Chronic eosinophilic leukemia presenting with autoimmune hemolytic anemia and erythrophagocytosis by eosinophils.

Eosinophils function primarily as secretory cells and phagocytosis by eosinophils is rarely seen. We describe a case of chronic eosinophilic leukemia (CEL) in a 72-year-old male with a history of previously treated non-Hodgkin's lymphoma (NHL) presenting with erythrophagocytosis by eosinophils and an associated autoimmune hemolytic anemia (AIHA). This patient did not show evidence of relapsed NHL. The patient's blood showed a markedly elevated eosinophil count of 16 x 10(9)/L [normal 0-0.45 x 10(9)/L] on a background of myelodysplasia and features of AIHA. Prominent erythrophagocytosis by eosinophils was visualized in the blood and in the bone marrow. Numerous Charcot-Leyden crystals were also seen in the bone marrow amid increased numbers of eosinophils and the presence of dysplastic granulopoiesis. AIHA is rarely described in the setting of CEL. More significantly, this represents the first case report to describe erythrophagocytosis by eosinophils.

CD34-positive acute promyelocytic leukemia is associated with leukocytosis, microgranular/hypogranular morphology, expression of CD2 and bcr3 isoform.

Acute promyelocytic leukemia (APL) has a favorable prognosis. Current therapy includes chemotherapy used in combination with all-trans-retinoic acid (ATRA). Although the differentiating effects of ATRA on promyelocytes have been well established, in vitro studies have shown that less-differentiated APL blasts (CD34(+)) demonstrate a variable responsiveness to ATRA. To assess the clinical relevance of this finding, we analyzed a cohort of 38 patients with t(15;17) and/or PML-RARalpha APL to determine the incidence and laboratory features of CD34(+) APL. Thirty-two percent (12/38) of cases were CD34(+). There was a difference in WBC at presentation between CD34(+) and CD34(-) cases (34.6 +/- 9.2, mean +/- standard error vs. 5.4 +/- 2.0, P = 0.009). Patients with CD34(+) APL demonstrated a micro/hypogranular phenotype (75%) (P = 0.001), co-expression of CD2(+) (83%) (P = 0.001), and the bcr3 isoform (100%) (P = 0.017). In contrast, CD34(-) cases demonstrated hypergranular morphology (65%), CD2(+) (15%), and the bcr1 isoform (50%). A high presenting WBC count (\G10 x 10(9)/L) was associated with an inferior overall survival (Log rank = 0.0047). Patients with CD34(+) APL demonstrated an incidence of early mortality of 50%. Despite a marked correlation between CD34 positivity and increased WBC count, overall survival of CD34(+) and CD34(-) cases did not differ significantly in our small cohort. Immunophenotypic analysis for CD34 expression should be included in future large APL trials to determine if detection of CD34(+) blasts represents an independent adverse prognostic factor.

Morphology of acute promyelocytic leukemia with cytogenetic or molecular evidence for the diagnosis: characterization of additional microgranular variants.

Early diagnosis of t(15;17) acute promyelocytic leukemia (APL) is essential because of the associated disseminated intravascular coagulation and the unique response of the disease to all-trans retinoic acid (ATRA) therapy. Early diagnosis depends primarily on morphological recognition. The French-American-British (FAB) classification, however, does not describe all morphological variations that occur in APL. In 25 cases with evidence of APL confirmed by cytogenetic and/or molecular analysis, we found a heterogeneous morphological group. The most common form of APL was heterogeneous and consisted of various combinations of cells in which hypergranular cells and some cells with multiple Auer rods were obvious. In some cases, one cell predominated. This led to the description of five subcategories. These included the classical FAB M3 with hypergranular cells and multiple Auer rods; the FAB variant with hypogranular bilobed cells; the basophilic cell type of McKenna et al. [Br. J. Haematol 50:201, 1982]; and two additional subtypes, one consisting of differentiated promyelocytes and a few blast cells (M2-like), and the other consisting largely of blast cells and a few early promyelocytes (M1-like). Immunophenotyping revealed a pattern of CD33 and/or CD13 positivity, and CD14 and HLA-DR negativity in 96% of cases. CD2 was positive in the FAB variant and in the subtype with basophilic cells, but negative with other subtypes. Three out of five cases with basophilic cell predominance [McKenna et al.: Br J Haematol 50:201, 1982], and one out of two M2-like cases, responded to ATRA therapy. Awareness of the heterogeneity and the atypical morphologic subtypes found in t(15;17) APL will contribute to improved recognition and early institution of ATRA therapy.

Monoclonal antibodies in the management of acute leukemia.

This report reviews the diagnostic significance of immune markers, their relationship to patient outcome, and the therapeutic uses of monoclonal antibodies (MoAbs) in acute leukemia. Immunophenotyping allows for rapid and reproducible diagnosis in the majority of cases of acute leukemia. It is of particular importance in recognizing the major immunologic subclasses of acute lymphoblastic leukemia (ALL), and in identifying subtypes of acute myeloblastic leukemia (AML) which cannot be differentiated by morphology and cytochemistry alone, such as FAB M0 or M7. Immune marker analysis has been used to detect minimal residual disease in patients' bone marrow and CSF after treatment. However, the presence of leukemia-associated phenotypes on small numbers of normal cells may reduce the sensitivity of detection in some cases. The prognostic value of immune markers in AML is limited. In ALL, the prognostic significance of the different immunophenotypic subtypes has been lessened by modern treatment protocols. The relationship of mixed-lineage or biphenotypic antigen expression to patient outcome in both AML and ALL is unclear. Therapeutic applications of MoAbs in acute leukemia include immunologic techniques for purging malignant cells from autografts prior to transplantation, T-lymphocyte depletion from allografts as a strategy to reduce graft-versus-host disease, and the use of flow cytometry to monitor the timing and extent of leukapheresis in peripheral stem cell transplantation. MoAbs have also enabled the recent development of transplantation protocols using positively-selected CD34+ stem cells.

CD2+, CD3-, CD56/NCAM+ malignant lymphoma with TCR beta gene rearrangement: a case report.

A case of CD56/NCAM+ malignant lymphoma is reported. Only a rare malignant lymphoma cell showed azurophilic granules in the cytoplasm of Giesma-stained preparations, while electron microscopic examination revealed occasional cytoplasmic granules with paracrystalline inclusions. The most common phenotype seen in NK lymphomas, CD2+, CD3-, CD56+, CD16-, CD57-, was present in the case. Cases with this phenotype have been interpreted to represent either true NK lymphoma or T-cell lymphoma with NK expression. Genotyping, where performed, has shown TCR germline configuration. Our case showed TCR beta rearrangement indicating that the above phenotype can be associated with a peripheral T-cell lymphoma.

A case of CD3+, CD4-, CD8-, WT31- acute T-cell leukemia.

The article reports a case of acute T-cell leukemia (T-ALL) with the unusual CD3+, WT31 phenotype. On surface marker analysis, the blast cells were found to be CD7+, CD2-, CD5-, CD1-, CD4-, CD8-, CD3+ and negative for B-lymphoid and myeloid lineage. The cells had both TCR beta and TCR gamma gene rearrangement but had negative results with the monoclonal antibody WT31, which reacts with a framework epitope on the T alpha/beta heterodimer (Ti) of the conventional T-cell receptor (TCR). This suggests an association of the CD3 molecular complex with a different polypeptide (the alternate TCR gamma). In two similar reported cases of T-ALL (WT31-, CD3+, CD4-, CD8-), the CD3 molecular complex was found to be associated with a product of the T gamma gene.

Distribution of a hematopoietic-specific differentiation antigen of K562 cells in the human myeloid and lymphoid cell lineages.

BALB/c mice were immunized with uninduced K562 erythroleukemia cells and hybridomas were isolated after fusion of immune spleen cells to P3/NS1 murine myeloma cells. One selected hybrid, designated 10L-30, secreted an antibody of subclass immunoglobulin G2a which was specific for hematopoietic cells. Analysis of 10L-30 binding by complement-mediated cytotoxicity, indirect immunofluorescence, solid-phase radioimmunoassay, and mixed hemadsorption assay indicated that the 10L-30 antigen was expressed on the myeloid cell lines K562, KG-1A, KG-1, some B- and T-lymphoid cell lines, and all normal human peripheral blood T-lymphocyte samples tested, but was absent on the more differentiated myeloid cell lines HL-60, ML-2, ML-3, and normal blood granulocytes. Induction of erythroid differentiation in hemin-treated K562 cells caused a 10-fold reduction in 10L-30 binding. Human erythroid and granulocytic progenitor cells, platelets, erythrocytes, and reticulocytes were nonreactive, as were a variety of nonhematopoietic human tumor cell lines. Freshly isolated leukemic bone marrow samples from patients with M5 (2 of 5), M6 (2 of 2), acute lymphoid leukemia (9 of 14), and chronic myeloid leukemia in lymphoid blast crisis (1 of 1) were 10L-30 positive. The combined evidence indicates that the 10L-30 antigen is a normal, hematopoietic-specific differentiation antigen which is strongly expressed on both immature cells of the myeloid lineage and more generally in lymphoid ontogeny. The 10L-30 antigen may be a useful marker of both normal and leukemic hematopoietic differentiation.

Classifying acute leukemia by immunophenotyping: a combined FAB-immunologic classification of AML.

A panel of commercially available monoclonal antibodies and five heteroantisera were used to distinguish and subtype 138 cases of acute leukemia (AL). The immunophenotype was compared with the French-American-British (FAB) classification obtained on the cases. The immunophenotype discriminated acute myelogenous leukemia (AML) from acute lymphoblastic leukemia (ALL) and recognized cases not distinguished by cytochemistry (22% of cases), mixed lineage phenotypes (13% of cases), and cases with separate populations of lymphoblasts and myeloblasts (one case). Using the immunologic panel and derived criteria to subtype AML, correspondence of the immunophenotype to the FAB subtypes M1, M2, M4, and M5 was possible in greater than 80% of cases. A combined classification of the immunophenotype and FAB morphology/cytochemistry was devised for AML subtyping. It is recommended that immunophenotyping should be done at least in all cases with negative or inconclusive cytochemistry. At present, we suggest that until a "gold standard" for identifying leukemic subtypes is developed, the best method for typing acute leukemia is by using a combination of morphology, cytochemistry and immunophenotyping.

The contribution of cytochemistry and immunophenotyping to the reproducibility of the FAB classification in acute leukemia.

Intraobserver and interobserver reproducibility of the FAB classification was assessed for two independent observers whose decisions are acted on for treatment of patients with acute leukemia in the Hamilton region. Intraobserver reproducibility was assessed for Wright-stained preparations that were examined independently on two consecutive occasions at least 2 weeks apart. A third reading was performed with Wright stain and cytochemical data, and the fourth reading was done with addition of immunophenotype data. Concordance was calculated using a statistic that corrects for chance-expected agreement (k), and a weighted statistic that takes into account the seriousness of disagreements was used. Samples were available for morphological and cytochemical assessment on 105 patients, and immunophenotype data were available on 93 specimens. Intraobserver concordance was 64.8% and 70.5% for observers A and B, respectively, with kappa values of .56 and .62. There were 37 discordant readings for observer A and 31 for observer B, with each observer discordant between lymphocytic:nonlymphocytic phenotypes in ten cases. Concordance between observers was 63% (k = .54) and 72% (k = .65) for each of two separate readings for Wright-stained preparations only. Reproducibility improved to 89% (k = .86) when cytochemistry was added. When immunophenotype information was provided in addition to Wright-stained and cytochemical preparations, the agreement was 99%. Lymphocytic:nonlymphocytic discordance between observers occurred on nine occasions when Wright-stained preparations only were available and four times when cytochemistry was added; it did not occur with immunophenotyping. The study suggests that immunophenotyping, when added to morphological assessment of acute leukemia, may contribute substantially to agreement between observers.

Simultaneous or sequential expression of lymphoid and myeloid phenotypes in acute leukemia.

Acute mixed myeloid-lymphoid leukemia is uncommon. We report four cases in which myeloid and lymphoid cell markers were observed simultaneously or sequentially when 94 patients with acute leukemia were phenotyped according to the French-American-British (FAB) classification system, with cytochemical stains, and with immunologically defined differentiation markers (identified by monoclonal antibodies and antiterminal deoxynucleotidyl transferase [TdT]). In one case, conversion from acute lymphoblastic leukemia to acute myeloid leukemia was noted (FAB L1, TdT+ to FAB M4, Auer rods, TdT-). In another patient, two distinct populations of myeloid and lymphoid blast cells were observed simultaneously (TdT-, LeuM1+/TdT+, LeuM1-). In two additional patients, acute leukemia was characterized by the expression of both lymphoid and myeloid markers on the same cell (TdT+/Leu M1+, B4+/Leu M1+ and greater than or equal to 70% TdT+, T11+, My9+). The Philadelphia (Ph1) chromosome was negative in all cases, though other chromosomal abnormalities were noted in three out of four cases. Malignant transformation of a pluripotential stem cell for both lymphoid and myeloid lineages, with or without the Ph1 chromosome marker, could explain the coexistence of distinct populations of lymphoblasts and myeloblasts in acute leukemia. Acute leukemia with a biphenotypic profile may reflect genome depression accompanying neoplasia.