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Funding Information: This project was funded by the European Research Council (Project: M-IMM 647355), Academy of Finland Heal-Art consortium (314442), and ERA PerMed (JAKSTAT-TARGET consortium), Sigrid Juselius Foundation, Signe and Ane Gyllenberg Foundation, Helsinki Institute for Life Science, Cancer Foundation Finland, and Ministry of Education, Culture, Sports, Science and Technology of Japan (Kaken 20K08709). J.H. was supported by Finnish Hematology Association, Blood Disease Research Foundation, Helsinki Institute for Life Science, Biomedicum Helsinki Foundation, Finnish Medical Foundation. T.L. was supported by Academy of Finland (Decision 311081). RZ was supported by Italian Association for Cancer Research (AIRC #20216).?F.I. was supported by KAKEN 20K08709. from Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan. Single-cell RNA sequencing and amplicon sequencing were performed at the Institute for Molecular Medicine Finland FIMM Technology Centre and Finnish Functional Genomics Centre, Turku Bioscience, which are supported by Biocenter Finland. We acknowledge Jay Klievink, Sofie Lundgren, Anita Kumari, and Ella Piekkari for the processing of samples from healthy controls. We acknowledge Emmi Rehn for providing a modified script of GLIPH that was used for the previous version of the findings. We acknowledge the computational resources provided by the Aalto Science-IT project. Funding Information: This project was funded by the European Research Council (Project: M-IMM 647355), Academy of Finland Heal-Art consortium (314442), and ERA PerMed (JAKSTAT-TARGET consortium), Sigrid Juselius Foundation, Signe and Ane Gyllenberg Foundation, Helsinki Institute for Life Science, Cancer Foundation Finland, and Ministry of Education, Culture, Sports, Science and Technology of Japan (Kaken 20K08709). J.H. was supported by Finnish Hematology Association, Blood Disease Research Foundation, Helsinki Institute for Life Science, Biomedicum Helsinki Foundation, Finnish Medical Foundation. T.L. was supported by Academy of Finland (Decision 311081). RZ was supported by Italian Association for Cancer Research (AIRC #20216). F.I. was supported by KAKEN 20K08709. from Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan. Single-cell RNA sequencing and amplicon sequencing were performed at the Institute for Molecular Medicine Finland FIMM Technology Centre and Finnish Functional Genomics Centre, Turku Bioscience, which are supported by Biocenter Finland. We acknowledge Jay Klievink, Sofie Lundgren, Anita Kumari, and Ella Piekkari for the processing of samples from healthy controls. We acknowledge Emmi Rehn for providing a modified script of GLIPH that was used for the previous version of the findings. We acknowledge the computational resources provided by the Aalto Science-IT project. Funding Information: T.L. is a member of the scientific advisory boards and hold stock options of Keystone Nano, Dren Bio, and Kymera Therapeutics (not related to this project). S.M. has received honoraria and research funding from BMS and research funding from Novartis and Pfizer (not related to this project). The remaining authors declare no competing interests. Publisher Copyright: © 2022, The Author(s). T cell large granular lymphocytic leukemia (T-LGLL) is a rare lymphoproliferative disorder of mature, clonally expanded T cells, where somatic-activating STAT3 mutations are common. Although T-LGLL has been described as a chronic T cell response to an antigen, the function of the non-leukemic immune system in this response is largely uncharacterized. Here, by utilizing single-cell RNA and T cell receptor profiling (scRNA+TCRαβ-seq), we show that irrespective of STAT3 mutation status, T-LGLL clonotypes are more cytotoxic and exhausted than healthy reactive clonotypes. In addition, T-LGLL clonotypes show more active cell communication than reactive clones with non-leukemic immune cells via costimulatory cell–cell interactions, monocyte-secreted proinflammatory cytokines, and T-LGLL-clone-secreted IFNγ. Besides the leukemic repertoire, the non-leukemic T cell repertoire in T-LGLL is also more mature, cytotoxic, and clonally restricted than in other cancers and autoimmune disorders. Finally, 72% of the leukemic T-LGLL clonotypes share T cell receptor similarities with their non-leukemic repertoire, linking the leukemic and non-leukemic repertoires together via possible common target antigens. Our results provide a rationale to prioritize therapies that target the entire immune repertoire and not only the T-LGLL clonotype.

T-cell large granular lymphocyte leukemia (T-LGLL) is a lymphoproliferative disease and bone marrow failure syndrome which responds to immunosuppressive therapies. We show single-cell TCR coupled with RNA sequencing of CD3+ T cells from 13 patients, sampled before and after alemtuzumab treatments. Effector memory T cells and loss of T cell receptor (TCR) repertoire diversity are prevalent in T-LGLL. Shared TCRA and TCRB clonotypes are absent. Deregulation of cell survival and apoptosis gene programs, and marked downregulation of apoptosis genes in CD8+ clones, are prominent features of T-LGLL cells. Apoptosis genes are upregulated after alemtuzumab treatment, especially in responders than non-responders; baseline expression levels of apoptosis genes are predictive of hematologic response. Alemtuzumab does not attenuate TCR clonality, and TCR diversity is further skewed after treatment. Inferences made from analysis of single cell data inform understanding of the pathophysiologic mechanisms of clonal expansion and persistence in T-LGLL.

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.

International audience; [No abstract available]

Background: T-cell large granular lymphocyte (LGL) leukemia is a rare lymphoproliferative disease. It frequently involves the expansion of CD8+ cells, which may lead to cytopenias and often correlates with autoimmune disorders. Another form is the CD4+ LGL leukemia, which behaves more indolently but may associate with other neoplasia. Material and Methods: Retrospective and descriptive analysis of the 14 patients diagnosed with T-cell LGL leukemia in our center between 2002 and 2016, regarding gender/age; clinical presentation; immunophenotype; frequency of cytopenias; coexistent malignancies; autoimmune disorders and temporal relationship between both diagnosis; immunosuppressant treatment and its outcome. Results: Three patients had CD4+ LGL leukemia and eleven had CD8+ LGL leukemia. In the latter, neutropenia was the prevailing cytopenia (63.6%), followed by anemia (45.5%) and thrombocytopenia (36.4%). The most common symptoms were fatigue and recurrent bacterial infections; 35.7% presented with asymptomatic cytopenias. From patients with CD4+ LGL leukemia, one had colorectal cancer. Prevalence of autoimmune diseases was 35.7%; its diagnosis preceded the identification of LGL leukemia in all patients. Five patients required treatment; methotrexate was the most selected firstline immunosuppressant. Complete hematological response was achieved in two cases. Mortality rate was 14.3% at a median follow-up time of 2 years. Discussion and Conclusion: Clinical presentation and frequency of cytopenias were close to described in previous studies. The recurrent association with autoimmunity suggests the existence of common etiopathogenic features; chronic autoantigen stimulation might play a role in the onset of the clonal disease. Further studies are needed for determining the gold-standard approach of LGL leukemia. Introdução: A leucemia de grandes linfócitos granulares (LGL) de células T é uma doença linfoproliferativa rara. Esta envolve frequentemente a expansão de células CD8+, podendo levar a citopenias e correlacionar-se com distúrbios autoimunes. Outra forma, a leucemia LGL-CD4+, apresenta um comportamento mais indolente, mas pode associar-se a outras neoplasias. Material e Métodos: Estudo retrospetivo e descritivo dos 14 doentes diagnosticados com leucemia LGL de células T no nosso centro entre 2002 e 2016, avaliando: género/idade; apresentação clínica; imunofenotipagem; frequência de citopenias; neoplasias coexistentes; doenças autoimunes e relação temporal entre diagnósticos; tratamento imunossupressor e seu resultado. Resultados: Três doentes tinham leucemia LGL-CD4+ e onze tinham leucemia LGL-CD8+. Nestes últimos, a neutropenia foi a citopenia mais prevalente (63,6%), seguida da anemia (45,5%) e trombocitopenia (36,4%). Os sintomas mais frequentes foram fadiga e infeções bacterianas recorrentes; 35,7% apresentavam citopenias assintomáticas. Dos doentes com leucemia LGL-CD4+, um apresentava neoplasia do cólon. A prevalência de doenças autoimunes foi 35,7%; este diagnóstico precedeu sempre o da leucemia. Cinco doentes iniciaram terapêutica; o metotrexato foi o imunossupressor de primeira linha mais utilizado. Verificou-se resposta hematológica completa em dois casos. A taxa de mortalidade foi de 14,3%, num seguimento mediano de 2 anos. Discussão e Conclusão: A apresentação clínica e a frequência de citopenias foram semelhantes ao descrito em estudos anteriores. A recorrente associação com autoimunidade sugere a existência de mecanismos etiopatogénicos comuns; a estimulação crónica por autoantigénios poderá desempenhar um papel no desencadear da doença clonal. São necessários mais estudos para determinar a abordagem gold-standard desta patologia.

In recent years, it has become clear that members of the signal transducer and activator of transcription (STAT) family of genes play an important role in cancer. The STAT family consists of seven genes, STAT1-4, STAT5A, STAT5B and STAT6, that are involved in regulating cellular proliferation, apoptosis, angiogenesis and the immune system response. Constitutive activation of STAT3, via mutational changes, is important in oncogenesis in both solid and hematopoietic cancers. In the case of hematopoietic neoplasms, STAT3 driver mutations have been described in T-cell large granular lymphocytic (T-LGL) leukemia and chronic natural killer lymphoproliferative disorders (CLPD-NK) and are seen in 30%-40% of T-LGL leukemia patients. STAT5B is also mutated in T-LGL leukemia and CLPD-NK, but in a much smaller proportion. Here we review past and current research on STAT genes in hematopoietic and solid cancers with emphasis on STAT3 and STAT5B and their roles in the pathogenesis of hematopoietic malignancies, particularly T-LGL leukemia and CLPD-NK.

Letter to the Editor. Large granular lymphocyte (LGL) leukemia is a T or NK clonal disorder characterized by the tissue invasion of marrow, spleen and liver...

O presente estudo tem como objetivo o estabelecimento de fundamentação teórica atualizada baseada em revisão bibliográfica sobre a leucemia de grandes linfócitos granulares (LGLG), doença onco-hematológica, que, devido à sua relativa raridade, é pouco conhecida e subdiagnosticada. A LGLG é caracterizada pela proliferação clonal de linfócitos T ou NK na medula óssea e/ou no sangue periférico. Dentre as manifestações clínico-laboratoriais, podem ocorrer citopenias (anemia e/ou neutropenia e/ou plaquetopenia), linfocitose (não costuma ser acentuada), linfadenomegalia, hepatoesplenomegalia, alterações imunológicas e sintomas constitucionais (emagrecimento, febre e sudorese). O curso clínico da LGLG é bastante variável, sendo que no subtipo T costuma ser indolente ou oligossintomática, enquanto no subtipo NK a evolução costuma ser desfavorável. O diagnóstico é firmado através de imunofenotipagem por citometria de fluxo e estudo de clonalidade por métodos de biologia molecular. Seu tratamento é bastante diversificado e é definido de acordo com a apresentação clínica da doença. This is a literature review about large granular lymphocyte leukemia (LGLL), a rare and misdiagnosed oncohematological disease, characterized by a clonal expansion of T-cells (T-LGLL) or NK-cells (NK-LGLL) in the bone marrow and/or peripheral blood. The clinical features of LGLL include cytopenias (anemia, neutropenia and thrombocytopenia), lymphocytosis (usually discrete), lymphadenopathy, hepatomegaly, splenomegaly, immune abnormalities and constitutional symptoms (fever, night sweats and weight loss). The diagnosis is based on the confirmation of the clonality of T-cells or NK-cells (polymerase chain reaction and Southern blot are the two methods most commonly used) and typical findings of the immunophenotypic analysis of peripheral blood lymphocytes (flow cytometry analyses for specific surface antigens). In contrast to the chronic and indolent course of T-LGLL, NK-LGLL has an acute presentation and poor clinical outcome. There are different current treatment options, depending on clinical presentation.

Tγδ large granular lymphocyte leukemia (Tγδ LGLL) is a rare lymphoproliferative disease, scantily described in literature. A deep-analysis, in an initial cohort of 9 Tγδ LGLL compared to 23 healthy controls, shows that Tγδ LGLL dominant clonotypes are mainly public and exhibit different V-(D)-J γ/δ usage between patients with symptomatic and indolent Tγδ neoplasm. Moreover, some clonotypes share the same rearranged sequence. Data obtained in an enlarged cohort (n = 36) indicate the importance of a combined evaluation of immunophenotype and STAT mutational profile for the correct management of patients with Tγδ cell expansions. In fact, we observe an association between Vδ2/Vγ9 clonality and indolent course, while Vδ2/Vγ9 negativity correlates with symptomatic disease. Moreover, the 7 patients with STAT3 mutations have neutropenia and a CD56-/Vδ2- phenotype, and the 3 cases with STAT5B mutations display an asymptomatic clinical course and CD56/Vδ2 expression. All these data indicate that biological characterization is needed for Tγδ-cell neoplasm definition.