derived from the leukemic clone. Bsp-1 staining correlated with toluidine blue- positive basophils in chronic phase CML and with toluidine blue- negative blast cells expressing an immature myeloid phenotype in blast crisis CML and AML. Chromosome in situ hybridization showed that the ABL oncogene was translocated from chromosome 9 to chromosome 22 in the CML patients but remained on chromosome 9 in the AML patients. These results indicate that the breakpoint at 9q34 in CML is 5' of ABL, whereas the breakpoint at 9q34 in AML is 3' of ABL. Field inversion gel electrophoresis showed that the 9q34 breakpoint was not within 200 kb 3' of ABL in one of the AML patients, nor was there any rearrangement of the PIM oncogene locus at 6p21.     

The 8;21 chromosome translocation in acute myeloid leukemia is always detectable by molecular analysis using AML1

The AML1 gene was rearranged in leukemic cells with t(8;21)(q22;q22) or its variant, complex t(8;V;21) translocations from 33 acute myeloid leukemia (AML) patients. The AML1 rearrangement was also detected in three AML patients without t(8;21); two had a normal diploid karyotype, and one had a karyotype of 45,X, - X. The AML1 rearrangement in the t(8;21) breakpoint cluster region was not detected in leukemic cells with cytogenetic abnormalities other than t(8;21), or with normal diploidy obtained from 23 AML patients. Because leukemic cells of the five patients with complex t(8;V;21) translocations had a der(8)t(8;21) chromosome with a break in band 8q22 in common, the juxtaposition of the 5' side of AML1 to a predicted counterpart gene located in the breakpoint region of 8q22 may be an essential step in the leukemogenesis of AML with t(8;21). Our findings show that the 8;21 translocation, its variants, and the masked t(8;21) may all be detectable by the Southern hybridization method using the AML1 probes.     

t(8;21) breakpoints on chromosome 21 in acute myeloid leukemia are clustered within a limited region of a single gene, AML1.

The t(8;21)(q22;q22) translocation is a non-random chromosomal abnormality frequently found in patients with acute myeloid leukemia (AML) with maturation (M2 subtype). We report here the cloning of a gene, named AML1, on chromosome 21 that was found to be rearranged in the leukemic cell DNAs from t(8;21) AML patients. The breakpoints in 16 out of 21 patients were clustered within a limited region of AML1, and detailed analysis in 3 patients revealed that the breakpoints occurred in the same intron of the gene. Sequencing of cDNA clones identified a long open reading frame encoding a 250-amino acid protein. Northern blot analysis detected four constant mRNA species in t(8;21) leukemic and normal cells; the largest species was more abundant in the leukemic cells than in normal cells. In addition, two mRNA species limited to the leukemic cells were found. These findings indicate that the AML1 gene may be involved in neoplastic transformation of AML with the t(8;21) translocation.     

Hemophagocytosis by leukemic blasts in a case of acute megakaryoblastic leukemia with t(16;21)(p11;q22).

We report the case of a 2-year-3-month-old boy with acute megakaryoblastic leukemia showing hemophagocytosis by leukemic blasts. The chromosome analysis of his bone marrow revealed t(16;21)(p11;q22). In addition to the present case, we found 4 other acute myeloid leukemia (AML) cases associated with hemophagocytosis and t(16;21)(p11;q22) in the literature, of which 3 were megakaryoblastic. Although the syndrome of AML with FAB-M4/5 morphology, t(8;16)(p11;p13), and erythrophagocytosis is well known, leukemic blasts of FAB-M7 morphology showing t(16;21)(p11;q22) may be underscored for their phagocytic activity.     

In vitro differentiation of leukemic cells to eosinophils in the presence of interleukin-5 in two cases of acute myeloid leukemia with the translocation (8;21)(q22;q22).

We demonstrated the significant eosinophilic growth of leukemic cells in the presence of interleukin-5 (IL-5) in 2 of 15 cases of acute myeloid leukemia. These two cases were M2 (FAB classification) with the translocation (8;21)(q22; q22). Bone marrow examination revealed the rather high percentages (6% and 9%) of atypical eosinophils in the total nucleated bone marrow cells in these two cases. In the remaining 13 cases, eosinophils were less than 2% in the nucleated bone marrow cells. In the methylcellulose culture system, 142 +/- 18 or 54 +/- 2 colonies were formed by 5 x 10(4) mononuclear cells in the presence of IL-5 in these two cases. These colonies mainly comprised mature eosinophils. Eosinophils were confirmed by Biebrich scarlet staining and electron microscopic examination using a specific lectin binding assay. The eosinophilic differentiation and proliferation of leukemic cells were also observed in the liquid culture system. It was shown that eosinophils observed in both systems were derived from leukemic cells using the chromosomal marker of leukemic cells, t(8;21). Leukemic cells also differentiated to neutrophils or both neutrophils and eosinophils in response to granulocyte colony-stimulating factor or interleukin-3, respectively, but did not respond noticeably to granulocyte-macrophage colony-stimulating factor. Although IL-5 acts on normal eosinophil committed precursors as a lineage-specific growth factor, at least some leukemic cells reacted to IL-5 and could proliferate and differentiate along eosinophilic pathway. Our findings suggest that atypical eosinophils observed in the bone marrow were derived from the leukemic clone in two cases of AML.     

The role of an anti-myeloperoxidase antibody in the diagnosis and classification of acute leukaemia: a comparison with light and electron microscopy cytochemistry

The enzyme myeloperoxidase (MPO) is the hallmark of the myeloid lineage. We have analysed the presence of MPO in blasts from 180 cases of acute leukaemia (103 acute myeloid leukaemia (AML) and 77 acute lymphoid leukaemia (ALL) by means of monoclonal antibodies anti-MPO and immunocytochemistry (alkaline phosphatase anti-alkaline phosphatase method). The aim of the study was to investigate the specificity and sensitivity of this marker compared with MPO cytochemistry by light (LM) and electron microscopy (EM), and with the expression of myeloid antigens. Anti-MPO was positive (greater than 3% blasts) in all but one of the 90 AML positive by LM cytochemistry. Of 13 AML cases negative by MPO cytochemistry, six showed 3-10% blasts reactive with anti-MPO and were also positive with antibodies to CD13 and/or CD33. The presence of MPO was confirmed in four of these by EM. The overall positivity of anti-MPO in AML was 92%. Anti-MPO was negative in all but two ALL (6% and 8% positive blasts). The blasts in these two cases were also CD13, CD33 and MPO positive by EM; both were thus reclassified as biphenotypic. Another two ALL reinterpreted as biphenotypic were negative by MPO cytochemistry and anti-MPO but were MPO positive by EM and with CD13 and/or CD33. We conclude that anti-MPO is a sensitive and specific early marker of myeloid blasts and should be incorporated in the routine immunophenotyping of acute leukaemia.     

Distinctive immunophenotypic features of t(8;21)(q22;q22) acute myeloblastic leukemia in children.

Thirty cases of newly diagnosed pediatric acute myeloblastic leukemia (AML) with French-American-British (FAB) M2 morphology were analyzed with cytogenetics and a comprehensive panel of monoclonal antibodies reactive with lymphoid-, natural killer (NK)-cell-, and myeloid-associated antigens. The t(8;21)(q22;q22), or t(8;21;V)(q22;q22;V), translocation was identified in 16 of the 30 cases. Cases with the t(8;21) did not differ significantly from the remaining M2 cases with respect to expression of CD11b, CD13, CD14, CD15, CD33, CD34, CD36, CD41a, CD42b, CDw65, TdT, or HLA-DR. Expression of the B-cell antigen CD19 was detected in 13 of the 16 t(8;21) cases (81%), but in only 1 of the 14 (7%) other M2 cases (P = .00006). Expression of the CD56 NK-cell antigen was also significantly more frequent among t(8;21) cases (63% v 14%; P = .01). Coexpression of CD19 and CD56 was found only in the t(8;21) group (9 of 16 cases, P = .0009). Furthermore, this phenotype was not found in 48 evaluable cases of de novo AML of the FAB M1, M3, M4, M5, or M7 subtypes. The 14 M2 AML cases lacking the t(8;21) commonly expressed CD2 (n = 5) or CD7 (n = 8). However, no case with the t(8;21) expressed either antigen (P = .01 and .0005, respectively). Thus, the t(8;21) biologic subgroup of pediatric M2 AML has distinct immunophenotypic characteristics that distinguish it from other types of de novo AML.     

8;21 translocation and multilineage involvement

The translocation (8;21)(q22;q22) is commonly associated with acute myeloid leukemia (AML) M2 according to the French-American-British (FAB) classification. We describe 11 cases of t(8;21) diagnosed by strict FAB criteria. Six cases were diagnosed as AML M2, 3 cases as AML M4, 1 case as refractory anemia with excess of blasts in transformation, and 1 case as Philadelphia chromosome negative chronic myeloid leukemia in acceleration. Translocation (8;21) could thus occur in a wider variety of hematological abnormalities. Accordingly, we propose that t(8;21) may involve different hemopoietic lineages.     

Prognostic value of lymphocyte surface markers in acute myeloid leukemia.

We studied the expression of cell surface antigens associated with myeloid and lymphoid leukemias on bone marrow-derived blast cells from 339 patients with newly diagnosed de novo acute myeloid leukemia (AML) enrolled on Cancer and Leukemia Group B (CALGB) chemotherapy protocols. Surprisingly, of 211 cases studied for the expression of CD2 (T-cell marker, sheep erythrocyte binding receptor for T lymphocytes) 45 were positive (21%). In addition, of 298 patients studied for CD19 (B-lymphocyte marker), 41 were positive (14%). Overall, of 170 patients studied for both CD2 and CD19, 56 (33%) were positive. Interestingly, central review of the French-American-British (FAB) morphology of the CD2- and CD19-positive cases showed that FAB M3 was twice as frequent, and M4E eight times as frequent compared with the CD2- and CD19-negative cases. Of 22 lymphocyte antigen-positive cases in which cells were available for studies of Ig or T-cell antigen receptor (TCR) gene rearrangement, 20 were germline, one had a rearranged Ig heavy chain gene, and one had rearranged TCR beta and Ig heavy chain genes. The presence of messenger RNA for CD2 was demonstrated in four CD2 surface antigen-positive cases, thus validating the cell surface data. Lymphocyte antigen-positive cases had karyotypes commonly seen in AML; 71% of cases with an abnormal clone had t(8;21)(q22;q22), inversion 16(p13q22), t(15;17)(q22;q12), or t(9;11)(p22;q23). The patients with lymphocyte markers had a significantly higher incidence of these karyotypic abnormalities compared with patients with lymphocyte antigen-negative AML (34% v 15%, P less than .02). When the outcome to therapy of the lymphocyte antigen-positive cases was compared with that for the CD2, CD19-negative cases, we found that the CD2, CD19-positive cases actually had higher complete remission rates (75% v 59%, P = .04), and significantly longer time to failure (P = .02; 32.4% +/- 6.0% v 18.0% +/- 4.1% at 2 years) and overall survival (P = .02; 43.5% +/- 6.3% v 26.0% +/- 4.5% at 2 years). CD2 antigen-positive cases also had a significantly superior survival (P = .02; 43.8% +/- 7.9% v 29.8% +/- 3.8% at 2 years). There were no significant differences (P less than or equal to .05) between the two groups in age, leukocyte count at diagnosis, incidence of extramedullary disease, or FAB classification.(ABSTRACT TRUNCATED AT 400 WORDS)