Pathogenesis of neutropenia in large granular lymphocyte leukemia and Felty syndrome

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.

Not all LGL leukemias are created equal

Large Granular Lymphocyte (LGL) Leukemia is a rare, heterogeneous even more that once thought, chronic lymphoproliferative disorder characterized by the clonal expansion of T- or NK-LGLs that requires appropriate immunophenotypic and molecular characterization. As in many other hematological conditions, genomic features are taking research efforts one step further and are also becoming instrumental in refining discrete subsets of LGL disorders. In particular, STAT3 and STAT5B mutations may be harbored in leukemic cells and their presence has been linked to diagnosis of LGL disorders. On clinical grounds, a correlation has been established in CD8+ T-LGLL patients between STAT3 mutations and clinical features, in particular neutropenia that favors the onset of severe infections. Revisiting biological aspects, clinical features as well as current and predictable emerging treatments of these disorders, we will herein discuss why appropriate dissection of different disease variants is needed to better manage patients with LGL disorders.

Pathogenesis of Extraarticular Manifestations in Rheumatoid Arthritis-A Comprehensive Review

Rheumatoid arthritis (RA) is among the most prevalent and debilitating autoimmune inflammatory chronic diseases. Although it is primarily characterized by destructive peripheral arthritis, it is a systemic disease, and RA-related extraarticular manifestations (EAMs) can affect almost every organ, exhibit a multitude of clinical presentations, and can even be asymptomatic. Importantly, EAMs largely contribute to the quality of life and mortality of RA patients, particularly substantially increased risk of cardiovascular disease (CVD) which is the leading cause of death in RA patients. In spite of known risk factors related to EAM development, a more in-depth understanding of its pathophysiology is lacking. Improved knowledge of EAMs and their comparison to the pathogenesis of arthritis in RA could lead to a better understanding of RA inflammation overall and its initial phases. Taking into account that RA is a disorder that has many faces and that each person experiences it and responds to treatments differently, gaining a better understanding of the connections between the joint and extra-joint manifestations could help to create new treatments and improve the overall approach to the patient.

Genetic susceptibility for autoimmune diseases and white blood cell count

Some autoimmune (AI) conditions affect white blood cell (WBC) counts. Whether a genetic predisposition to AI disease associates with WBC counts in populations expected to have low numbers of AI cases is not known. We developed genetic instruments for 7 AI diseases using genome-wide association study summary statistics. Two-sample inverse variance weighted regression (IVWR) was used to determine associations between each instrument and WBC counts. Effect size represents change in transformed WBC counts per change in log odds-ratio of the disease. For AI diseases with significant associations by IVWR, polygenic risk scores (PRS) were used to test for associations with measured WBC counts in individuals of European ancestry in a community-based (ARIC, n = 8926), and a medical-center derived cohort (BioVU, n = 40,461). The IVWR analyses revealed significant associations between 3 AI diseases and WBC counts: systemic lupus erythematous (Beta = - 0.05 [95% CI, - 0.06, - 0.03]), multiple sclerosis (Beta =  - 0.06 [- 0.10, - 0.03]), and rheumatoid arthritis (Beta = 0.02 [0.01, 0.03]). PRS for these diseases showed associations with measured WBC counts in ARIC and BioVU. Effect sizes tended to be larger among females, consistent with the known higher prevalence of these diseases among this group. This study shows that genetic predisposition to systemic lupus erythematosus, rheumatoid arthritis, and multiple sclerosis was associated with WBC counts, even in populations expected to have very low numbers of disease cases.

STAT3 mutations in “gray-zone” cases of T-cell large granular lymphocytic leukemia associated with autoimmune rheumatic diseases

A persistently increased T-cell large granular lymphocyte (T-LGL) count in the blood of more than 2 × 10⁹/L for at least 6 months is necessary for a reliable diagnosis of T-LGL leukemia. In cases with LGL counts of approximately 0.5–2 × 10⁹/L, a diagnosis of T-LGL leukemia can be made if clonal rearrangement of T-cell receptor (TCR) genes is present and if the patient shows typical manifestations of T-LGL leukemia, such as cytopenia, splenomegaly, or concomitant autoimmune disease. However, in cases with LGL counts of less than 0.5 × 10⁹/L, the diagnosis of T-LGL leukemia is questionable (termed as “gray-zone” cases). Although mutations in signal transducer and activator of transcription 3 (STAT3) gene are the molecular hallmark of T-LGL leukemia, their diagnostic value in the “gray-zone” cases of T-LGL leukemia has not been evaluated – our study has been aimed to examine the prevalence of STAT3 mutations in these cases. Herein, we describe 25 patients with autoimmune rheumatic diseases, neutropenia, clonal rearrangement of TCR genes, and circulating LGL count of less than 0.5 × 10⁹/L. Splenomegaly was observed in 19 (76%) patients. Mutations in the STAT3 were detected in 56% of patients using next-generation sequencing. Importantly, in 3 patients, no involvement of the blood and bone marrow by malignant LGLs was noted, but examination of splenic tissue revealed infiltration by clonal cytotoxic T-lymphocytes within the red pulp, with greater prominence in the cords. We suggest using the term “splenic variant of T-LGL leukemia” for such cases.

[Differential diagnosis of reactive cytopenias]

Reactive cytopenias are a frequent cause for bone marrow investigations, including bone marrow trephine biopsies, especially if clinical examination and laboratory analyses (e.g., detection of substrate deficiencies) cannot provide a sufficient explanation. The evaluation of such biopsies is primarily concerned with the exclusion of diseases that displace the normal hematopoiesis (infiltrates of acute leukemias or lymphomas and metastases), the exclusion of a myelodysplastic syndrome that classically results in ineffective hematopoiesis, or the detection of specific diseases, particularly infectious or histiocytic diseases (e.g., hemophagocytic lymphohistiocytosis).In this review, we describe characteristic morphologic changes of reactive cytopenias, focus on specific infectious and noninfectious clinical pictures, and distinguish them from malignant changes, especially myelodysplastic syndrome and underlying leukemia of large granular T lymphocytes. Drug-induced changes in hematopoiesis are described in another article in this issue.

Case Report: First Report of T-Cell Large Granular Lymphocytic Leukemia With NPL-DHX9 Gene Fusion Successfully Treated With Cladribine: Clinical Experience and Literature Review

Background

T-cell large granular lymphocytic leukemia (T-LGLL) is a rare lymphoproliferative disorder that starts in T cells and is usually indolent. Long-term use of immunosuppressants, combined with agranulocytosis, is a double-edged sword, as both can lead to serious infections, especially in patients with combined hematologic malignancies and immune defects.

Case Presentation

A 30-year-old female patient was admitted to the hospital because of agranulocytosis for five years, with chest tightness, fatigue, and fever for two days. Pathology and metagenomic next-generation sequencing (mNGS) detected Aspergillus. Although she received cyclosporine and methylprednisolone, the patient showed drug intolerance and progression with invasive pulmonary fungal infections. After a bone marrow aspiration biopsy and other related examinations, she was diagnosed with T-LGLL and invasive pulmonary aspergillosis (IPA). T-cell immunophenotype was CD45+CD3dim+CD5-CD4-CD8+CD7+CD57p+CD25-CD30-, TCRγδ+, transducer and activator of transcripton-3 (STAT3) Y640F mutation and fusion gene NPL-DHX9 rearrangement were confirmed, which has never been reported in hematological diseases. After voriconazole regimen adjustment during treatment based on therapeutic drug concentration monitoring (TDM) and improvement in lung infection, the patient finally treated with purine nucleoside analogues (PNA) cladribine as a single agent at 0.14 mg/kg/d for 5 days. Complete response was achieved after four-cycles cladribine treatment (WBC 2.1*109/L, HGB 117 g/L, PLT 196*109/L, ANC 1.6*109/L, and ALC 0.2*109/L).

Conclusions

To our knowledge, this is the first case of T-LGLL with a rare γδ type and fusion gene NPL-DHX9 rearrangement. The patient was successfully treated with cladribine, suggesting that this regimen could be a promising therapeutic strategy for patients with aggressive T-LGLL.

Clinical characteristics and outcomes of 100 adult patients with pure red cell aplasia

Adult pure red cell aplasia (PRCA) is a rare syndrome characterized by a severe normocytic anemia, reticulocytopenia, and absence of erythroblasts from bone marrow. The standard treatment has not yet been established for PRCA, although cyclosporine (CsA), corticosteroids (CS) showed a response in PRCA. We retrospectively analyzed the clinical data of 60 primary and 40 secondary adult patients with acquired PRCA. The proportion of secondary PRCA is relatively high and commonly associated with large granular lymphocyte leukemia (LGLL) (28 cases, 70.0%). The remission-induced regimens included CS, CsA, or other agents, and the response rate was 66.7%, 71.4%, and 50%, respectively (P = 0.336). When treating with CsA, the response rate of LGLL-associated PRCA was lower than primary PRCA (42.1% vs 85.7%, P = 0.001). Logistic regression analysis showed that ORR was inversely related to LGLL-associated PRCA. LGLL-associated PRCA had poor therapeutic efficacy to CsA.

Persistent Large Granular Lymphocyte Clonal Expansions: “The Root of Many Evils”—And of Some Goodness

Simple Summary

Large granular lymphocyte leukemia (LGLL) is a chronic disorder of either mature T or NK lymphocytes. As clonal expansions of the immune system cells, difficulties in the distinction between a true neoplasia and a physiological reactive process have been common since its description. We review here the different conditions associated with persistent clonal LGL expansions and discuss their potential origin and whether they can modulate the clinical features.

Abstract

Large granular lymphocyte leukemia (LGLL) is a chronic disease of either mature phenotype cytotoxic CD3+ T lymphocytes or CD3- NK cells. LGLL diagnosis is hampered by the fact that reactive persistent clonal LGL expansions may fulfill the current criteria for LGLL diagnoses. In addition to the presence of characteristic clinical and hematological signs such as anemia or neutropenia, LGLL/LGL clonal expansions have been associated with an array of conditions/disorders. We review here the presence of these persistent clonal expansions in autoimmune, hematological disorders and solid neoplasms and after hematopoietic stem cell transplantation. These associations are a unique translational research framework to discern whether these persistently expanded LGL clones are causes or consequences of the concomitant clinical settings and, more importantly, when they should be targeted.

Felty's syndrome - a rare case of febrile neutropenia

Felty's syndrome (rheumatoid arthritis with neutropenia and splenomegaly) is a rare condition with poor long-term prognosis, mainly as a result of severe infection risk. An effective treatment strategy has not been developed so far and current treatment options are based upon case reports, small series and clinical experience since no randomized clinical trials are available. The authors describe the case of a 53-year-old female patient with a 14-year history of rheumatoid arthritis presenting with fever, neutropenia and splenomegaly. Broad-spectrum antibiotics and granulocyte colony-stimulating factor were administered with good clinical outcome and low dose methotrexate for disease control was successfully initiated after discharge. We would like to highlight the importance of being aware of this syndrome in the differential diagnosis of long term rheumatoid arthritis patients presenting with febrile neutropenia.

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.

Autoimmune Complications in Hematologic Neoplasms

Autoimmune cytopenias (AICy) and autoimmune diseases (AID) can complicate both lymphoid and myeloid neoplasms, and often represent a diagnostic and therapeutic challenge. While autoimmune hemolytic anemia (AIHA) and immune thrombocytopenia (ITP) are well known, other rarer AICy (autoimmune neutropenia, aplastic anemia, and pure red cell aplasia) and AID (systemic lupus erythematosus, rheumatoid arthritis, vasculitis, thyroiditis, and others) are poorly recognized. This review analyses the available literature of the last 30 years regarding the occurrence of AICy/AID in different onco-hematologic conditions. The latter include chronic lymphocytic leukemia (CLL), lymphomas, multiple myeloma, myelodysplastic syndromes (MDS), chronic myelomonocytic leukemia (CMML), myeloproliferative neoplasms, and acute leukemias. On the whole, AICy are observed in up to 10% of CLL and with higher frequencies in certain subtypes of non-Hodgkin lymphoma, whilst they occur in less than 1% of low-risk MDS and CMML. AID are described in up to 30% of myeloid and lymphoid patients, including immune-mediated hemostatic disorders (acquired hemophilia, thrombotic thrombocytopenic purpura, and anti-phospholipid syndrome) that may be severe and fatal. Additionally, AICy/AID are found in about 10% of patients receiving hematopoietic stem cell transplant or treatment with new checkpoint inhibitors. Besides the diagnostic difficulties, these AICy/AID may complicate the clinical management of already immunocompromised patients.

Analysis of a single-institution cohort of patients with Felty's syndrome and T-cell large granular lymphocytic leukemia in the setting of rheumatoid arthritis

T-cell large granular lymphocytic leukemia (T-LGLL) is a lymphoproliferative disorder characterized by a persistent increase in the number of large granular lymphocytes (LGLs), neutropenia, and splenomegaly. Clinical manifestations of T-LGLL in the setting of rheumatoid arthritis (RA) are often identical to those in which one would suspect Felty's syndrome (FS). These disorders are distinguished by the presence of T-cell clonality, which is present in T-LGLL but not in FS. Mutations in the signal transducer and activator of transcription 3 (STAT3) and 5b (STAT5b) genes can be used as molecular markers of T-LGLL, but their prevalence in FS is unknown.Eighty-one patients with RA and unexplained neutropenia or/and an increase in the number of LGLs above 2 × 10⁹/L were stratified into RA-associated T-LGLL (N = 56) or FS (N = 25) groups based on the presence or absence of T-cell clonality. STAT3 and STAT5b gene mutations were assessed in each group by means of allele-specific polymerase chain reaction assays. Clinical, immunological, laboratory data and the results of immunophenotyping of blood and bone marrow lymphocytes were also evaluated.Mutations of the STAT3 gene and an increase in the number of LGLs above 2 × 10⁹/L were detected in RA-associated T-LGLL, but not in FS (39% vs 0% and 21% vs 0%, respectively). Mutations in the STAT5b gene were not observed in either group. Expression of CD57, CD16, and CD5^-/dim on CD3⁺CD8⁺ T-lymphocytes was observed in both RA-associated T-LGLL and FS.STAT3 gene mutations or LGL counts over 2 × 10⁹/L in RA patients are indicative of T-LGLL.

Successful abatacept treatment for Felty's syndrome in a patient with rheumatoid arthritis

We report the case of a 69-year-old man with a 38-year history of rheumatoid arthritis (RA), who developed Felty's syndrome, successful treatment with abatacept (ABT). He was treated with etanercept 50 mg/w and methotrexate 8 mg/w for the past 5 years. He was suffered from febrile neutropenia 6 months ago. Etanercept and methotrexate was discontinued 3 months ago, however, neutrophil count was not changed. Abdominal ultrasound showed splenomegaly, the diagnosis of Felty's syndrome was made. Granulocyte colony-stimulating factor therapy showed no effect on neutropenia, he was treated with ABT. After ABT therapy, absolute neutrophil count was elevated 234/μL to 1840/μL.

T-Cell Large Granular Lymphocyte Leukemia in a Patient With Rheumatoid Arthritis

Large granular lymphocyte leukemia (LGL) is a clonal, lymphoproliferative disorder with an indolent disease course. T-cell LGL (T-LGL) is the most common type of LGL driven from T-cell lineage (85%). The coexistence of T-LGL with several types of autoimmune disorders, mostly rheumatoid arthritis (RA), has been reported. Felty’s syndrome (FS) is defined by splenomegaly, low neutrophil count, and destructive arthritis and is usually seen in <1% of patients with RA. About 30% to 40% of patients with FS have been reported to have an expansion of large granulated lymphocytes in the circulation. FS and T-LGL are similar in terms of clinical manifestations, response to immunosuppressive therapy, their smoldering course, and immunogenetic findings, proposing FS and T-LGL with RA might be different aspects of a single disease spectrum. In this article, we present a case with long-standing RA who had never been on DMARD (Disease Modifying Anti-Rheumatic Drugs) treatment found to have constitutional symptoms, neutropenia, and splenomegaly, and the patient was diagnosed with T-LGL.

High Incidence of Clonal CD8+ T-cell Proliferation in Non-malignant Conditions May Reduce the Significance of T-cell Clonality Assay for Differential Diagnosis in Oncohematology

Polymerase chain reaction (PCR) analysis of rearranged T-cell receptor (TCR) genes is a valuable diagnostic tool for differential diagnosis of T-cell large granular lymphocytic (T-LGL) leukemia and reactive lymphocytosis. Age-related narrowing of T-cells repertoire and expansion of immune or autoimmune clones may lead to false-positive results. The objective of this study was to evaluate the specificity and positive predictive value of PCR-based clonality assessment for a differential diagnostics of T-LGL leukemia. Rearrangements of TCRG and TCRB genes using the BIOMED-2 protocol were assessed in healthy individuals including the elderly (n = 62) and patients with rheumatic diseases (n = 14), transitory reactive CD8+ lymphocytosis (n = 17), and T-LGL leukemia (n = 42). Monoclonal TCRG/TCRB rearrangements in blood were identified in 11.3%/4.8% (7/3 of 62) of healthy individuals; 21.4%/14.3% (3/2 of 14) of patients with rheumatic diseases, and 17.6%/11.8% (3/2 of 17) of patients with reactive lymphocytosis. Immunomagnetic selection of lymphocytes in healthy individuals (31 of 33) revealed that clonal T-cells belong to CD8+ and CD57+ population. No clonal Vβ-Jβ TCRB rearrangements were found in the control group, only Dβ-Jβ TCRB and TCRG. Given the high detectability (96.7%) of Vβ-Jβ TCRB monoclonal rearrangements in patients with αβ-T-LGL leukemia, this marker had the greatest specificity and positive predictive value (100%; 99.2%). The presence of clonal CD8+CD57+ cells in blood is common for healthy individuals and patients with reactive conditions and may not associate with any malignancy. Different specificity of TCRG/ Dβ-Jβ TRB/ Vβ-Jβ TCRB PCR reactions should be taken into account for T-cell clonality data interpretation.

[Hepatocellular failure revealing T-cell large granular lymphocyte leukemia: Morocco case study and literature review]

La leucémie à grands lymphocytes granuleux type T (T-LGL) fait partie des hémopathies lymphoïdes à cellules T/NK (natural killer) matures dans la dernière classification de l'organisation mondiale de santé (OMS) 2016. La T-LGL est caractérisée par un phénotype T CD3+ et un réarrangement du gène TCR (récepteur de lymphocyte T). C'est une entité rare qui s'observe essentiellement en occident. Nous rapportons le cas d'un patient de 60 ans, d'origine marocaine, qui présente depuis 1 mois un ictère généralisé avec des pétéchies diffuses et altération de l'état général, l'examen clinique initial objective une ascite de moyenne abondance et hépatosplénomégalie, l'examen paraclinique montre des signes biologiques d'insuffisance hépatocellulaire avec une neutropénie et thrombopénie. Le diagnostic de la T-LGL est retenu par l'étude cytologique et immunophénotyique du sang médullaire ainsi que la détection de réarrangement de TCR à la biologie moléculaire. Le patient est mis sous cyclophosphamide avec traitement symptomatique. L'évolution est fatale avec décès du patient 3 mois après le diagnostic par un choc septique sur un état de cachexie. La T-LGL est d'évolution très souvent indolente et son tableau clinique initial au diagnostic est généralement modéré et d'installation progressive et ce n'est pas le cas chez notre patient. Un syndrome d'insuffisance hépatocellulaire est exceptionnellement inaugural d'une leucémie à grands lymphocytes granuleux type T.

Latest Advances in the Diagnosis and Treatment of Large Granular Lymphocytic Leukemia

Large granular lymphocyte (LGL) leukemia has been recognized in the World Health Organization classifications among mature T cell and natural killer cell neoplasms and is divided into three categories. Chronic T cell leukemia and natural killer cell lymphocytosis can be considered as a similar spectrum of an indolent disease characterized by cytopenias and autoimmune conditions. The last category, aggressive natural killer cell LGL leukemia is very rare, related to Epstein-Barr virus, and seen mainly in young Asian people. Clonal LGL expansion arises from chronic antigenic stimulation sustained by interleukin-15 and platelet-derived growth factor cytokine signal. Those leukemic cells are resistant to apoptosis, mainly because of constitutive activation of survival pathways including Jak/Stat, MapK, Pi3k-Akt, RasRaf-1, MEK1/ERK, sphingolipid, and NFκB. Stat3 constitutive activation is the hallmark of this lymphoproliferative disorder. Socs3 is downregulated, but no mutation could be found to explain this status. However, several somatic mutations, including Stat3, Stat5b, and tumor necrosis factor alpha-induced protein 3, have been demonstrated recently in LGL leukemia; they are identified in half of patients and cannot explain by themselves LGL leukemogenesis. Recurrent infections as a result of chronic neutropenia, anemia, and autoimmune disorders are the main complications related to LGL leukemia. Despite an indolent presentation, 10% of patients die, mainly because of infectious complications. Current treatments are based on immunosuppressive therapies. A better mechanistic understanding of LGL leukemia will allow future consideration of a personalized therapeutic approach perhaps based on Jak/Stat inhibitors, which may offer better results than current immunosuppressive therapy.

Large granular leukemia with concurrent central nervous system and articular infiltration in a cat

A 2-year-old female domestic shorthair cat was referred with a 2 month history of lethargy, weight loss, recurrent hyperthermia and polyarthropathy despite prednisolone. Upon physical examination, the cat showed apathy, hyperthermia, multiple appendicular joint pain and swelling. The CBC showed severe macrocytic normochromic non-regenerative anemia and thrombocytopenia. A population of immature large granular lymphocytes (LGL) was noted on blood smear. Abdominal ultrasonography revealed enlarged mesenteric lymph nodes (LNs), hyper echoic liver and splenomegaly. Cytology of fine needle aspirate of synovial fluid, spleen, liver, enlarged abdominal LNs and bone marrow supported a diagnosis of LGL leukemia with concurrent articular infiltration. A COP-based protocol was initiated with L-asparaginase (400 UI/kg intramuscularly) and prednisolone (1 mg/kg/day orally). However, the cat presented 1 week later with obtundation and paresis, indicating the involvement of the central nervous system (CNS). LGL were also observed on cerebrospinal fluid analysis. Histologic examination noted LGL in the spleen, liver and LNs. Immunohistochemistry (IHC) yielded negative results for both B- and T-cells thus suggesting NK-cells. The diagnosis was LGL leukemia with concurrent articular and CNS involvement. Articular infiltration with LGL is rarely reported in small animals, whereas CNS involvement was previously only suspected in a cat at necropsy.

Successful treatment of cerebral aspergillosis: case report of a patient with T-cell large granular lymphocytic leukemia (T-LGL)

Background

Invasive aspergillosis involving patients with neutropenia or severe immunosuppression, such as patients with hematologic malignancies is associated with high mortality. Patients with T-cell large granular lymphocytic leukemia (T-LGL) on the other hand are considered to be less vulnerable for severe opportunistic fungal infection as their course of disease is chronic and marked by less violent cytopenia then in e.g. Aplastic Anemia. Only neutropenia is regarded as independent risk factor for severe opportunistic infection in T-LGL patients.

Case presentation

We report a case of a 53 year old patient with T-LGL, Immune-Thrombocytopenia (ITP) and combined antibody deficiency, who presented with fever and reduced general condition. The patient revealed a complicated infection involving the lungs and later the brain, with the presentation of vomiting and seizures. Broad microbiological testing of blood-, lung- and cerebrospinal fluid samples was inconclusive. In the absence of mycological proof, Aspergillus infection was confirmed by pathological examination of a brain specimen and finally successfully treated with liposomal amphotericin B and voriconazole, adopting a long-term treatment scheme.

Conclusions

Beyond typical problems in the clinical practice involving fungal infections and hematologic malignancies, this case of invasive aspergillosis in a patient with T-LGL illustrates caveats in diagnosis, therapy and follow-up. Our data support careful ambulatory monitoring for patients with T-LGL, even in the absence of neutropenia. Especially those patients with combined hematologic malignancies and immune defects are at risk. Long-term treatment adhesion for 12 months with sufficient drug levels was necessary for sustained clearance from infection.

Chronic neutropenia in LGL leukemia and rheumatoid arthritis

This section reviews the diagnostic criteria and pathogenesis of large granular lymphocyte (LGL) leukemia. There is a particular focus on the overlap of LGL leukemia and rheumatoid arthritis (Felty's syndrome). Current understanding of the mechanisms of neutropenia in these disorders is discussed. Finally, treatment indications and therapeutic recommendations are outlined.

Somatic STAT3 mutations in Felty syndrome: an implication for a common pathogenesis with large granular lymphocyte leukemia

Felty syndrome is a rare disease defined by neutropenia, splenomegaly, and rheumatoid arthritis. Sometimes the differential diagnosis between Felty syndrome and large granular lymphocyte leukemia is problematic. Recently, somatic STAT3 and STAT5B mutations were discovered in 30–40% of patients with large granular lymphocyte leukemia. Herein, we aimed to study whether these mutations can also be detected in Felty syndrome, which would imply the existence of a common pathogenic mechanism between these two disease entities. We collected samples and clinical information from 14 Felty syndrome patients who were monitored at the rheumatology outpatient clinic for Felty syndrome. Somatic STAT3 mutations were discovered in 43% (6/14) of Felty syndrome patients with deep amplicon sequencing targeting all STAT3 exons. Mutations were located in the SH2 domain of STAT3, which is a known mutational hotspot. No STAT5B mutations were found. In blood smears, overrepresentation of large granular lymphocytes was observed, and in the majority of cases the CD8⁺ T-cell receptor repertoire was skewed when analyzed by flow cytometry. In bone marrow biopsies, an increased amount of phospho-STAT3 positive cells was discovered. Plasma cytokine profiling showed that ten of the 92 assayed cytokines were elevated both in Felty syndrome and large granular lymphocyte leukemia, and three of these cytokines were also increased in patients with uncomplicated rheumatoid arthritis. In conclusion, somatic STAT3 mutations and STAT3 activation are as frequent in Felty syndrome as they are in large granular lymphocyte leukemia. Considering that the symptoms and treatment modalities are also similar, a unified reclassification of these two syndromes is warranted.

Immune and myodegenerative pathomechanisms in inclusion body myositis

Inclusion Body Myositis (IBM) is a relatively common acquired inflammatory myopathy in patients above 50 years of age. Pathological hallmarks of IBM are intramyofiber protein inclusions and endomysial inflammation, indicating that both myodegenerative and inflammatory mechanisms contribute to its pathogenesis. Impaired protein degradation by the autophagic machinery, which regulates innate and adaptive immune responses, in skeletal muscle fibers has recently been identified as a potential key pathomechanism in IBM. Immunotherapies, which are successfully used for treating other inflammatory myopathies lack efficacy in IBM and so far no effective treatment is available. Thus, a better understanding of the mechanistic pathways underlying progressive muscle weakness and atrophy in IBM is crucial in identifying novel promising targets for therapeutic intervention. Here, we discuss recent insights into the pathomechanistic network of mutually dependent inflammatory and degenerative events during IBM.

LGL leukemia: from pathogenesis to treatment

Large granular lymphocyte (LGL) leukemia has been recognized by the World Health Organization classifications amongst mature T-cell and natural killer (NK) cell neoplasms. There are 3 categories: chronic T-cell leukemia and NK-cell lymphocytosis, which are similarly indolent diseases characterized by cytopenias and autoimmune conditions as opposed to aggressive NK-cell LGL leukemia. Clonal LGL expansion arise from chronic antigenic stimulation, which promotes dysregulation of apoptosis, mainly due to constitutive activation of survival pathways including Jak/Stat, MapK, phosphatidylinositol 3-kinase-Akt, Ras-Raf-1, MEK1/extracellular signal-regulated kinase, sphingolipid, and nuclear factor-κB. Socs3 downregulation may also contribute to Stat3 activation. Interleukin 15 plays a key role in activation of leukemic LGL. Several somatic mutations including Stat3, Stat5b, and tumor necrosis factor alpha-induced protein 3 have been demonstrated recently in LGL leukemia. Because these mutations are present in less than half of the patients, they cannot completely explain LGL leukemogenesis. A better mechanistic understanding of leukemic LGL survival will allow future consideration of a more targeted therapeutic approach than the current practice of immunosuppressive therapy.

Atypical aleukemic presentation of large granular lymphocytic leukemia: a case report

Large granular lymphocytic leukemia (LGLL) is a rare lymphoproliferative disorder of transformed natural killer or T-cells attributed to chronic exposure to the proinflammatory cytokine IL-15. Diagnosis of the majority of T-cell LGLL is established by documenting clonal large granular lymphocytes (LGLs) in peripheral blood, by morphology and immunophenotype. The proteasome inhibitor bortezomib is known to target molecular pathways downstream of the IL-15 receptor signaling and has been proposed as a therapy in these patients. We report an uncommon presentation of LGLL with chronic neutropenia lacking typical blood LGLs, which failed to respond to bortezomib but obtained a very good partial remission with a classical methotrexate regimen.

Felty's Syndrome, Insights and Updates

Felty’s syndrome (FS) is characterized by the triad of seropositive rheumatoid arthritis (RA) with destructive joint involvement, splenomegaly and neutropenia. Current data shows that 1-3 % of RA patients are complicated with FS with an estimated prevalence of 10 per 100,000 populations. The complete triad is not an absolute requirement, but persistent neutropenia with an absolute neutrophil count (ANC) generally less than 1500/mm3 is necessary for establishing the diagnosis. Felty’s syndrome may be asymptomatic but serious local or systemic infections may be the first clue to the diagnosis. FS is easily overlooked by parallel diagnoses of Sjӧgren syndrome or systemic lupus erythematosus or lymphohematopoietic malignancies. The role of genetic (HLA DR4) is more prominent in FS in comparison to classic rheumatoid arthritis. There is large body of evidence that in FS patients, both cellular and humoral immune systems participate in neutrophil activation, and apoptosis and its adherence to endothelial cells in the spleen. It has been demonstrated that proinflammatory cytokines may have inhibitory effects on bone marrow granulopoiesis. Binding of IgGs to neutrophil extracellular chromatin traps (NET) leading to neutrophil death plays a crucial role in its pathophysiology. In turn, "Netting" neutrophils may activate auto-reactive B cells leading to further antibody and immune complex formation. In this review we discuss on basic pathophysiology, epidemiology, genetics, clinical, laboratory and treatment updates of Felty’s syndrome.

Advances in diagnosis and treatment of large granular lymphocyte syndrome

PURPOSE OF REVIEW

Large granular lymphocyte (LGL) syndrome comprises a clonal spectrum of T-cell and natural killer (NK)-cell LGL lymphoproliferative disorders associated with neutropenia. This review presents advances in diagnosis and therapy of LGL syndrome.

RECENT FINDINGS

Due to the lack of a single unique genetic or phenotypic feature and clinicopathological overlap between reactive and neoplastic entities, accurate LGL syndrome diagnosis should be based on the combination of morphologic, immunophenotypic, and molecular studies as well as clinical features. For diagnosis and monitoring of LGL proliferations, it is essential to perform flow cytometric blood and/or bone marrow analysis using a panel of monoclonal antibodies to conventional and novel T-cell and NK-cell antigens such as NK-cell receptors and T-cell receptor β-chain variable region families together with TCR gene rearrangement studies. Treatment of symptomatic cytopenias in patients with indolent LGL leukemia is still based on immunosuppressive therapy. Treatment with purine analogs and alemtuzumab may be considered as an alternative option.

SUMMARY

Progress in understanding the pathogenetic mechanisms of these entities, especially resistance of clonal LGLs to apoptosis, due to constitutive activation of survival signaling pathways, has its impact on identification of potential molecular therapeutic targets.

The analysis of clonal diversity and therapy responses using STAT3 mutations as a molecular marker in large granular lymphocytic leukemia

T-cell large granular lymphocytic leukemia and chronic lymphoproliferative disorder of natural killer cells are intriguing entities between benign and malignant lymphoproliferation. The molecular pathogenesis has partly been uncovered by the recent discovery of somatic activating STAT3 and STAT5b mutations. Here we show that 43% (75/174) of patients with T-cell large granular lymphocytic leukemia and 18% (7/39) with chronic lymphoproliferative disorder of natural killer cells harbor STAT3 mutations when analyzed by quantitative deep amplicon sequencing. Surprisingly, 17% of the STAT3-mutated patients carried multiple STAT3 mutations, which were located in different lymphocyte clones. The size of the mutated clone correlated well with the degree of clonal expansion of the T-cell repertoire analyzed by T-cell receptor beta chain deep sequencing. The analysis of sequential samples suggested that current immunosuppressive therapy is not able to reduce the level of the mutated clone in most cases, thus warranting the search for novel targeted therapies. Our findings imply that the clonal landscape of large granular lymphocytic leukemia is more complex than considered before, and a substantial number of patients have multiple lymphocyte subclones harboring different STAT3 mutations, thus mimicking the situation in acute leukemia.

Immune-mediated pore-forming pathways induce cellular hypercitrullination and generate citrullinated autoantigens in rheumatoid arthritis

Autoantibodies to citrullinated protein antigens are specific markers of rheumatoid arthritis (RA). Although protein citrullination can be activated by numerous stimuli in cells, it remains unclear which of these produce the prominent citrullinated autoantigens targeted in RA. In these studies, we show that RA synovial fluid cells have an unusual pattern of citrullination with marked citrullination of proteins across the broad range of molecular weights, which we term cellular hypercitrullination. Although histone citrullination is a common event during neutrophil activation and death induced by different pathways including apoptosis, NETosis, and necroptosis/autophagy, hypercitrullination is not induced by these stimuli. However, marked hypercitrullination is induced by two immune-mediated membranolytic pathways, mediated by perforin and the membrane attack complex (MAC), which are active in the RA joint and of importance in RA pathogenesis. We further demonstrate that perforin and MAC activity on neutrophils generate the profile of citrullinated autoantigens characteristic of RA. These data suggest that activation of peptidylarginine deiminases during complement and perforin activity may be at the core of citrullinated autoantigen production in RA. These pathways may be amenable to monitoring and therapeutic modulation.

Autoimmune neutropenia

Autoimmune neutropenia (AIN) is a rare entity caused by antibodies directed against neutrophil-specific antigens. It includes primary and secondary autoimmune neutropenia. Acute autoimmune neutropenia can be related to drug-induced mechanism or viral infections. Chronic autoimmune neutropenias occur in the context of autoimmune diseases, hematological malignancies, such as large granular lymphocyte leukemia, primary immune deficiency syndromes or solid tumors. The therapeutic management depends on the etiology. Granulocyte growth factor is the main therapeutic option, raising the question of their long-term utilization safety. Corticosteroids or immunosuppressive therapy are indicated in infection-related AIN or in case of symptomatic autoimmune disease or LGL leukemia.

The pathogenesis and treatment of large granular lymphocyte leukemia

Large granular lymphocyte (LGL) leukemia is a spectrum of rare lymphoproliferative diseases of T lymphocytes and natural killer cells. These diseases frequently present with splenomegaly, neutropenia, and autoimmune diseases like rheumatoid arthritis. LGL leukemia is more commonly of a chronic, indolent nature; however, rarely, they have an aggressive course. LGL leukemia is thought to arise from chronic antigen stimulation, which drives long-term cell survival through the activation of survival signaling pathways and suppression of pro-apoptotic signals. These include Jak-Stat, Mapk, Pi3k-Akt, sphingolipid, and IL-15/Pdgf signaling. Treatment traditionally includes immunosuppression with low dose methotrexate, cyclophosphamide, and other immunosuppressive agents; however, prospective and retrospective studies reveal very limited success. New studies surrounding Jak-Stat signaling suggest this may reveal new avenues for LGL leukemia therapeutics.

Diagnostic criteria for autoimmune neutropenia

Autoimmune neutropenia denotes that the number of circulating polymorphonuclear neutrophils is below 1.5×10(9)/L. This encompasses a wide range of disorders from primary conditions to complications of systemic autoimmune diseases or hematological neoplasms. Antineutrophil autoantibodies are particularly difficult to detect, and their amount does not correlate with the degree of neutropenia. Granulocyte colony-stimulating factor is the first-line therapy, but should be restricted to patients with total absence of neutrophils and/or severe infections.

Autoimmune cytopenias in chronic lymphocytic leukemia, facts and myths

CLL has been defined as presence of more than 5000 small mature appearing monoclonal B lymphocytes with a specific immunophenotype in peripheral blood. It is a well-known fact that CLL is associated with autoimmune cytopenias. CLL cells are CD5(+) B lymphocytes, and usually are not the "guilty" cells which produce autoantibodies. T cell defect is another characteristic of CLL and the total number of T cells is increased, and there is inversion of the CD4/CD8 ratio. Autoimmune hemolytic anemia (AIHA) is the most common autoimmune complication of CLL and has been reported in 10-25% of CLL patients. However, the stage-adjusted estimated rate of AIHA in CLL is about 5%. Conversely, CLL is three times more common in patients who present with AIHA. Direct agglutinin test (DAT) is positive in 7-14% of CLL patients but AIHA may also occur in DAT negative patients. Autoimmune thrombocytopenia (AIT) is the second most common complication of CLL and has been reported in 2-3% of patients. DAT is positive in AIT but presence of antiplatelet antibodies is neither diagnostic nor reliable. Autoimmune neutropenia (AIN) and pure red cell aplasia (PRCA) are very rare complications of CLL and like other autoimmune complications of CLL may occur at any clinical stage. It is believed that most case reports of AIN and PRCA in CLL actually belong to large granular lymphocytic leukemia (LGL). Non-hematologic autoimmune complications of CLL including cold agglutinin disease (CAD), paraneoplastic pemphigus (PNP), acquired angioedema, and anti-myelin associated globulin are rare. Before starting any treatment, clinicians should distinguish between autoimmune cytopenias and massive bone marrow infiltration since autoimmune complications of CLL are not necessarily equal to advanced disease with poor prognosis. According to IWCLL guideline, steroids are the mainstay of treatment of simple autoimmunity. Intravenous immunoglobulin (IVIg), cyclosporine, and rituximab are used in complex, steroid refractory cases. Monotherapy with purine analogues and alkylating agents should be avoided as they may increase CLL associated autoimmune complications.

STAT3 mutations are frequent in T-cell large granular lymphocytic leukemia with pure red cell aplasia

T-cell large granular lymphocytic leukemia (T-LGLL) is a rare lymphoproliferative disorder and can cooccur in the context of pure red cell aplasia (PRCA). The aim of the current study was to analyze the signal transducer and activator of transcription 3 (STAT3) mutation status and its clinical significance in T-LGLL. We found STAT3 mutations in 21.4% of patients with T-LGLL. High β2-MG (β2-microglobulin) levels (P = 0.005), neutropenia (P = 0.018) and PRCA (P = 0.001) all displayed a significant association with STAT3 mutations. In univariate analysis, treatment-free survival (TFS) was affected by STAT3 mutation status (P = 0.008) and β2-MG (P = 0.006). Our results demonstrate the remarkable correlation of STAT3 mutation with PRCA, neutropenia and β2-MG.

Discovery of somatic STAT5b mutations in large granular lymphocytic leukemia

Large granular lymphocytic (LGL) leukemia is characterized by clonal expansion of cytotoxic T cells or natural killer cells. Recently, somatic mutations in the signal transducer and activator of transcription 3 (STAT3) gene were discovered in 28% to 40% of LGL leukemia patients. By exome and transcriptome sequencing of 2 STAT3 mutation-negative LGL leukemia patients, we identified a recurrent, somatic missense mutation (Y665F) in the Src-like homology 2 domain of the STAT5b gene. Targeted amplicon sequencing of 211 LGL leukemia patients revealed 2 additional patients with STAT5b mutations (N642H), resulting in a total frequency of 2% (4 of 211) of STAT5b mutations across all patients. The Y665F and N642H mutant constructs increased the transcriptional activity of STAT5 and tyrosine (Y694) phosphorylation, which was also observed in patient samples. The clinical course of the disease in patients with the N642H mutation was aggressive and fatal, clearly different from typical LGL leukemia with a relatively favorable outcome. This is the first time somatic STAT5 mutations are discovered in human cancer and further emphasizes the role of STAT family genes in the pathogenesis of LGL leukemia.

Two Suspected Cases of Immunoglobulin-Mediated Interference Causing Falsely Low Vancomycin Concentrations with the Beckman PETINIA Method

OBJECTIVE

To describe 2 recent cases of suspected immunoglobulin-mediated interference with the Beckman Coulter particle–enhanced turbidimetric inhibition immunoassay (PETINIA) used to measure vancomycin serum or plasma concentrations and to review the existing literature.

CASE SUMMARY

A 64-year-old woman with a history of multiple immune-related comorbidities received vancomycin for treatment of a prosthetic joint infection growing coagulase-negative Staphylococcus spp. A 33-year-old man with a history of Felty syndrome received vancomycin for the treatment of methicillin-resistant Staphylococcus aureus pneumonia. Both patients had multiple vancomycin trough concentrations determined using the Beckman Coulter PETINIA method and had measured concentrations reported as less than 4 mg/L despite appropriate vancomycin dosing for their size, age, and organ function. The patients' serum was then tested by alternative methods, which reported vancomycin concentrations consistent with those expected with the patients' dosing regimens.

DISCUSSION

Immunoglobulins are well known for interfering with chemistry assays. It is suspected that high levels of immunoglobulins in these 2 patients interfered with the accurate measurement of serum vancomycin concentrations. An objective causality assessment supported the interactions as being definite and probable, respectively. Two other cases of suspected immunoglobulin interference with vancomycin measurement have been reported in the literature when vancomycin concentrations were initially measured using the Beckman Coulter PETINIA method. In vitro studies support the hypothesis that immunoglobulin interference with vancomycin measurement by this method occurs and is a graded phenome non.

CONCLUSIONS

These cases suggest a high likelihood of immunoglobulin-mediated interference with the Beckman Coulter PETINIA method, which results in the reporting of falsely low vancomycin serum concentrations. When vancomycin concentrations do not correlate with what would be expected clinically, clinicians should have a high index of suspicion for potential assay interference.

The effect of paraproteins and rheumatoid factor on four commercial immunoassays for vancomycin: implications for laboratorians and other health care professionals

BACKGROUND

Paraproteins, immunoglobulins (Igs), which are elevated in various autoimmune disorders, are known to interfere with various laboratory immunoassays, including vancomycin (VANC). Rheumatoid factor (RF), a known immunoassay interferant, may cause falsely elevated results.

OBJECTIVES

The aims of this study were to (1) evaluate the effect of 3 paraproteins (IgA, IgG, and IgM) on 4 commercial VANC immunoassays [fluorescence polarization immunoassay; enzyme multiplied immunoassay; 2 particle-enhanced turbidimetric inhibition immunoassays]; (2) determine the concentration at which the effect is obtained, and (3) examine the influence of RF on the VANC methods.

METHOD

Serum and plasma pools from patients prescribed VANC and a spiked VANC pool (20 mg/L) were each mixed 1:1 with individual patient specimens containing IgA (6-63 g/L), IgG (6-54 g/L), IgM (3-30 g/L) (n = 4 for each Ig), and a patient RF pool (196 IU/L). The mixtures (n = 39) were split and distributed for VANC analysis.

RESULTS

IgA and IgG in serum and plasma did not affect any of the VANC immunoassays. RF added to plasma specimens did not interfere, but in serum, elevated VAN results were observed. IgM did not affect the fluorescence polarization immunoassay and enzyme multiplied immunoassay methods but did attenuate VANC concentrations by both particle-enhanced turbidimetric inhibition immunoassays (Siemens, Beckman Coulter), with a more pronounced effect on the latter, producing concentrations >20% lower than expected in the patient serum and spiked plasma pools. The effect was progressively negative at effective IgM concentrations of 10 and 15 mg/L.

CONCLUSIONS

This phenomenon is a major analytical and clinical issue that must be communicated to health care professionals caring for patients receiving VANC, so optimal therapy is achieved.

Somatic STAT3 mutations in large granular lymphocytic leukemia

BACKGROUND

T-cell large granular lymphocytic leukemia is a rare lymphoproliferative disorder characterized by the expansion of clonal CD3+CD8+ cytotoxic T lymphocytes (CTLs) and often associated with autoimmune disorders and immune-mediated cytopenias.

METHODS

We used next-generation exome sequencing to identify somatic mutations in CTLs from an index patient with large granular lymphocytic leukemia. Targeted resequencing was performed in a well-characterized cohort of 76 patients with this disorder, characterized by clonal T-cell-receptor rearrangements and increased numbers of large granular lymphocytes.

RESULTS

Mutations in the signal transducer and activator of transcription 3 gene (STAT3) were found in 31 of 77 patients (40%) with large granular lymphocytic leukemia. Among these 31 patients, recurrent mutational hot spots included Y640F in 13 (17%), D661V in 7 (9%), D661Y in 7 (9%), and N647I in 3 (4%). All mutations were located in exon 21, encoding the Src homology 2 (SH2) domain, which mediates the dimerization and activation of STAT protein. The amino acid changes resulted in a more hydrophobic protein surface and were associated with phosphorylation of STAT3 and its localization in the nucleus. In vitro functional studies showed that the Y640F and D661V mutations increased the transcriptional activity of STAT3. In the affected patients, downstream target genes of the STAT3 pathway (IFNGR2, BCL2L1, and JAK2) were up-regulated. Patients with STAT3 mutations presented more often with neutropenia and rheumatoid arthritis than did patients without these mutations.

CONCLUSIONS

The SH2 dimerization and activation domain of STAT3 is frequently mutated in patients with large granular lymphocytic leukemia; these findings suggest that aberrant STAT3 signaling underlies the pathogenesis of this disease. (Funded by the Academy of Finland and others.).

Pathophysiologic mechanisms and management of neutropenia associated with large granular lymphocytic leukemia

Large granular lymphocyte (LGL) syndrome includes a spectrum of clonal T cell and natural killer cell chronic lymphoproliferative disorders. These conditions are thought to arise from chronic antigenic stimulation, while the long-term survival of the abnormal LGLs appears to be sustained by resistance to apoptosis and/or impaired survival signaling. T-cell LGL (T-LGL) leukemia is the most common LGL disorder in the Western world. Despite its indolent course, the disease is often associated with neutropenia, the pathogenesis of which is multifactorial, comprising both humoral and cytotoxic mechanisms. This article addresses the pathogenesis of T-LGL leukemia and natural killer cell chronic lymphoproliferative disorder, as well as that of T-LGL leukemia-associated neutropenia. Furthermore, as symptomatic neutropenia represents an indication for initiating treatment, available therapeutic options are also discussed.