Evidence of membranolytic targeting and intracellular citrullination in neutrophils isolated from patients with rheumatoid arthritis.

Anti-citrullinated protein autoantibodies (ACPA) are diagnostic for rheumatoid arthritis (RA). The antigens recognized by these autoantibodies are produced by protein arginine deiminases (PADs), particularly PAD4. However, it remains unknown why and how PAD4 causes this aberrant citrullination in RA. Here, we report that poly-perforin pores are present on freshly isolated neutrophils from RA patients, but not on healthy donor neutrophils. Neutrophils with perforin pores also contained intracellular citrullinated proteins in the region adjacent to the pores. This response was replicated in vitro by treating neutrophils with purified perforin, which generated intense dots of anti-perforin immunofluorescence, calcium influx, and intracellular citrullination. Extensive neutrophil killing in Felty's syndrome, an aggressive form of RA, correlated with particularly high ACPA, and PAD4 autoantibodies. In contrast, other forms of death, including NETosis, apoptosis, and pyroptosis, produced minimal citrullination. We conclude that neutrophil targeting by perforin leading to intracellular citrullination takes place in patients with RA.

The spectrum of somatic mutations in large granular lymphocyte leukemia, rheumatoid arthritis, and Felty's syndrome.

T cell large granular lymphocyte leukemia (T-LGLL) is an interesting case at the intersection of autoimmunity and cancer. In T-LGLL, T cells with somatic pathogenic mutations (mainly in STAT3) are linked to rheumatoid arthritis (RA) and neutropenia. A rare subtype of RA, Felty's syndrome, exhibits overlapping clinical features and comparable frequencies of activating STAT3 mutations in T cells as T-LGLL, which hints at a potential T-LGLL-Felty's syndrome-RA axis. Somatic mutations could shed light on the unexplained pathologies of these disorders. However, the causality of somatic mutations-do somatic mutations in immune cells cause inflammation, or does prolonged inflammation predispose to mutagenesis-remains unanswered. This review will focus on the recent advances in understanding somatic mutations in T-LGLL and related autoimmune conditions as a master regulatory network that sustains lymphoproliferation and inflammation.

Hematological Manifestations among Patients with Rheumatic Diseases.

BACKGROUND: Rheumatic diseases have many hematological manifestations. Blood dyscrasias and other hematological abnormalities are sometimes the first sign of rheumatic disease. In addition, novel antirheumatic biological agents may cause cytopenias. SUMMARY: The aim of this review was to discuss cytopenias caused by systemic lupus erythematosus and antirheumatic drugs, Felty's syndrome in rheumatoid arthritis, and autoimmune hemolytic anemia, thrombosis, and thrombotic microangiopathies related to rheumatological conditions such as catastrophic antiphospholipid syndrome and scleroderma renal crisis. Key Message: The differential diagnosis of various hematological disorders should include rheumatic autoimmune diseases among other causes of blood cell and hemostasis abnormalities. It is crucial that hematologists be aware of these presentations so that they are diagnosed and treated in a timely manner.

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.

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.

Primary cardiac B cell lymphoma: Manifestation of Felty's syndrome or TNFα antagonist.

Primary cardiac B cell lymphoma is rare. To date, fewer than 90 cases have been described in the literature. We report a 67-year-old woman with a 30-year history of rheumatoid arthritis, who had received treatment with leflunomide for 10 years and infliximab for 2 years. Secondary Felty's syndrome appeared. She was admitted to the hospital for abdominal pain. Investigations disclosed a 5cm cardiac mass in the right atrium. Histopathologic examination of tissue specimens obtained at surgical myocardial biopsy demonstrated primary cardiac B cell lymphoma. The other iatrogenic lymphoproliferative disorders are reviewed. This lesion might be a manifestation of long term TNFα antagonists treatment.

Acquired inhibitors to factor VIII and fibrinogen in the setting of T-cell large granular lymphocyte leukemia: a case report and review of the literature.

Large granular lymphocyte (LGL) leukemia is an indolent lymphoproliferative malignancy which dysregulates humoral immunity and underlies the myriad autoimmune phenomena. We describe a 62-year-old woman with Felty's syndrome who developed a severe bleeding diathesis. Laboratory evaluation demonstrated acquired inhibitors to both factor VIII (FVIII) and fibrinogen, likely secondary to T-cell LGL leukemia. After a complicated course, the patient's inhibitors were extinguished with rituximab and high-dose corticosteroids. Bleeding was controlled with alternating FEIBA (factor eight inhibitor bypassing activity) and recombinant activated FVII. This report reviews the literature comparing the efficacy of various treatment modalities for both disorders. To our knowledge, this is the first reported case of a patient with LGL leukemia acquiring an inhibitor to FVIII or fibrinogen.

[Large granular lymphocyte leukemia: clinical and pathogenic aspects]. / Les leucémies à grands lymphocytes granuleux : de la clinique à la physiopathologie.

Large granular lymphocyte leukemia (LGL) is a hematologic disorder characterized by a monoclonal expansion of large lymphocytes containing azurophilic granules with a T CD3(+)CD57(+) or Natural Killer (NK) CD3(-)CD56(+) phenotype. The World Health Organization (WHO) classification identifies three entities: the T LGL, the chronic lymphoproliferative disorder of NK-cells, and the aggressive NK-cell leukemia. T LGL and chronic lymphoproliferative disorder of NK-cells are indolent diseases frequently associated with cytopenias and a wide spectrum of auto-immune manifestations. Neutropenia can lead to recurrent bacterial infections, which represent an indication of initiating a treatment in most of the cases. Immunosuppressive therapies are usually used in this context. In contrast, aggressive NK-cell leukemia follows a fulminant course with a poor prognosis because patients are refractory to most of the treatments. There is now a considerable interest in the pathophysiology of the disease with the perspective of new therapeutic options.

Autoimmune manifestations in large granular lymphocyte leukemia.

Large granular lymphocyte (LGL) leukemia features a group of indolent lymphoproliferative diseases that display a strong association with various autoimmune conditions. Notwithstanding, these autoimmune conditions have not been comprehensively characterized or systematized to date. As a result, their clinical implications remain largely unknown. The authors offer a comprehensive review of the existing literature on various autoimmune conditions documented in the course of T-cell LGL (T-LGL) leukemia. Though some of them are thought be secondary to the LGL leukemia, others could be primary and might even play a role in its pathogenesis. A considerable clinico-laboratory overlap between T-LGL leukemia associated with rheumatoid arthritis and Felty's syndrome suggests that they are just different eponyms for the same clinical entity.

Temporal bone histopathology and immunoglobulin deposition in Sjogren's syndrome.

HYPOTHESIS: The histopathology of Sjogren's syndrome (SS) in the human inner ear correlates with mouse models of autoimmune inner ear disease. BACKGROUND: SS is an autoimmune disease in which 25% of patients have sensorineural hearing loss (SNHL). The inner ear histology in a SS mouse model has shown degeneration of the stria vascularis (SV) and immunoglobulin G deposition on the basement membrane of SV blood vessels. Correlation with human temporal bone histopathology has not been addressed. METHODS: The histopathology and immunohistochemistry of the inner ear in 4 patients with SS is described and compared with SS mouse models. RESULTS: The histopathology of the inner ear in 3 patients with SS and SNHL showed severe loss of the intermediate cells of the SV and immunoglobulin G deposition on the basement membrane of SV blood vessels. These results parallel those of known SS mouse models. Additionally, there was shrinkage of the spiral ganglia neurons in 2 patients, whereas vestibular ganglia neurons were preserved. The fourth patient with SS and normal hearing showed only mild SV atrophy. CONCLUSION: This is the first study describing the pathologic changes in the inner ear of 4 patients with SS. The 3 SS specimens with SNHL showed pathologic changes in the SV similar to the mouse model of autoimmune inner ear disease. Additionally, we propose that spiral ganglia neurons may be directly affected by SS pathology. These results highlight the importance of correlating the histopathology of human temporal bones with animal models to better understand inner ear disease in future research.

The spectrum of large granular lymphocyte leukemia and Felty's syndrome.

PURPOSE OF REVIEW: Patients with chronic large granular lymphocyte (LGL) leukemia often have rheumatoid arthritis (RA), neutropenia and splenomegaly, thereby resembling the manifestations observed in patients with Felty's syndrome, which is a rare complication of RA characterized by neutropenia and splenomegaly. Both entities have similar clinical and laboratory presentation, as well as a common genetic determinant, HLA-DR4, indicating they may be part of the same disease spectrum. This review paper seeks to discuss the underlying pathogenesis and therapeutic algorithm of RA, neutropenia and splenomegaly in the spectrum of LGL leukemia and Felty's syndrome. RECENT FINDINGS: We hypothesize that there may be a common pathogenic mechanism between LGL leukemia and typical Felty's syndrome. Phenotypic and functional data have strongly suggested that CD3 LGL leukemia is antigen-activated. Aberrations in the T-cell repertoire with the emergence of oligoclonal/clonal lymphoid populations have been found to play a pivotal role in pathogenesis of RA. The biologic properties of the pivotal T cell involved in RA pathogenesis are remarkably similar to those in leukemic LGL. SUMMARY: RA-associated T-cell LGL leukemia and articular manifestations of typical Felty's syndrome are not distinguishable. A common pathogenetic link between LGL leukemia and RA is proposed.

High avidity cytokine autoantibodies in health and disease: pathogenesis and mechanisms.

Numerous reports have documented the presence of autoantibodies working against naturally occurring cytokines in humans in health and disease. In most instances, their physiological and pathophysiological significance remains unknown. However, recent advances in the methodologies for detecting cytokine autoantibodies and their application in research focused on specific disorders have shown that some cytokine autoantibodies play an important role in the pathogenesis of disease. Additionally, levels of cytokine autoantibodies may also correlate with disease severity and progression in certain infectious and autoimmune diseases but not in others. This suggests that cytokine-specific pathogenic differences exist. While multiple lines of evidence support the notion that high avidity cytokine autoantibodies are present and likely to be ubiquitous in healthy individuals, their potential physiological role, if any, is less clear. It is believed that they may function by scavenging pro-inflammatory cytokines and thereby inhibiting deleterious 'endocrine' effects, or by serving as carrier proteins, providing a 'reservoir' of inactive cytokines and thus modulating cytokine bioactivity. A central hypothesis is that sustained or repeated high-level exposure to cytokines triggers defects in T-cell tolerance, resulting in the expansion of existing cytokine autoantibody-producing B cells.

Leg ulcer and thigh telangiectasia associated with natural killer cell CD56(-) large granular lymphocyte leukemia in a patient with pseudo-Felty syndrome.

Clonal disorders of large granular lymphocytes (LGL) represent a rare spectrum of biologically distinct lymphoproliferative diseases originating either from mature T cells or natural killer cells. Both subtypes can manifest as indolent or aggressive disorders. We report a 77-year-old woman with rheumatoid arthritis, splenomegaly, and neutropenia who developed a painful leg ulcer refractory to treatment and thigh telangiectatic lesions. Because of the association of rheumatoid arthritis, splenomegaly, and nonspecific neutropenia, the diagnosis of Felty syndrome was initially made. Further investigation allowed the diagnosis of a CD56(-) natural killer-cell LGL leukemia and documented skin infiltration by natural killer cells. Cutaneous manifestations of LGL leukemia have been rarely reported. This report of pseudo-Felty syndrome with CD56(-) LGL leukemia, presenting with a leg ulcer and telangiectasia, enhances the role of dermatology in the diagnosis of hematologic neoplasia.

The impact of HLA-DRB1 genes on extra-articular disease manifestations in rheumatoid arthritis.

The objective of this study was to examine HLA-DRB1 and HLA-DQB1 genotypes in patients with severe extra-articular rheumatoid arthritis (ExRA) and to compare them with the genotypes of rheumatoid arthritis (RA) patients without extra-articular manifestations. Patients with severe ExRA were recruited from a large research database of patients with RA, from two cohorts of prevalent RA cases, and from a regional multicenter early RA cohort. Cases with ExRA manifestations (n = 159) were classified according to predefined criteria. Controls (n = 178) with RA but no ExRA were selected from the same sources. Cases and controls were matched for duration of RA and for clinical center. PCR based HLA-DRB1 and HLA-DQB1 genotyping was performed using the Biotest SSP kit, with additional sequencing in order to distinguish DRB1*04 subtypes. Associations between alleles and disease phenotypes were tested using multiple simulations of random distributions of alleles. There was no difference in global distribution of HLA-DRB1 and HLA-DQB1 alleles between patients with ExRA and controls. DRB1*0401 (P = 0.003) and 0401/0401 homozygosity (P = 0.002) were more frequent in Felty's syndrome than in controls. The presence of two HLA-DRB1*04 alleles encoding the shared epitope (SE) was associated with ExRA (overall odds ratio 1.79, 95% confidence interval 1.04-3.08) and with rheumatoid vasculitis (odds ratio 2.44, 95% confidence interval 1.22-4.89). In this large sample of patients with ExRA, Felty's syndrome was the only manifestation that was clearly associated with HLA-DRB1*0401. Other ExRA manifestations were not associated with individual alleles but with DRB1*04 SE double dose genotypes. This confirms that SE genes contribute to RA disease severity and ExRA. Other genetic and environmental factors may have a more specific impact on individual ExRA manifestations.

Longterm outcome of treatment of Felty's syndrome with intramuscular gold: case reports and recommendations for management.

OBJECTIVE: To evaluate the incidence, complications, and course of Felty's syndrome (FS) in patients treated with intramuscular (IM) gold. METHODS: Retrospective chart review of all FS cases (1979 to 2003) was conducted in the Mary Pack Arthritis Centre (MPAC) gold clinic. FS was diagnosed if patients had rheumatoid arthritis (RA; American College of Rheumatology criteria) and persistent leukopenia [white blood cell (WBC) count < 4] in the absence of other known causes of leukopenia. Splenomegaly was not part of the inclusion criteria. RESULTS: Thirteen patients with FS were identified in the gold clinic population. The mean age at diagnosis of FS was 58.7 years and the mean duration of RA at time of diagnosis was 6.9 years. The weekly dose of gold ranged from 10 mg to 50 mg depending on tolerability. Gold therapy resulted in normalization of the WBC count in 9 of 13 patients. The mean time to normalization of the WBC was 40 weeks. Only one patient with FS had experienced recurrent infectious complications from FS, and this did not recur after gold treatment was initiated. No patient had vasculitis. CONCLUSION: In our gold clinic population FS is a mild disease and is rarely associated with infectious complications. Gold is an effective treatment of FS.

Felty's syndrome.

Felty's syndrome (FS) comprises a triad of rheumatoid arthritis (RA), neutropenia and splenomegaly, occurring in less than 1% of RA patients. Clinically it is characterized by severe joint destruction contrasting with moderate or absent joint inflammation and severe extra-articular disease, including a high frequency of rheumatoid nodules, lymphadenopathy, hepatopathy, vasculitis, leg ulcers, skin pigmentation etc. Recurrent bacterial infections are mostly due to the severe, otherwise unexplained neutropenia. The cause of neutropenia lies in both decreased granulopoiesis and increased peripheral destruction of granulocytes. Recurrent infections may lead to increased mortality. Spontaneous remission of the syndrome also occurs. Over 95% of FS patients are positive for rheumatoid factor (RF), 47-100% are positive for antinuclear antibody (ANA), and 78% of patients have the HLA-DR4*0401 antigen. Some 30% of FS patients have large granular lymphocyte (LGL) expansion. LGL expansion associated with uncomplicated RA is immunogenetically and phenotypically very similar to but clinically different from FS. Neutropenia of FS can be effectively treated with disease-modifying anti-rheumatic drugs (DMARDs), the widest experience being with methotrexate (MTX). Results of treatment with granulocyte colony-stimulating factor (G-CSF) are encouraging, but there is no experience with other biological agents. Splenectomy results in immediate improvement of neutropenia in 80% of the patients, but the rate of infection decreases to a lesser degree.

Association of autoantibodies to glucose-6-phosphate isomerase with extraarticular complications in rheumatoid arthritis.

OBJECTIVE: In the K/BxN mouse model, autoantibodies against glucose-6-phosphate isomerase (GPI) cause arthritis. The relevance of this model for human disease remains a subject of controversy. We set out to determine whether GPI autoantibodies occur in patients with rheumatoid arthritis (RA) and, if so, at what stage of the RA. METHODS: Using an enzyme-linked immunosorbent assay, serum from 131 RA patients and 28 healthy controls was tested for autoantibodies against recombinant human GPI. Patients were grouped according to disease duration and presence of rheumatoid nodules, rheumatoid vasculitis, and Felty's syndrome, which are extraarticular complications of RA. RESULTS: Elevated levels of autoantibodies against GPI were present in 5% of patients with uncomplicated RA and 4% of controls. In RA complicated by extraarticular manifestations, anti-GPI antibodies were observed in 18% of patients with rheumatoid nodules, 45% of patients with rheumatoid vasculitis, and 92% of patients with Felty's syndrome. CONCLUSION: In patients with RA, autoantibodies to GPI are associated with the occurrence of extraarticular complications.