Autoantibodies against granulocyte colony-stimulating factor in Felty's syndrome and neutropenic systemic lupus erythematosus

Anti-cytokine autoantibodies: mechanistic insights and disease associations

Anti-cytokine autoantibodies (ACAAs) are increasingly recognized as modulating disease severity in infection, inflammation and autoimmunity. By reducing or augmenting cytokine signalling pathways or by altering the half-life of cytokines in the circulation, ACAAs can be either pathogenic or disease ameliorating. The origins of ACAAs remain unclear. Here, we focus on the most common ACAAs in the context of disease groups with similar characteristics. We review the emerging genetic and environmental factors that are thought to drive their production. We also describe how the profiling of ACAAs should be considered for the early diagnosis, active monitoring, treatment or sub-phenotyping of diseases. Finally, we discuss how understanding the biology of naturally occurring ACAAs can guide therapeutic strategies.

Felty's syndrome

Felty's syndrome was first described in 1924 by the US-American physician Augustus Roi Felty as a triad of rheumatoid arthritis, splenomegaly and leucopenia. Even nearly 100 years later, this rare syndrome is still paralleled by diagnostic and therapeutic challenges and its pathogenesis is incompletely understood. Neutropenia with potentially life-threatening infections is the main problem and several pathomechanisms like Fas-mediated apoptosis, anti-neutrophil antibodies, anti-G-CSF antibodies, neutrophil consumption in the context of NETosis and suppression of granulopoiesis by T-LGLs have been suggested. Felty's syndrome has various differential diagnoses as splenomegaly and cytopenia are common features of different infectious diseases, malignancies and autoimmune disorders. Additionally, benign clonal T-/NK-LGL lymphocytosis is increasingly noticed in Felty's syndrome, which further complicates diagnosis. Today's treatment options are still sparse and are largely based on case reports and small case series. Methotrexate is the mainstay of therapy, followed by rituximab, but there is less evidence for alternatives in the case of adverse reactions or failure of these drugs. This article gives an updated review about Felty's syndrome including its pathogenesis and treatment options.

The Use of Abatacept for the Treatment of Felty Syndrome in Rheumatoid Arthritis

Felty syndrome is characterized by a triad of rheumatoid arthritis, neutropenia, and splenomegaly that typically occurs in patients with seropositive rheumatoid arthritis. We report a case of an 81-year-old man with a 22-year history of rheumatoid arthritis who developed pancytopenia and neutropenia for one month. An abdominal ultrasound revealed splenomegaly. A bone marrow biopsy excluded large granular lymphocytic leukemia, thus Felty Syndrome was diagnosed. He was treated with a maximum tolerated dose of methotrexate (15 mg once a week) for two months with no improvement in absolute neutrophil count. The patient was given abatacept 1000 mg intravenously every four weeks with improvement in hemoglobin, leukocyte, and platelet counts and absolute neutrophil counts from 0.2 to 2.4 K/µl.

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.

Autoantibodies in immunodeficiency syndromes: The Janus faces of immune dysregulation

Immunodeficiency syndromes represent a diverse group of inherited and acquired disorders, characterized by a spectrum of clinical manifestations, including recurrent infections, autoimmunity, lymphoproliferation and malignancy. Autoantibodies against various self-antigens reflect the immune dysregulation underlying these disorders, and could contribute to certain clinical findings, such as susceptibility to opportunistic infections, cytopenia of different hematopoietic lineages, and organ-specific autoimmune diseases. The mechanism of autoantibody production in the context of immunodeficiency remains largely unknown but is likely shaped by both intrinsic genetic aberrations and extrinsic exposures to possible infectious agents. These autoantibodies if harbor neutralizing activities and reach certain levels in the circulation, could disrupt the biological functions of their targets, resulting in specific clinical manifestations. Herein, we reviewed the prevalence of autoantibodies against cytokines, hematopoietic cells and organ-specific antigens in immunodeficiency syndromes and examined their associations with certain clinical findings. Moreover, the potential mechanism of autoantibody production was also discussed. These may shed light on the development of mechanism-based therapies to reset the dysregulated immune system in immunodeficient patients.

[Anti-cytokine autoantibodies: Review of the literature]

Anti-cytokine antibodies (ACA) are an emerging cause of acquired immunodeficiency, especially in previously healthy adults. The most frequently reported are anti-IFN-γ responsible for disseminated non-tuberculous mycobacteria infections, and anti-GM-CSF mainly in mycobacteria, cryptococcosis and nocardiosis infections. The presence of anti-IFN-α in severe COVID-19 infections has recently been described. The search for and detection of these ACAs in an unusual infection situation makes it possible to set up specific therapies in addition to the anti-infective treatment. ACAs are also frequent in various autoimmune pathologies where, in addition to being indicators of the breakdown of immune tolerance, they can modulate the activity of the disease according to their cytokine target. In this review of the literature, we will focus on the epidemiology and the clinical impact of these ACAs in healthy subjects and in infectious or dysimmune diseases.

Anti-Interferon Autoantibodies in Adult-Onset Immunodeficiency Syndrome and Severe COVID-19 Infection

Adult-onset immunodeficiency syndrome due to anti-interferon (IFN)-γ autoantibodies has attracted much attention in recent years. It usually occurs in previously healthy people and usually presents as chronic, recurrent, and hard-to-control infections that can be effectively treated with aggressive antibiotic therapy. Adult-onset immunodeficiency syndrome is also referred to as AIDS-like syndrome. Anti-type I IFN (IFN-I) autoantibodies have been reported to play a significant role in the pathogenesis of coronavirus disease 2019 (COVID-19) and preexisting anti-IFN-I autoantibodies are associated with an increased risk of severe COVID-19. This review summarizes the effects of anti-IFN autoantibodies on the susceptibility and severity of various infectious diseases, including SARS-CoV-2 infection. In addition, we discuss the role of anti-IFN autoantibodies in the pathogenesis of autoimmune diseases that are characterized by recurrent infections.

The Role of GM-CSF Autoantibodies in Infection and Autoimmune Pulmonary Alveolar Proteinosis: A Concise Review

Autoantibodies to multiple cytokines have been identified and some, including antibodies against granulocyte-macrophage colony-stimulating factor (GM-CSF), have been associated with increased susceptibility to infection. High levels of GM-CSF autoantibodies that neutralize signaling cause autoimmune pulmonary alveolar proteinosis (aPAP), an ultrarare autoimmune disease characterized by accumulation of excess surfactant in the alveoli, leading to pulmonary insufficiency. Defective GM-CSF signaling leads to functional deficits in multiple cell types, including macrophages and neutrophils, with impaired phagocytosis and host immune responses against pulmonary and systemic infections. In this article, we review the role of GM-CSF in aPAP pathogenesis and pulmonary homeostasis along with the increased incidence of infections (particularly opportunistic infections). Therefore, recombinant human GM-CSF products may have potential for treatment of aPAP and possibly other infectious and pulmonary diseases due to its pleotropic immunomodulatory actions.

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.

Non-Articular Felty Syndrome Refractory to Granulocyte Colony-Stimulating Factor Therapy

Felty syndrome (FS), an uncommon manifestation seen in patients with rheumatoid arthritis (RA), usually presents as a triad of erosive arthritis, splenomegaly, and neutropenia. It is extremely rare for RA to present as FS or develop after initially presenting as neutropenia and splenomegaly. In this report, we describe a case of a 55-year-old woman who initially presented with fever and vaginal pain. Her sepsis workup revealed genital herpes in the setting of leukopenia, with an incidental finding of splenomegaly on imaging. The patient was managed with filgrastim and valacyclovir. Two weeks later, she presented again with pleuritic chest pain and worsening leukopenia. This led to an extensive workup by the hematology team to diagnose and confirm the diagnosis of FS. We also engage in a review of the existing literature of such cases and emphasize the importance of serological testing for RA in patients with leukopenia and splenomegaly, even in the absence of joint symptoms or prior diagnosis of RA. The management should be guided towards treating the infection, correcting the neutropenia, and treating the underlying chronic disease.

The combined prevalence of classified rare rheumatic diseases is almost double that of ankylosing spondylitis

BACKGROUND

Rare diseases (RDs) affect less than 5/10,000 people in Europe and fewer than 200,000 individuals in the United States. In rheumatology, RDs are heterogeneous and lack systemic classification. Clinical courses involve a variety of diverse symptoms, and patients may be misdiagnosed and not receive appropriate treatment. The objective of this study was to identify and classify some of the most important RDs in rheumatology. We also attempted to determine their combined prevalence to more precisely define this area of rheumatology and increase awareness of RDs in healthcare systems. We conducted a comprehensive literature search and analyzed each disease for the specified criteria, such as clinical symptoms, treatment regimens, prognoses, and point prevalences. If no epidemiological data were available, we estimated the prevalence as 1/1,000,000. The total point prevalence for all RDs in rheumatology was estimated as the sum of the individually determined prevalences.

RESULTS

A total of 76 syndromes and diseases were identified, including vasculitis/vasculopathy (n = 15), arthritis/arthropathy (n = 11), autoinflammatory syndromes (n = 11), myositis (n = 9), bone disorders (n = 11), connective tissue diseases (n = 8), overgrowth syndromes (n = 3), and others (n = 8). Out of the 76 diseases, 61 (80%) are classified as chronic, with a remitting-relapsing course in 27 cases (35%) upon adequate treatment. Another 34 (45%) diseases were predominantly progressive and difficult to control. Corticosteroids are a therapeutic option in 49 (64%) syndromes. Mortality is variable and could not be determined precisely. Epidemiological studies and prevalence data were available for 33 syndromes and diseases. For an additional eight diseases, only incidence data were accessible. The summed prevalence of all RDs was 28.8/10,000.

CONCLUSIONS

RDs in rheumatology are frequently chronic, progressive, and present variable symptoms. Treatment options are often restricted to corticosteroids, presumably because of the scarcity of randomized controlled trials. The estimated combined prevalence is significant and almost double that of ankylosing spondylitis (18/10,000). Thus, healthcare systems should assign RDs similar importance as any other common disease in rheumatology.

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.

Porto-Sinusoidal Vascular Disease as the Cause of Portal Hypertension in Felty's Syndrome: A Case Report and Literature Review

Felty's syndrome (FS) is a disorder wherein patients with rheumatoid arthritis develop splenomegaly, neutropenia, and in some cases, portal hypertension without underlying cirrhosis. Esophageal variceal bleeding is a complication of FS in patients with portal hypertension. In contrast to splenectomy, few reports exist on the management of variceal bleeding with endoscopic therapy. Moreover, the long-term outcome has not been reported. We present a patient with esophageal variceal bleeding due to portal hypertension secondary to Felty's syndrome. The patient was followed up for two years postendoscopy intervention. Literature review was performed and the histological features of portal hypertension in FS are discussed. The patient presented with a typical triad of rheumatoid arthritis (RA), splenomegaly, and neutropenia and was diagnosed as Felty's syndrome in 2012. She was admitted to our hospital in September 2017 for esophageal variceal bleeding. At the time of admission, her liver function test was normal. Abdominal CT showed no signs of cirrhosis and portal vein obstruction. Liver biopsy further excluded diagnosis of cirrhosis and supported the diagnosis of porto-sinusoidal vascular disease (PSVD), which was previously named as noncirrhotic idiopathic portal hypertension (NCIPH). An upper abdominal endoscopy revealed gastric and esophageal varices. A series of endoscopies was performed to ligate the esophageal varices. The patient was followed up for two years and did not show rebleeding. In conclusion, comorbid PSVD might be a cause of portal hypertension in FS patients. The present case had excellent outcome in two years, which supported the use of endoscopic therapy for the management of variceal bleeding in FS patients. Further large prospective study is needed to confirm the findings.

Functional Analysis of Anti-cytokine Autoantibodies Using Flow Cytometry

Autoantibodies to cytokines are increasingly being detected in association with immunodeficient, autoimmune and immune dysregulated states. Presence of these autoantibodies in an otherwise healthy individual may result in a unique phenotype characterized by predisposition to infection with specific organisms. The ability to detect these autoantibodies is of importance as it may direct treatment toward a combination of anti-microbial agents and immunomodulatory therapies that decrease autoantibody levels, thereby releasing the immune system from autoantibody-mediated inhibition. Ligand binding assays such as ELISA or bead multiplex assays have been used to detect these antibodies. However, not all anti-cytokine autoantibodies have demonstrable function in vitro and therefore their clinical significance is unclear. Assays that evaluate the functionality of anti-cytokine autoantibodies can supplement such ligand binding assays and add valuable functional information that, when viewed in the context of the clinical phenotype, may guide the use of adjunctive immunomodulatory therapy. This mini review provides an overview of anti-cytokine autoantibodies identified to date and their clinical associations. It also describes the use of flow cytometry for the functional analysis of anti-IFNγ and anti-GM-CSF autoantibodies.

Neutropaenia and splenomegaly without arthritis: think rheumatoid arthritis

Felty syndrome(FS) is an uncommon, but severe, extra-articular manifestation of rheumatoid arthritis (RA). It occurs in patients with longstanding RA. It is extremely rare for RA to present as FS or develop after initially presenting as neutropaenia and splenomegaly. We describe a case of 47-year-old woman who was diagnosed simultaneously with FS and possible RA after testing positive for anticyclic citrullinated peptide antibody, but a negative rheumatoid factor. She had an excellent response to methotrexate. We review the existing literature of such cases and emphasise the importance of serological testing for RA in patients presenting with neutropaenia and splenomegaly, even in the absence of joint symptoms or prior diagnosis of RA.

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Zusammenfassung. Das Felty-Syndrom ist eine komplizierte und seltene Form der rheumatoiden Arthritis mit Splenomegalie und Neutropenie, das von A. R. Felty im Jahr 1924 erstmals beschrieben wurde und dessen Diagnose klinisch gestellt wird. Das Felty-Syndrom geht mit hoher Entzündungs- und regelmässig hoher Krankheitsaktivität einher. Die Prognose ist aufgrund der hohen Inzidenz von Infekten schlecht. Die Ursache ist noch unklar; diskutiert werden eine chronische Entzündungsreaktion und eine entsprechende individuelle Disposition. Differenzialdiagnostisch müssen maligne Erkrankungen des Blutes ausgeschlossen werden. Die Therapie der Wahl ist Methotrexat, bei fehlendem Ansprechen können andere DMARDs (Disease-Modifying Anti-Rheumatic Drugs) in Erwägung gezogen werden; die Therapie mit Steroiden in der akuten Infektsituation ist kontrovers. Weitere Therapieoptionen wurden bisher nur in kleinen Fallstudien beschrieben. Von TNF-α-Inhibitoren wurde in einer Kleinstudie mit sechs Patienten über Unwirksamkeit berichtet. Der CD-20-Antagonist Rituximab (Mabthera®) hat in einer Studie mit acht Patienten bei der Mehrheit (n = 5) einen Anstieg der neutrophilen Granulozyten gezeigt. Als Wirkmechanismus wird eine Einflussnahme auf Anti-G-CSF-Antikörper diskutiert.

Distinct Functions of Autoantibodies Against Interferon in Systemic Lupus Erythematosus: A Comprehensive Analysis of Anticytokine Autoantibodies in Common Rheumatic Diseases

OBJECTIVE

Anticytokine autoantibodies occur across a range of hematologic, pulmonary, and infectious diseases. However, systematic investigation of their presence and significance in autoimmune diseases is lacking. This study was undertaken to examine the distinct functions of anticytokine autoantibodies in patients with systemic lupus erythematosus (SLE) compared to patients with other rheumatic diseases and healthy controls.

METHODS

Serum samples from patients with SLE (n = 199), patients with primary Sjögren's syndrome (SS) (n = 150), patients with rheumatoid arthritis (RA) (n = 149), and healthy controls (n = 200) were screened for 24 anticytokine autoantibodies using a multiplex bead-based assay. To evaluate the biologic activity of anticytokine autoantibodies, their ability to block cytokine-induced signal transduction or protein expression was measured. RNA sequencing was performed on whole blood in a subset of healthy controls and patients with SLE.

RESULTS

Patients with SLE and those with SS had a striking excess of autoantibodies against interferons and the interferon-responsive chemokine interferon-inducible protein 10 (IP-10). Only autoantibodies against type I interferon, interleukin-12 (IL-12), and IL-22 exhibited neutralizing activity. In SLE, the presence of anti-interferon-γ autoantibodies was correlated with more severe disease activity, higher levels of anti-double-stranded DNA antibodies, and elevated expression of interferon-α/β-inducible genes. Conversely, in SLE patients with blocking anti-interferon-α autoantibodies, the type I interferon gene expression signature was normalized. Anti-type III interferon autoantibodies (λ2, λ3) and anti-IP-10 autoantibodies were newly recognized in SLE patient serum, and autoantibodies against macrophage-colony stimulating factor, IL-4, IL-7, IL-17, and IL-22, none of which have been previously identified in rheumatic conditions, were discovered.

CONCLUSION

Anticytokine autoantibodies are associated with distinct patterns of disease in SLE, SS, and RA. Anti-interferon autoantibodies are overrepresented in patients with SLE and those with SS, and fall into distinct functional classes, with only a subset of anti-type I interferon antibodies exhibiting neutralizing activity. Anti-interferon-γ autoantibodies are correlated with increased disease activity and interferon-related gene expression, suggesting that such autoantibodies may contribute to the pathogenesis of SLE.

Production of pure fractions of immunoglobulin G subclass autoantibodies against tumor necrosis factor

Autoantibodies directed against cytokines are important effector molecules regulating the biological activity of cytokines. There is experimental evidence indicating that autoantibodies belonging to different immunoglobulin G (IgG) subclasses may have different functional activity. The purpose of this work was to develop a protocol for the purification of fractions of IgG subclass antibodies directed against tumor necrosis factor (TNF). We developed a series of steps, including gel filtration, positive and negative affinity chromatography, and ultrafiltration, to achieve this goal. Our protocol purified IgG subclass autoantibodies directed against TNF from a human immunoglobulin preparation. The isolation of these anti-TNF autoantibodies will enable evaluation of the effect of TNF-specific antibodies on TNF biological activity. Our newly developed technique for purifying subclasses of anti-TNF autoantibodies may be important for both basic research on the functional activity of these autoantibodies and for clinical immunology.

Pure White Cell Aplasia and Necrotizing Myositis

Pure white cell aplasia (PWCA) is a rare hematologic disorder characterized by the absence of neutrophil lineages in the bone marrow with intact megakaryopoiesis and erythropoiesis. PWCA has been associated with autoimmune, drug-induced, and viral exposures. Here, we report a case of a 74-year-old female who presented with severe proximal weakness without pain and was found to have PWCA with nonspecific inflammatory necrotizing myositis and acute liver injury on biopsies. These findings were associated with a recent course of azithromycin and her daily use of a statin. Myositis improved on prednisone but PWCA persisted. With intravenous immunoglobulin and granulocyte-colony stimulating factor therapies, her symptoms and neutrophil counts improved and were sustained for months.

Anticytokine Autoantibodies: Association with Infection and Immune Dysregulation

The association of autoantibodies to cytokines with immune deficiency, autoimmunity and/or immune dysregulation is increasingly being recognized. For example, autoantibodies to interferon gamma have been found to be associated with chronic, treatment refractory infections with intracellular organisms such as mycobacteria, autoantibodies to interleukin 17 with chronic mucocutaneous candidiasis, and anti-interferon alpha autoantibodies with systemic lupus erythematosus. While low titer autoantibodies to these and other cytokines may be detected in normal individuals, patients with infectious or autoimmune manifestations tend to have high titer autoantibodies that may block or potentiate the function of the respective cytokine. Recognition of these autoantibodies is important because it may direct treatment toward a combination of adjunctive immunotherapy to modulate the autoantibody level while continuing with appropriate anti-microbial therapy. This review focuses on the anti-cytokine autoantibodies documented to date, their autoimmune, immune dysregulation and infectious disease associations, methods for detection of these antibodies and potential treatment options.

Protein microarrays identify disease-specific anti-cytokine autoantibody profiles in the landscape of immunodeficiency

BACKGROUND

Anti-cytokine autoantibodies (ACAAs) are pathogenic in a handful of rare immunodeficiencies. However, the prevalence and significance of other ACAAs across immunodeficiencies have not yet been described.

OBJECTIVE

We profiled ACAAs in a diverse cohort of serum samples from patients with immunodeficiency and assessed the sensitivity and specificity of protein microarrays for ACAA identification and discovery.

METHODS

Highly multiplexed protein microarrays were designed and fabricated. Blinded serum samples from a cohort of 58 immunodeficiency patients and healthy control subjects were used to probe microarrays. Unsupervised hierarchical clustering was used to identify clusters of reactivity, and after unblinding, significance analysis of microarrays was used to identify disease-specific autoantibodies. A bead-based assay was used to validate protein microarray results. Blocking activity of serum containing ACAAs was measured in vitro.

RESULTS

Protein microarrays were highly sensitive and specific for the detection of ACAAs in patients with autoimmune polyendocrine syndrome type I and pulmonary alveolar proteinosis, detecting ACAA levels consistent with those reported in the published literature. Protein microarray results were validated by using an independent bead-based assay. To confirm the functional significance of these ACAAs, we tested and confirmed the blocking activity of select ACAAs in vitro.

CONCLUSION

Protein microarrays are a powerful tool for ACAA detection and discovery, and they hold promise as a diagnostic for the evaluation and monitoring of clinical immunodeficiency.

Understanding chronic neutropenia: life is short

The pathophysiological mechanisms underlying chronic neutropenia are extensive, varying from haematopoietic stem cell disorders resulting in defective neutrophil production, to accelerated apoptosis of neutrophil progenitors or circulating mature neutrophils. While the knowledge concerning genetic defects associated with congenital neutropenia or bone marrow failure is increasing rapidly, the functional role and consequences of these genetic alterations is often not well understood. In addition, there is a large group of diseases, including primary immunodeficiencies and metabolic diseases, in which chronic neutropenia is one of the symptoms, while there is no clear bone marrow pathology or haematopoietic stem cell dysfunction. Altogether, these disease entities illustrate the complexity of normal neutrophil development, the functional role of the (bone marrow) microenvironment and the increased propensity to undergo apoptosis, which is typical for neutrophils. The large variety of disorders associated with chronic neutropenia makes classification almost impossible and possibly not desirable, based on the clinical phenotypes. However, a better understanding of the regulation of normal myeloid differentiation and neutrophil development is of great importance in the diagnostic evaluation of unexplained chronic neutropenia. In this review we propose insights in the pathophysiology of chronic neutropenia in the context of the functional role of key players during normal neutrophil development, neutrophil release and neutrophil survival.

Practice parameter for the diagnosis and management of primary immunodeficiency

The American Academy of Allergy, Asthma & Immunology (AAAAI) and the American College of Allergy, Asthma & Immunology (ACAAI) have jointly accepted responsibility for establishing the "Practice parameter for the diagnosis and management of primary immunodeficiency." This is a complete and comprehensive document at the current time. The medical environment is a changing environment, and not all recommendations will be appropriate for all patients. Because this document incorporated the efforts of many participants, no single individual, including those who served on the Joint Task Force, is authorized to provide an official AAAAI or ACAAI interpretation of these practice parameters. Any request for information about or an interpretation of these practice parameters by the AAAAI or ACAAI should be directed to the Executive Offices of the AAAAI, the ACAAI, and the Joint Council of Allergy, Asthma & Immunology. These parameters are not designed for use by pharmaceutical companies in drug promotion.

The role of intravenous immunoglobulins in the treatment of rheumatoid arthritis

Intravenous immunoglobulins (IVIGs) are beneficial and safe for various diseases other than primary immunodeficiencies. Over the years, IVIG has been given for autoimmune diseases as an off-label adjunct therapy. While other biologic agents are indicated for rheumatoid arthritis (RA), IVIG may have a role for specific subgroups of RA patients where anti-cytokine blockers or rituximab may be unwarranted. Such subgroups may include patients with vasculitis, overlap rhupus syndrome, severe infections with active disease, and pregnancy. In addition, IVIG may be considered for juvenile chronic arthritis (JCA) and adult Still's disease. We review the literature for IVIG treatment in RA patients and for these subgroups.

[Rituximab for treatment of Felty’s syndrome]

Felty’s syndrome is a rare variant of severe seropositive rheumatoid arthritis with neutropenia and splenomegaly. It is difficult to treat and associated with a poor prognosis due to the substantial risk of infections. This article presents the case of a patient with refractory disease who responded to rituximab with permanent normalization of neutrophil counts. Repeated infusions were necessary to induce and maintain remission.

Emerging clinical phenotypes associated with anti-cytokine autoantibodies

Anti-cytokine autoantibodies (AAbs) are frequent and involve a very large panel of cytokines both in healthy subjects and in patients with various pathological conditions. In healthy individuals, anti-cytokine AAbs are described as a part of the natural AAb repertoire and are thought to contribute to the fine regulation of cytokine homeostasis. In some patients, neutralizing AAbs targeting cytokines required for the immune protection against specific microbes may induce acquired immunodeficiency leading to very specific infectious phenotypes. For instance, anti-IFNγ AAbs may induce disseminated non-tuberculous mycobacterial infections; anti-IL-17 AAbs are associated with the development of chronic mucosal candidiasis, and anti-IL-6 AAbs with severe staphylococcal or streptococcal infections. In patients with autoimmune diseases, AAbs directed against pathogenic cytokines are able to influence the course of the diseases. In lupus patients, neutralizing anti-IFNα and anti-TNFα AAbs are associated with a decreased bioactivity of the corresponding cytokine and a lower disease severity. Similarly, anti-IL-1α AAbs are associated with nondestructive forms of chronic polyarthritis. More surprisingly, neutralizing anti-BAFF AAbs are observed in the serum of lupus patients with elevated IFNα signature and higher disease activity. In this review, we summarize the current literature describing the different phenotypes and the main mechanisms associated with the occurrence of anti-cytokine AAbs.

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.

Presentation of three cases followed up with a diagnosis of Felty syndrome

An effective treatment strategy for Felty syndrome (FS) has not been developed so far. In this article, three cases with FS, who responded to different treatment modalities, have been presented. Case 1 was a 52-year-old male patient who initially received methotrexate, and then, he was switched to granulocyte colony-stimulating factor (G-CSF) and cyclosporine treatment when his neutropenia was further deteriorated. The patient needed monthly doses of G-CSF for nearly 6 months, and his steroid dose was increased. Afterwards, his neutropenia improved with cyclosporine, methotrexate, and hydroxychloroquine combination treatment. Case 2 was a 78-year-old female patient who was started on leflunomide, hydroxychloroquine, and 60 mg methylprednisolone. Case 3 was a 69-year-old female patient who was first treated with 32 mg methylprednisolone, G-CSF, and then with cyclosporine. Neutropenia of both patients improved, and their health status normalized at 2 months. Different treatment strategies have been tried for the management of FS; disease-modifying anti-rheumatic drugs have been used successfully alone or in combination with G-CSF. As seen in the last case, it should be kept in mind that patients can present predominantly with symptoms of infection or hematologic disorders.

Detection of anti-cytokine antibodies and their clinical relevance

Cytokines regulate many aspects of cell growth and differentiation and play pivotal roles in the orchestration of immune defence against invading pathogens. Though 'self' proteins, they are potentially immunogenic and can give rise to anti-cytokine autoantibodies (aCA). The main foci of the article are a critical summary of the various methodologies applied for detecting and measuring aCA and a broad review of studies of the occurrence, characterization and clinical relevance of aCA in normal healthy individuals, patients with autoimmune diseases or microbial infections and aCA in patients whose disease is treated with recombinant cytokine products. The need for technical and methodological improvement of assays, including validation and standardization, together with approaches to harmonize calculation and reporting of results is also discussed.

Autoantibodies induced by chimeric cytokine-HIV envelope glycoprotein immunogens

Cytokines are often used as adjuvants to increase the immunogenicity of vaccines because they can improve the immune response and/or direct it into a desired direction. As an alternative to codelivering Ags and cytokines separately, they can be fused into a composite protein, with the advantage that both moieties act on the same immune cells. The HIV-1 envelope glycoprotein (Env) spike, located on the outside of virus particles and the only relevant protein for the induction of neutralizing Abs, is poorly immunogenic. The induction of anti-Env Abs can be improved by coupling Env proteins to costimulatory molecules such as a proliferation inducing ligand (APRIL). In this study, we evaluated the immunogenicity of chimeric molecules containing uncleaved Env gp140 fused to the species-matched cytokines IL-21 or GM-CSF in rabbits and mice. Each cytokine was either fused to the C terminus of Env or embedded within Env at the position of the variable loops 1 and 2. The cytokine components of the chimeric Env-GM-CSF and Env-IL-21 molecules were functional in vitro, but none of the Env-cytokine fusion proteins resulted in improved Ab responses in vivo. Both the Env-GM-CSF and the Env-IL-21 molecules induced strong anticytokine Ab responses in both test species. These autoimmune responses were independent of the location of the cytokine in the chimeric Env molecules in that they were induced by cytokines inserted within the variable loops 1 and 2 of Env or fused to its C terminus. The induction of undesired autoimmune responses should be considered when using cytokines as costimulatory molecules in fusion proteins.

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.

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.

Protein microarray analysis reveals BAFF-binding autoantibodies in systemic lupus erythematosus

Autoantibodies against cytokines, chemokines, and growth factors inhibit normal immunity and are implicated in inflammatory autoimmune disease and diseases of immune deficiency. In an effort to evaluate serum from autoimmune and immunodeficient patients for Abs against cytokines, chemokines, and growth factors in a high-throughput and unbiased manner, we constructed a multiplex protein microarray for detection of serum factor-binding Abs and used the microarray to detect autoantibody targets in SLE. We designed a nitrocellulose-surface microarray containing human cytokines, chemokines, and other circulating proteins and demonstrated that the array permitted specific detection of serum factor-binding probes. We used the arrays to detect previously described autoantibodies against cytokines in samples from individuals with autoimmune polyendocrine syndrome type 1 and chronic mycobacterial infection. Serum profiling from individuals with SLE revealed that among several targets, elevated IgG autoantibody reactivity to B cell-activating factor (BAFF) was associated with SLE compared with control samples. BAFF reactivity correlated with the severity of disease-associated features, including IFN-α-driven SLE pathology. Our results showed that serum factor protein microarrays facilitate detection of autoantibody reactivity to serum factors in human samples and that BAFF-reactive autoantibodies may be associated with an elevated inflammatory disease state within the spectrum of SLE.

Anti–IFN-γ autoantibodies in adults with disseminated nontuberculous mycobacterial infections are associated with HLA-DRB1*16:02 and HLA-DQB1*05:02 and the reactivation of latent varicella-zoster virus infection

Anti–IFN-γ autoantibodies are associated with HLA-DRB1*16:02 and DQB1*05:02.

Immunoregulation by naturally occurring and disease-associated autoantibodies : binding to cytokines and their role in regulation of T-cell responses

The role of naturally occurring autoantibodies (NAbs) in homeostasis and in disease manifestations is poorly understood. In the present chapter, we review how NAbs may interfere with the cytokine network and how NAbs, through formation of complement-activating immune complexes with soluble self-antigens, may promote the uptake and presentation of self-molecules by antigen-presenting cells. Both naturally occurring and disease-associated autoantibodies against a variety of cytokines have been reported, including NAbs against interleukin (IL)-1α, IL-6, IL-8, IL-10, granulocyte-macrophage colony-stimulating factor, interferon (IFN)-α, IFN-β, IFN-γ, macrophage chemotactic protein-1 and IL-21. NAbs against a variety of other self-antigens have also been reported, and using thyroglobulin as an example we discuss how NAbs are capable of promoting uptake of immune complexes via complement receptors and Fc-receptors on antigen-presenting cells and thereby regulate T-cell activity. Knowledge of the influence of NAbs against cytokines on immune homeostasis is likely to have wide-ranging implications both in understanding pathogenesis and in treatment of many immunoinflammatory disorders, including a number of autoimmune and autoinflammatory diseases.

Management of autoimmune neutropenia in Felty's syndrome and systemic lupus erythematosus

Autoimmune neutropenia, caused by neutrophil-specific autoantibodies is a common phenomenon in autoimmune disorders such as Felty's syndrome and systemic lupus erythematosus. Felty's syndrome is associated with neutropenia and splenomegaly in seropositive rheumatoid arthritis which can be severe and with recurrent bacterial infections. Neutropenia is also common in systemic lupus erythematosus and it is included in the current systemic lupus classification criteria. The pathobiology of the autoimmune neutropenia in Felty's syndrome and systemic lupus erythematosus is complex, and it could be a major cause of morbidity and mortality due to increased risk of sepsis. Treatment should be individualized on the basis of patient's clinical situation, and prevention or treatment of the infection. Recombinant human granulocyte colony-stimulating factor is a safe and effective therapeutic modality in management of autoimmune neutropenia associated with Felty's syndrome and systemic lupus erythematosus, which stimulates neutrophil production. There is a slight increased risk of exacerbation of the underlying autoimmune disorder, and recombinant human granulocyte colony-stimulating factor dose and frequency should be adjusted at the lowest effective dose.

Anticytokine autoantibodies in infectious diseases: pathogenesis and mechanisms

Autoantibodies to cytokines occur in many different conditions and situations and can cause a wide range of disease, including pulmonary alveolar proteinosis, disseminated non-tuberculous mycobacterial disease, pure red-cell aplasia, and chronic mucocutaneous candidiasis. Anticytokine autoantibodies may also develop against exogenously administered cytokines, sometimes diminishing their effects or inhibiting the activity of the endogenous cytokine. Unlike primary congenital immunodeficiencies, autoantibodies may develop over time, wax and wane, and may change in titre or avidity. Naturally occurring autoantibodies to interferons α, β, and γ, interleukins 1α, 2, 6, and 10, tumour necrosis factor, and granulocyte-macrophage colony-stimulating factor have been reported in healthy individuals and have been identified in rheumatological diseases, graft-versus-host disease, and cancer. Therapeutic antibodies, growth factors, other biological agents, and cytokines used to treat acute, chronic, malignant, and immune diseases may elicit or overcome autoantibodies, hence influencing the primary intended therapy. The increasing number of biologically active anticytokine autoantibodies being reported suggests that currently "idiopathic" diseases may someday be explained by neutralising or agonising autoantibodies. Their protean roles in causing, treating, preventing, and responding to disease, as well as simply maintaining normal homoeostasis, offer fascinating insights into the biology of immunity, inflammation, and infection.

Immunodeficiency secondary to anticytokine autoantibodies

PURPOSE OF REVIEW

Anticytokine autoantibodies are an important and emerging mechanism of disease pathogenesis. We will review the clinical and laboratory features of syndromes in which immunodeficiency is caused by or associated with neutralizing anticytokine autoantibodies.

RECENT FINDINGS

A growing number of patients have been described who demonstrate unique infectious phenotypes associated with neutralizing autoantibodies that target a particular cytokine known to participate in host defense against the offending organism. Examples include antigranulocyte macrophage-colony stimulating factor (GM-CSF) autoantibodies and pulmonary alveolar proteinosis; anti-interferon (IFN)-γ autoantibodies and disseminated nontuberculous mycobacteria (NTM); anti-interleukin-(IL)-6 autoantibodies and severe staphylococcal skin infection; anti-IL-17A, anti-IL-17F, or anti-IL-22 autoantibodies in patients with mucocutaneous candidiasis in the setting of both the autoimmune polyendocrinopathy, candidiasis, ectodermal dystrophy (APECED) syndrome and in cases of thymoma.

SUMMARY

Anticytokine autoantibodies have manifestations that are diverse, ranging from asymptomatic to life-threatening. These emerging and fascinating causes of acquired immunodeficiency may explain some previously idiopathic syndromes.