Immunoarchitecture of the bone marrow in neutropenia: increased HNK-1 + cells define a subset of neutropenic patients

Retrospective Study of T Cell Leukaemia (Large Granular Lymphocyte Variant) in Dogs Associated with Suspected Immune-Mediated Cytopaenia(s) in the Absence of Peripheral Lymphocytosis

Canine chronic large granular lymphocyte (LGL) leukaemia is commonly characterised by moderate to marked lymphocytosis but not neutropaenia. In humans, LGL leukaemia is often associated with autoimmune disorders, including immune-mediated cytopaenias (mainly neutropaenia). This presentation is rare in dogs. The aim of this retrospective study was to describe the clinical characteristics, treatments, and outcomes of dogs with chronic LGL leukaemia with suspected immune-mediated cytopaenia. Six dogs with a median age of 4.5 years (range 2-8 years) were included in the study. The most common presenting signs were pyrexia and lethargy. All dogs had severe neutropaenia (median neutrophil count 0.07 × 10⁹/L), three had thrombocytopaenia (median platelet count 66 × 10⁹/L), and one had anaemia (HCT 0.32 L/L). In all dogs, bone marrow cytology revealed infiltration of granular T lymphocytes; PARR analysis confirmed clonality in four, and bone marrow flow cytometry identified CD3+ CD8+ neoplastic cells in two cases. All patients received systemic chemotherapy, and the cytopaenias resolved after 1-19 weeks. Two dogs were euthanised 133 and 322 days after diagnosis, two were lost to follow-up after 224 and 357 days, and two were alive at 546 and 721 days. A subset of LGL leukaemia in dogs is associated with immune-mediated cytopaenia and has a unique clinical presentation.

Neutropenia and Large Granular Lymphocyte Leukemia: From Pathogenesis to Therapeutic Options

Large granular lymphocyte leukemia (LGLL) is a rare lymphoproliferative disorder characterized by the clonal expansion of cytotoxic T-LGL or NK cells. Chronic isolated neutropenia represents the clinical hallmark of the disease, being present in up to 80% of cases. New advances were made in the biological characterization of neutropenia in these patients, in particular STAT3 mutations and a discrete immunophenotype are now recognized as relevant features. Nevertheless, the etiology of LGLL-related neutropenia is not completely elucidated and several mechanisms, including humoral abnormalities, bone marrow infiltration/substitution and cell-mediated cytotoxicity might cooperate to its pathogenesis. As a consequence of the multifactorial nature of LGLL-related neutropenia, a targeted therapeutic approach for neutropenic patients has not been developed yet; moreover, specific guidelines based on prospective trials are still lacking, thus making the treatment of this disorder a complex and challenging task. Immunosuppressive therapy represents the current, although poorly effective, therapeutic strategy. The recent identification of a STAT3-mediated miR-146b down-regulation in neutropenic T-LGLL patients emphasized the pathogenetic role of STAT3 activation in neutropenia development. Accordingly, JAK/STAT3 axis inhibition and miR-146b restoration might represent tempting strategies and should be prospectively evaluated for the treatment of neutropenic LGLL patients.

Distinct bone marrow findings in T-cell granular lymphocytic leukemia revealed by paraffin section immunoperoxidase stains for CD8, TIA-1, and granzyme B

Unlike other leukemia types in which the bone marrow findings are diagnostic, the bone marrow pathology of T-cell granular lymphocytic leukemia (GLL) is subtle and ill-defined. In this study, bone marrow biopsy specimens from 36 patients with T-cell GLL and from 25 control patients with cytopenias and relative or absolute increases in blood large granular lymphocytes were studied by immunohistochemistry using antibodies to the cytolytic lymphocyte antigens CD8, CD56, CD57, TIA-1, and granzyme B. The goals were to clarify the bone marrow pathology of T-cell GLL and to refine the diagnostic criteria for T-cell GLL. Most bone marrow specimens from the T-cell GLL patients contained interstitially distributed clusters of at least 8 CD8(+) (83%) or TIA-1(+) (75%) lymphocytes or clusters of at least 6 granzyme B(+) (50%) lymphocytes. Interstitial clusters of CD8(+), TIA-1(+), or granzyme B(+) cells were present in 36%, 12%, and 0%, respectively, of the control bone marrows (all values significantly different, P <.001). An additional T-cell GLL disease-specific finding was the presence of linear arrays of intravascular CD8(+), TIA-1(+), or granzyme B(+) lymphocytes, found in 67% of cases of T-cell GLL and in none of the 25 control samples (P <.001). Staining for CD56 and CD57 was noncontributory. These findings clarify the bone marrow histopathology of T-cell GLL and provide an additional tool by which the discrete, abnormal lymphocyte population required for a diagnosis of T-cell GLL can be identified.

Non-immune chronic idiopathic neutropenia of adult: an overview

There is strong evidence that non-immune chronic idiopathic neutropenia of adult is a cytokine-mediated syndrome characterized by (a) neutropenia of varying degree associated with a low number of lineage-specific CD34+ cells and increased production of inhibitors of hematopoiesis, including transforming growth factor-beta1 and tumor necrosis factor-alpha; (b) lymphopenia due to selective loss of primed/memory T-cells and NK cells; (c) increased splenic volume on ultrasonography in 48.1% of patients; (d) osteopenia and/or osteoporosis in 60.0% of patients; (e) anemia, mostly of the type of anemia of chronic disease, in 15.6% of patients; (f) features of chronic antigenic stimulation, including increased proportion of bone marrow plasma cells, increased serum levels of IgG1 and/or IgA, increased frequency of monoclonal gammopathy of undetermined significance, increased frequency of antinuclear antibodies with specific reactivity, and increased serum levels of circulating immune complexes; and (g) increased concentrations of a variety of macrophage-derived pro-inflammatory cytokines and chemokines capable of affecting bone metabolism, bone marrow function, and leukocyte trafficking. All these findings are suggestive of the existence of an unrecognized low-grade chronic inflammatory process which may be involved in the pathogenesis of the disorder. Neutropenia in these patients is probably the result of a combination of at least three factors, reduced neutrophil production in bone marrow, enhanced neutrophil extravasation, and increased sequestration and/or extravasation of neutrophils into the spleen.

Neutropenia associated with X-linked agammaglobulinaemia

In a series of six cases of sex-linked agammaglobulinaemia neutropenia occurred as a presenting feature in four and during the presenting illness in the other two. The six patients all had low antibody titres and absent or low immunoglobulin concentrations with normal concentrations of T cells and absent B cells. The patients were all first seen with severe, acute infection, including septic abscesses and meningitis; neutropenia resolved as the infection and immunoglobulin deficiency were treated. Haematologists should be aware that neutropenia is a common association of infection in patients with immunoglobulin deficiency.

The pathology of large granular lymphocyte leukemia

The authors conducted a histopathologic study on tissues from 11 patients with the recently described syndrome of large granular lymphocyte (LGL) leukemia. Distinctive pathologic findings were found most often in the bone marrow, liver, and spleen. The bone marrow biopsies contained nonparatrabecular lymphoid infiltrates that were nodular or diffuse and interstitial. Plasmacytosis was found and in two cases there was myeloid maturation arrest. The liver biopsies contained sinusoidal and portal infiltrates and the spleen had red pulp cord and sinus infiltrates, plasmacytosis, and follicular hyperplasia. Lymph node involvement was nondiagnostic, consistent with the usual absence of lymphadenopathy. The morphologic findings were sometimes indistinguishable from other reactive or low-grade lymphoproliferative disorders, especially chronic lymphocytic leukemia/well-differentiated lymphocytic lymphoma (CLL/WDLL) and hairy cell leukemia. These results suggest the need to correlate peripheral blood cell counts and morphology as well as immunophenotypic studies with tissue histology to distinguish LGL leukemia from other disorders. Establishing a correct diagnosis of LGL leukemia may help clarify the etiology of unexplained peripheral blood cytopenias, arthritis, and other autoimmune manifestations in individual patients.