Eosinophilic leukaemia: morphological, cytochemical, and electron microscopic studies

ETV6-PDGFRB and FIP1L1-PDGFRA stimulate human hematopoietic progenitor cell proliferation and differentiation into eosinophils: the role of nuclear factor-κB

BACKGROUND

ETV6-PDGFRB (also called TEL-PDGFRB) and FIP1L1-PDGFRA are receptor-tyrosine kinase fusion genes that cause chronic myeloid malignancies associated with hypereosinophilia. The aim of this work was to gain insight into the mechanisms whereby fusion genes affect human hematopoietic cells and in particular the eosinophil lineage.

DESIGN AND METHODS

We introduced ETV6-PDGFRB and FIP1L1-PDGFRA into human CD34(+) hematopoietic progenitor and stem cells isolated from umbilical cord blood.

RESULTS

Cells transduced with these oncogenes formed hematopoietic colonies even in the absence of cytokines. Both oncogenes also stimulated the proliferation of cells in liquid culture and their differentiation into eosinophils. This model thus recapitulated key features of the myeloid neoplasms induced by ETV6-PDGFRB and FIP1L1-PDGFRA. We next showed that both fusion genes activated the transcription factors STAT1, STAT3, STAT5 and nuclear factor-κB. Phosphatidylinositol-3 kinase inhibition blocked nuclear factor-κB activation in transduced progenitor cells and patients' cells. Nuclear factor-κB was also activated in the human FIP1L1-PDGFRA-positive leukemia cell line EOL1, the proliferation of which was blocked by bortezomib and the IκB kinase inhibitor BMS-345541. A mutant IκB that prevents nuclear translocation of nuclear factor-κB inhibited cell growth and the expression of eosinophil markers, such as the interleukin-5 receptor and eosinophil peroxidase, in progenitors transduced with ETV6-PDGFRB. In addition, several potential regulators of this process, including HES6, MYC and FOXO3 were identified using expression microarrays.

CONCLUSIONS

We show that human CD34(+) cells expressing PDGFR fusion oncogenes proliferate autonomously and differentiate towards the eosinophil lineage in a process that requires nuclear factor-κB. These results suggest new treatment possibilities for imatinib-resistant myeloid neoplasms associated with PDGFR mutations.

Chronic eosinophilic leukemia: a case report and review of literature

Chronic Eosinophilic Leukemia (CEL) is a rare type of chronic myeloproliferative disorder of unknown etiology with no available true incidence. The vaguely overlapping clinico - pathological picture of CEL with idiopathic hypereosinophilic syndrome (IHES) often adds to the diagnostic confusion. An evidence of genetic clonality of eosinophils or an increase in blast cells in the blood or bone marrow is mandatory for diagnosis of CEL while no specific diagnostic tests exist for IHES; making it an entity of exclusion. Till date, CEL is a rarely reported entity in India. We add yet another case of eosinophilic leukemia along with review of available literature.

Acute nonlymphocytic leukemia with eosinophilic differentiation

Four cases of de novo acute nonlymphocytic leukemia (ANLL) with early eosinophilic differentiation are described. The clinical course did not differ from that of the usual forms of ANLL. Morphologic and cytochemical features that can support this diagnosis are discussed. Particularly, the cyanide-resistant peroxidase stain appeared to be a specific marker of eosinophilic differentiation. Acute eosinophilic leukemia is a distinct entity, and this unusual subtype of ANLL can be set apart from other forms of ANLL characterized by hypereosinophilia.

Acute myelomonocytic leukaemia with abnormal eosinophils and inversion of chromosome 16

We report a further case of a recently recognized variety of acute myelomonocytic leukaemia (M4 subtype) with bone marrow eosinophilia and inversion of chromosome 16. The eosinophils showed a distinctly abnormal morphology, cytochemical staining and ultrastructure.

The hypereosinophilic syndrome in acute lymphocytic leukemia

A 21-year-old white man presented with marked peripheral blood eosinophilia that later evolved into acute lymphocytic leukemia (FAB2 ALL). He died precipitously from refractory congestive heart failure immediately after antileukemic therapy was started. Autopsy revealed multiorgan infiltration with eosinophils and the typical cardiac findings of Löfflers endocarditis. Clinical and pathologic features of this and the 14 other cases of ALL and the hypereosinophilic syndrome (HES) reported in the English-language literature are described. The eosinophilia in these cases is reactive and resolves with successful leukemia remission induction. Hydroxyurea is effective in rapidly lowering eosinophil counts. Early use of hydroxyurea in this disease may improve patient survival and decrease the risk of sudden cardiac death.

Eosinophilic differentiation of the human promyelocytic leukemia cell line, HL-60

HL-60 promyelocytic leukemia cells differentiated to eosinophils and eosinophilic precursors when cultured under mildly alkaline conditions (pH 7.6-7.8) for 7 d without refeeding. New cytoplasmic granules appeared blue in the least mature cells and red in the most mature cells when stained with Wright-Giemsa. The granules also stained with Luxol-fast-blue, a characteristic of eosinophil granules. Furthermore, most cells contained the eosinophil major basic protein (MBP); the Charcot-Leyden Crystal (CLC) protein (lysophospholipase), eosinophil peroxidase, acid phosphatase, and arylsulfatase were also detected in a portion of these cells. The eosinophil major basic protein was found in a high proportion of undifferentiated cells, and thus may be constituitively produced. By examining finely banded chromosomes, translocation break points were demonstrated at q22 on one chromosome 16 and at q23 on the other homologue; abnormalities in this region of the long arm of 16 are a characteristic finding in the recently described syndrome of acute myelomonocytic leukemia (AMMoL) with abnormal bone marrow eosinophils. In common with the bone marrow eosinophils in these patients, the HL-60 eosinophil granules contained chloroacetate esterase and periodic-acid Schiff (PAS) reactive material; crystalloid inclusions were rare. Therefore, the HL-60 cell line appears to be an in vitro model for eosinophilopoiesis and may be specially suited for the study of the abnormal eosinophils seen in certain malignant conditions.

Eosinophilic blast crisis in a case of chronic myeloid leukaemia

A case of typical chronic myeloid leukaemia (CML) is described, of which the terminal blast crisis was characterized by an impressive proliferation of atypical eosinophils and by the simultaneous complete deficiency of neutrophilic myeloperoxidase. Since eosinophilic cells preserved a strong peroxidase positivity, a high number of immature non-granular eosinophilic precursors could be recognized among the leukaemic blast cells, thus supporting the diagnosis of eosinophilic blast crisis of CML.

Fatal hypereosinophilia with chromosome 15q- in a patient with multiple primary and familial neoplasms

A man with large-cell carcinoma of the lung, cerebral meningioma, occult adenocarcinoma of the prostate, and follicular adenoma of the thyroid developed symptomatic, rapidly progressive hypereosinophilia with abnormalities of eosinophil ultrastructure and bone marrow karyotype (45,X,15q22-). Although the patient's eosinophilia defied strict classification as idiopathic hypereosinophilic syndrome (HES), simple tumor-associated eosinophilia, or eosinophilic leukemia, it appeared to be incited by the lung cancer and quickly acquired malignant independence. The family had an excess of prostate cancer and lymphoproliferative neoplasms.

Bone biopsy in haematological disorders

Bone marrow biopsies are now widely used in the investigation and follow-up of many diseases. Semi-thin sections of 8216 undecalcified biopsies of patients with haematological disorders were studied. Observations were made on the cytopenias and the myelodysplastic syndromes, the acute leukaemias the myeloproliferative disorders, Hodgkin's disease and the malignant lymphomas including multiple myeloma, hairy cell leukaemia and angioimmunoblastic lymphadenopathy. Bone marrow biopsies are essential for the differential diagnosis of most cytopenias and for the early recognition of fibrosis which most frequently occurred as a consequence of megakaryocytic proliferation in the myeloproliferative disorders. Different patterns of bone marrow involvement were found in the lymphoproliferative disorders and both their type and extent constituted factors of prognostic significance. A survey of the literature is given and the conclusion is drawn that bone marrow biopsies provide indispensible information for the diagnostic evaluation and the follow-up of patients with haematological disorders.

A spectrum of hypereosinophilic syndromes exemplified by six cats with eosinophilic enteritis

Of six cats with eosinophilic enteritis, two had lesions confined to the intestinal tract, and four had varied disseminated eosinophilic infiltration of other organs. The lesions in these cats are similar to those of the hypereosinophilic syndrome in man. A feline hypereosinophilic syndrome is proposed, consisting of eosinophilic enteritis, disseminated eosinophilic disease, and eosinophilic leukemia.

The association of eosinophilia with lymphoblastic leukaemia or lymphoma: a study of seven patients

Seven patients with hypereosinophilia in association with a lymphoblastic malignancy are described. The eosinophilia preceded or was present at diagnosis in all patients. Eosinophil counts fell during complete remission but rose significantly before or during relapses in five patients. Hypogranular and sometimes Pelger-eosinophils were seen in five cases. Surface and enzyme markers defined the malignancy in six cases as common-ALL (three), T-ALL (two) and T-lymphoblastic lymphoma (one). Although a diagnosis of eosinophilic leukaemia or acute myeloid leukaemia with eosinophil differentiation was considered in three patients, cytochemical and ultrastructural studies failed to show any evidence of myeloid differentiation in the blast cells. The bone marrow karyotype was normal in the four patients studied. All seven patients had one or more relapses and six died 6-62 months from diagnosis. Severe complications of the hypereosinophilic syndrome developed in one patient. As T-lymphocytes have been shown to be involved in the induction of eosinophilia in rodents, it is suggested that the hypereosinophilia in these patients was induced by eosinopoietic stimuli produced by lymphoblasts.