Seroreactivity to LGL leukemia-specific epitopes in aplastic anemia, myelodysplastic syndrome and paroxysmal nocturnal hemoglobinuria: results of a bone marrow failure consortium study

Large Granular Lymphocytic Leukemia: Clinical Features, Molecular Pathogenesis, Diagnosis and Treatment

Large granular lymphocytic (LGL) leukemia is a lymphoproliferative disorder characterized by persistent clonal expansion of mature T- or natural killer cells in the blood via chronic antigenic stimulation. LGL leukemia is associated with specific immunophenotypic and molecular features, particularly STAT3 and STAT5 mutations and activation of the JAK-STAT3, Fas/Fas-L and NF-κB signaling pathways. Disease-related deaths are mainly due to recurrent infections linked to severe neutropenia. The current treatment is based on immunosuppressive therapies, which frequently produce unsatisfactory long-term responses, and for this reason, personalized approaches and targeted therapies are needed. Here, we discuss molecular pathogenesis, clinical presentation, associated autoimmune disorders, and the available treatment options, including emerging therapies.

Large granular lymphocyte leukemia: An indolent clonal proliferative disease associated with an array of various immunologic disorders

Large granular lymphocyte leukemia (LGLL) is a chronic lymphoproliferative disorder characterized by the proliferation of T or NK cytotoxic cells in the peripheral blood, the spleen and the bone marrow. Neutropenia leading to recurrent infections represents the main manifestation of LGLL. One specificity of LGLL is its frequent association with auto-immune disorders, among them first and foremost rheumatoid arthritis, and other hematologic diseases, including pure red cell aplasia and bone marrow failure. The large spectrum of manifestations and the classical indolent course contribute to the diagnosis difficulties and the frequency of underdiagnosed cases. Of importance, the dysimmune manifestations disappear with the treatment of LGLL as the blood cell counts normalize, giving a strong argument for a pathological link between the two entities. The therapeutic challenge results from the high rate of relapses following the first line of immunosuppressive drugs. New targeted agents, some of which are currently approved in autoimmune diseases, appear to be relevant therapeutic strategies to treat LGLL, by targeting key activated pathways involved in the pathogenesis of the disease, including JAK-STAT signaling.

LGL Clonal Expansion and Unexplained Cytopenia: Two Clues Don't Make an Evidence

Clonal expansions of large granular lymphocytes (LGL) have been reported in a wide spectrum of conditions, with LGL leukemia (LGLL) being the most extreme. However, the boundaries between LGLL and LGL clones are often subtle, and both conditions can be detected in several clinical scenarios, particularly in patients with cytopenias. The intricate overlap of LGL clonal expansion with other disease entities characterized by unexplained cytopenias makes their classification challenging. Indeed, precisely assigning whether cytopenias might be related to inadequate hematopoiesis (i.e., LGL as a marginal finding) rather than immune-mediated mechanisms (i.e., LGLL) is far from being an easy task. As LGL clones acquire different pathogenetic roles and relevance according to their diverse clinical settings, their detection in the landscape of bone marrow failures and myeloid neoplasms has recently raised growing clinical interest. In this regard, the current availability of different diagnostic techniques, including next generation sequencing, shed light on the relationship between LGL clones and cytopenias, paving the way towards a better disease classification for precision medicine treatments. Herein, we discuss the clinical relevance of LGL clones in the diagnostic algorithm to be followed in patients presenting with cytopenias, offering a foundation for rational management approaches.

Lack of Viral Load Within Chronic Lymphoproliferative Disorder of Natural Killer Cells: What Is Outside the Leukemic Clone?

Large granular lymphocyte leukemias (LGLL) are sustained by proliferating cytotoxic T cells or NK cells, as happens in Chronic Lymphoproliferative Disorder of Natural Killer cells (CLPD-NK), whose etiology is only partly understood. Different hypotheses have been proposed on the original events triggering NK cell hyperactivation and transformation, including a role of viral agents. In this perspective, we revise the lines of evidence that suggested a pathogenetic role in LGLL of the exposure to retroviruses and that identified Epstein Barr Virus (EBV) in other NK cell leukemias and lymphomas and focus on the contrasting data about the importance of viral agents in CLPD-NK. EBV was detected in aggressive NK leukemias but not in the indolent CLPD-NK, where seroreactivity against HTLV-1 retrovirus envelope BA21 protein antigens has been reported in patients, although lacking clear evidence of HTLV infection. We next present original results of whole exome sequencing data analysis that failed to identify viral sequences in CLPD-NK. We recently demonstrated that proliferating NK cells of patients harbor several somatic lesions likely contributing to sustain NK cell proliferation. Thus, we explore whether "neoantigens" similar to the BA21 antigen could be generated by aberrancies present in the leukemic clone. In light of the literature and new data, we evaluated the intriguing hypothesis that NK cell activation can be caused by retroviral agents located outside the hematopoietic compartment and on the possible mechanisms involved with the prospects of immunotherapy-based approaches to limit the growth of NK cells in CLPD-NK disease.

Retroviral sero-reactivity in LGL leukaemia patients and family members

T-cell large granular lymphocyte (T-LGL) leukaemia is characterized by a clonal proliferation of cytotoxic T cells and is frequently associated with rheumatoid arthritis. Sera from some LGL leukaemia patients react to a portion of the human T-cell leukaemia virus (HTLV-1/2) transmembrane envelope protein, BA21, although HTLV-1/2 infection is rare in LGL leukaemia patients. Here we show that family members, including spouses, of an LGL leukaemia patient had elevated LGL counts, BA21 reactivity and, additionally, recognition of HIV-1 gp41. Thus, both LGL leukaemia patients and clinically normal contacts sharing the same environment have evidence of exposure to a retrovirus.

Frequent STAT3 mutations in CD8+ T cells from patients with pure red cell aplasia

Dysregulation of T-cell-mediated immunity is responsible for acquired pure red cell aplasia (PRCA). Although STAT3 mutations are frequently detected in patients with T-cell large granular lymphocytic leukemia (T-LGLL), which is often complicated by PRCA and which is also reported to be associated with acquired aplastic anemia (AA) and myelodysplastic syndrome (MDS), whether STAT3-mutated T cells are involved in the pathophysiology of PRCA and other types of bone marrow failure remains unknown. We performed STAT3 mutation analyses of the peripheral blood mononuclear cells from PRCA patients (n = 42), AA (n = 54), AA-paroxysmal nocturnal hemoglobinuria (AA-PNH; n = 7), and MDS (n = 21) using an allele-specific polymerase chain reaction and amplicon sequencing. STAT3 mutations were not detected in any of the 82 patients with AA/PNH/MDS but were detected in 43% of the 42 PRCA patients. In all 7 STAT3-mutation-positive patients who were studied, the STAT3 mutations were restricted to sorted CD8⁺ T cells. The prevalence of STAT3 mutation in idiopathic, thymoma-associated, autoimmune disorder-associated, and T-LGLL-associated PRCA was 33% (5 of 15), 29% (2 of 7), 20% (1 of 5), and 77% (10 of 13), respectively. The STAT3-mutation-positive patients were younger (median age, 63 vs 73 years; P= .026) and less responsive to cyclosporine (46% [6 of 13] vs 100% [8 of 8]; P= .0092) in comparison with STAT3-mutation-negative patients. The data suggest that STAT3-mutated CD8⁺ T cells may be closely involved in the selective inhibition of erythroid progenitors in PRCA patients.

Retrovirus insertion site analysis of LGL leukemia patient genomes

Background

Large granular lymphocyte (LGL) leukemia is an uncommon cancer characterized by sustained clonal proliferation of LGL cells. Antibodies reactive to retroviruses have been documented in the serum of patients with LGL leukemia. Culture or molecular approaches have to date not been successful in identifying a retrovirus.

Methods

Because a retrovirus must integrate into the genome of an infected cell, we focused our efforts on detecting a novel retrovirus integration site in the clonally expanded LGL cells. We present a new computational tool that uses long-insert mate pair sequence data to search the genome of LGL leukemia cells for retrovirus integration sites. We also utilize recently published methods to interrogate the status of polymorphic human endogenous retrovirus type K (HERV-K) provirus in patient genomes.

Results

Our data show that there are no new retrovirus insertions in LGL genomes of LGL leukemia patients. However, our insertion call tool did detect four HERV-K provirus integration sites that are polymorphic in the human population but absent from the human reference genome, hg19. To determine if the prevalence of these or other polymorphic proviral HERV-Ks differed between LGL leukemia patients and the general population, we used a recently developed tool that reports sites in the human genome occupied by a known proviral HERV-K. We report that there are significant differences in the number of polymorphic HERV-Ks in the genomes of LGL leukemia patients of European origin compared to individuals with European ancestry in the 1000 genomes (KGP) data.

Conclusions

Our study confirms that the clonal expansion of LGL cells in LGL leukemia is not driven by the integration of a new infectious or endogenous retrovirus, although we do not rule out that these cells are responding to retroviral antigens produced in other cell types. However, our computational analyses revealed that the genomes of LGL leukemia patients carry a higher burden of polymorphic HERV-K proviruses compare to individuals from KGP of European ancestry. Our research emphasizes the merits of comprehensive genomic assessment of HERV-K in cancer samples and suggests that further analyses to determine contributions of HERV-K to LGL leukemia are warranted.

Electronic supplementary material

The online version of this article (10.1186/s12920-019-0549-9) contains supplementary material, which is available to authorized users.

Clinical Features, Pathogenesis, and Treatment of Large Granular Lymphocyte Leukemias

Large granular lymphocytes (LGLs) are large lymphocytes with azurophilic granules in their cytoplasm. LGLs are either natural killer (NK) cells or T lymphocytes. Expansions of the LGLs in the peripheral blood are seen in various conditions, including three clonal disorders: T-cell LGL (T-LGL) leukemia, chronic lymphoproliferative disorders of NK cells (CLPD-NK), and aggressive NK-cell leukemia (ANKL). However, the monoclonal and polyclonal expansion of LGLs has been associated with many other conditions. The present article describes these LGL disorders, with special emphasis on the clinical features, pathogenesis, and treatments of the three above-mentioned clonal disorders.

Distinct effect of cyclophosphamide and cyclosporine on pure red cell aplasia associated with T-cell large granular lymphocyte leukemia

Large granular lymphocyte (LGL) leukemia is characterized by a clonal proliferation of large-sized lymphocytes with prominent large azurophilic cytoplasmic granules. Although most cases of T-LGL leukemia are indolent and asymptomatic during the course of the disease, some present with pure red cell aplasia (PRCA) and require therapy. We here reported a case of T-LGL leukemia complicated by PRCA in which anemia was resistant to cyclosporine and had been controlled for several years by cyclophosphamide; however, progressive anemia developed despite the administration of cyclophosphamide, but was ameliorated by the re-administration of cyclosporine. The present case demonstrated the 3 different phases of T-LGL proliferation associated with anemia (1st, T-LGL leukemia; 2nd, polyclonal T-LGL expansion; 3rd, myelodysplastic syndrome). We also showed that cyclophosphamide was effective when PRCA was caused by increased numbers of LGL, whereas cyclosporine was administered when hypoplastic myelodysplastic syndrome was suspected as the main cause of anemia. Repetitive bone marrow examinations should be performed throughout the course of T-LGL in order to monitor combined myelodysplastic syndrome.

A paroxysmal nocturnal haemoglobinuria progress with waldenström macroglobulinemia along with T cell monoclonal expansion

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hematopoietic stem cell clinical disease, which has been reported associated with T cell monoclonal expansion and plasma cell dyscrasias. There we reported a case with a 20-year clinical history of PNH. Lately diagnosis of Waldenström macroglobulinemia with the offered evidences of bone marrow examination, flow cytometry and immunofixation electrophoresis. T cell monoclonal expansion was established by polymerase chain reaction. Meanwhile the decreased expression of CD55 and CD59 on neutrophils and erythrocyte were obvious observed. Here we describe the diagnostic evaluation of this patient and provide a brief review of such clonal disorder.