Naturally occurring anti-IFN-gamma autoantibody and severe infections with Mycobacterium cheloneae and Burkholderia cocovenenans

Clinical immunological characteristics of anti-interferon-γ autoantibodies syndrome: a 3 year prospective cohort study

Anti-interferon-γ autoantibodies (AIGAs) syndrome is susceptible to disseminated opportunistic infections due to increased AIGAs, but its clinical immunological characteristics remain unrecognized. We conducted a prospective cohort study between January 2021 and December 2023, recruiting patients with opportunistic infections who were categorized into AIGAs-positive and AIGAs-negative groups. Clinical immunological data and outcomes were documented. A subset of AIGAs-positive patients received glucocorticoid treatment, and its effectiveness was evaluated. A total of 238 patients were enrolled, with 135 AIGAs-positive and 103 AIGAs-negative patients. AIGAs-positive patients showed higher rates of multiple pathogen dissemination, shorter progression-free survival (PFS), and increased exacerbation frequency. They also showed elevated erythrocyte sedimentation rate (ESR), globulin (GLB), immunoglobulin (Ig)G, IgE, and IgG4 levels. Among the 70 AIGAs-positive patients monitored for at least six months, three subtypes were identified: high AIGAs titer with immune damage, high AIGAs titer without immune damage, and low AIGAs titer without immune damage. Of the 55 patients followed for 1 year, decreasing AIGAs titer and immune indices (GLB, IgG, IgE, IgG4) were observed. Among the 31 patients with high AIGAs titer and immune damage treated with low-dose glucocorticoids at the stable phase, reductions were observed in immune indices and AIGAs titer in 67.74% of cases. In summary, AIGAs-positive patients exhibit infectious and immunological characteristics. Elevated AIGAs, IgG, IgG4, and IgE indicate abnormal immune damages. AIGAs titer generally decrease over time. Stable-phase AIGAs-positive patients can be categorized into three subtypes, with those having high AIGAs titer and increased immune indices potentially benefitting from glucocorticoid treatment.

A patient with positive anti-IFN-γ autoantibody and monoclonal gammaglobulinemia masquerading as multiple myeloma: Case report and literature review

Key Clinical Message

Adult-onset immunodeficiency (AOID) is an emerging acquired immunodeficiency, characterized by multiple opportunistic infections including non-tuberculous mycobacterium (NTM) due to the presence of anti-IFN-γ autoantibody (AIGA). This case highlights the challenges of accurate diagnosis of monoclonal gammaglobulinemia with NTM infection and favorable outcomes of anti-plasma cell therapy in AOID.

Abstract

Adult-onset immunodeficiency (AOID) is an emerging acquired immunodeficiency due to anti-IFN-γ autoantibody (AIGA) with low morbidity, frequent disseminated infections, a prolonged course, difficult diagnosis and treatment, and a poor prognosis. Here, we report a patient with positive AIGA and monoclonal gammaglobulinemia who was mimicking symptomatic multiple myeloma and resulting in a non-tuberculous mycobacterial (NTM) infection. While he achieved an excellent therapeutic effect with anti-plasma cell therapy, it also serves as a warning that monoclonal gammaglobulinemia with NTM infection is easily misdiagnosed as symptomatic multiple myeloma, and the screening for AIGA should not be ignored in patients with NTM infection.

Disseminated Non-tuberculous Mycobacteriosis with a Skull Lesion Controlled by Resection after Exacerbation during Antimicrobial Chemotherapy in a Patient Positive for Anti-IFN-γ-neutralizing Autoantibodies

A 48-year-old man presented with a fever and back pain and was referred to our hospital with multiple bone destruction and abscess formation. A sputum examination revealed Mycobacterium intracellulare, and pathological findings revealed an indistinct granuloma and acid-fast bacilli, leading to a diagnosis of disseminated nontuberculous mycobacteriosis. Anti-interferon-γ-neutralizing autoantibodies were detected in the serum, and acquired immunodeficiency was suspected to be the etiology. Antimicrobial chemotherapy was initiated, and the lesions generally regressed. However, only the skull lesions worsened, requiring local resection to control the disease. Currently, the patient is continuing to receive drug therapy with good disease control after debridement.

Growing from common ground: nontuberculous mycobacteria and bronchiectasis

Bronchiectasis and nontuberculous mycobacteria (NTM) are intricately intertwined, with NTM capable of being both a cause and consequence of bronchiectatic disease. This narrative review focuses on the common ground of bronchiectasis and NTM pulmonary disease (NTM-PD) in terms of diagnostic approach, underlying risk factors and treatment strategies. NTM-PD diagnosis relies on a combination of clinical, radiological and microbiological criteria. Although their epidemiology is complicated by detection and reporting biases, the prevalence and pathogenicity of NTM species vary geographically, with Mycobacterium avium complex and Mycobacterium abscessus subspecies most frequently isolated in bronchiectasis-associated NTM-PD. Diagnosis of nodular bronchiectatic NTM-PD should prompt investigation of host factors, including disorders of mucociliary clearance, connective tissue diseases and immunodeficiencies, either genetic or acquired. Treatment of NTM-PD in bronchiectasis involves a multidisciplinary approach and considers the (sub)species involved, disease severity and comorbidities. Current guideline-based antimicrobial treatment of NTM-PD is considered long, cumbersome and unsatisfying in terms of outcomes. Novel treatment regimens and strategies are being explored, including rifampicin-free regimens and inclusion of clofazimine and inhaled antibiotics. Host-directed therapies, such as immunomodulators and cytokine-based therapies, might enhance antimycobacterial immune responses. Optimising supportive care, as well as pathogen- and host-directed strategies, is crucial, highlighting the need for personalised approaches tailored to individual patient needs. Further research is warranted to elucidate the complex interplay between host and mycobacterial factors, informing more effective management strategies.

The ouroboros of autoimmunity

Human autoimmunity against elements conferring protective immunity can be symbolized by the 'ouroboros', a snake eating its own tail. Underlying infection is autoimmunity against three immunological targets: neutrophils, complement and cytokines. Autoantibodies against neutrophils can cause peripheral neutropenia underlying mild pyogenic bacterial infections. The pathogenic contribution of autoantibodies against molecules of the complement system is often unclear, but autoantibodies specific for C3 convertase can enhance its activity, lowering complement levels and underlying severe bacterial infections. Autoantibodies neutralizing granulocyte-macrophage colony-stimulating factor impair alveolar macrophages, thereby underlying pulmonary proteinosis and airborne infections, type I interferon viral diseases, type II interferon intra-macrophagic infections, interleukin-6 pyogenic bacterial diseases and interleukin-17A/F mucocutaneous candidiasis. Each of these five cytokine autoantibodies underlies a specific range of infectious diseases, phenocopying infections that occur in patients with the corresponding inborn errors. In this Review, we analyze this ouroboros of immunity against immunity and posit that it should be considered as a factor in patients with unexplained infection.

Interferon- and infectious diseases: Lessons and prospects

Infectious diseases continue to claim many lives. Prevention of morbidity and mortality from these diseases would benefit not just from new medicines and vaccines but also from a better understanding of what constitutes protective immunity. Among the major immune signals that mobilize host defense against infection is interferon-γ (IFN-γ), a protein secreted by lymphocytes. Forty years ago, IFN-γ was identified as a macrophage-activating factor, and, in recent years, there has been a resurgent interest in IFN-γ biology and its role in human defense. Here we assess the current understanding of IFN-γ, revisit its designation as an "interferon," and weigh its prospects as a therapeutic against globally pervasive microbial pathogens.

Nasal Septal Perforation and Widespread Skin Lesions Caused by Mycobacterium chelonae Infection Mimicking Granulomatosis with Polyangiitis

Mycobacterium chelonae, a rapidly growing mycobacterium found in the natural environment, is known to cause localized lesions in the skin, soft tissue, and bone through traumatic inoculation, but widespread lesions are uncommon. We herein report an immunocompromised 79-year-old man suspected of having polyangiitis granulomatosis due to weight loss, epistaxis, and nasal crusts with impending septal perforation who was subsequently diagnosed with mucocutaneous and bone disease caused by widespread M. chelonae infection. Given these findings, clinicians should be aware of the tendency to develop unusual widespread lesions in immunocompromised patients, which can present a clinical picture similar to systemic vasculitides, such as granulomatosis with polyangiitis.

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.

Human autoantibodies neutralizing type I IFNs: From 1981 to 2023

Human autoantibodies (auto-Abs) neutralizing type I IFNs were first discovered in a woman with disseminated shingles and were described by Ion Gresser from 1981 to 1984. They have since been found in patients with diverse conditions and are even used as a diagnostic criterion in patients with autoimmune polyendocrinopathy syndrome type 1 (APS-1). However, their apparent lack of association with viral diseases, including shingles, led to wide acceptance of the conclusion that they had no pathological consequences. This perception began to change in 2020, when they were found to underlie about 15% of cases of critical COVID-19 pneumonia. They have since been shown to underlie other severe viral diseases, including 5%, 20%, and 40% of cases of critical influenza pneumonia, critical MERS pneumonia, and West Nile virus encephalitis, respectively. They also seem to be associated with shingles in various settings. These auto-Abs are present in all age groups of the general population, but their frequency increases with age to reach at least 5% in the elderly. We estimate that at least 100 million people worldwide carry auto-Abs neutralizing type I IFNs. Here, we briefly review the history of the study of these auto-Abs, focusing particularly on their known causes and consequences.

Neutralizing anti-IFN-γ IgG was increased in patients with systemic lupus erythematosus and associated with susceptibility to infection

OBJECTIVES

Systemic lupus erythematosus (SLE) is a complicated autoimmune disease, in which infection is a leading cause of death. Some SLE patients clinically presented with recurrent and refractory infections, which manifested as adult-onset immunodeficiency syndrome due to the production of anti-interferon-γ (anti-IFN-γ) autoantibodies. This study aimed to investigate the role of anti-IFN-γ autoantibodies concerning severe infections in SLE patients.

METHODS

We detected serum levels of anti-IFN-γ IgG/IgM isotypes in SLE patients with severe infections (n = 55), SLE patients without severe infections (n = 120), rheumatoid arthritis (n = 24), ankylosing spondylitis (n = 24), and healthy controls (n = 60). The relationship between anti-IFN-γ autoantibodies and clinical characteristics and laboratory parameters were analyzed. We further evaluated the neutralizing ability of anti-IFN-γ IgG.

RESULTS

The level of anti-IFN-γ IgG was significantly elevated in SLE patients with severe infections compared with the other groups (all p < 0.01), and the positive rates of anti-IFN-γ IgG in SLE patients with and without severe infections were 29.1% and 10.8%, respectively. Further analysis indicated that the levels of anti-IFN-γ IgG were positively associated with the SLEDAI score (r = 0.6420, p < 0.001), and it could predict the susceptibility to severe infections in SLE patients. Moreover, the inhibition and function assay showed that purified IgG from anti-IFN-γ IgG-positive SLE patients could neutralize IFN-γ, and further impair IFN-γ-induced STAT1 phosphorylation.

CONCLUSIONS

The neutralizing anti-IFN-γ IgG might increase the susceptibility to infection in SLE patients, which has important implications for the treatment. Key Points • The role of anti-IFN-γ autoantibodies concerning severe infections in SLE patients remains unknown. • The results of this study reveals that anti-IFN-γ IgG levels were significantly elevated in SLE patients with severe infections. • This study suggests that neutralizing anti-IFN-γ IgG might increase the susceptibility to infection in SLE patients.

Anticytokine Autoantibodies in Infectious Diseases: A Practical Overview

Anticytokine autoantibodies (ACAAs) are a fascinating group of antibodies that have gained more and more attention in the field of autoimmunity and secondary immunodeficiencies over the years. Some of these antibodies are characterized by their ability to target and neutralize specific cytokines. ACAAs can play a role in the susceptibility to several infectious diseases, and their infectious manifestations depending on which specific immunological pathway is affected. In this review, we will give an outline per infection in which ACAAs might play a role and whether additional immunomodulatory treatment next to antimicrobial treatment can be considered. Finally, we describe the areas for future research on ACAAs.

CXCL9 as a Reliable Biomarker for Discriminating Anti-IFN-γ-Autoantibody-Associated Lymphadenopathy that Mimics Lymphoma

The diagnosis of adult-onset immunodeficiency syndrome associated with neutralizing anti-interferon γ autoantibodies (AIGA) presents substantial challenges to clinicians and pathologists due to its nonspecific clinical presentation, absence of routine laboratory tests, and resemblance to certain lymphoma types, notably nodal T follicular helper cell lymphoma, angioimmunoblastic type (nTFHL-AI). Some patients undergo lymphadenectomy for histopathological examination to rule out lymphoma, even in the absence of a preceding clinical suspicion of AIGA. This study aimed to identify reliable methods to prevent misdiagnosis of AIGA in this scenario through a retrospective case-control analysis of clinical and pathological data, along with immune gene transcriptomes using the NanoString nCounter platform, to compare AIGA and nTFHL-AI. The investigation revealed a downregulation of the C-X-C motif chemokine ligand 9 (CXCL9) gene in AIGA, prompting an exploration of its diagnostic utility. Immunohistochemistry (IHC) targeting CXCL9 was performed on lymph node specimens to assess its potential as a diagnostic biomarker. The findings exhibited a significantly lower density of CXCL9-positive cells in AIGA compared to nTFHL-AI, displaying a high diagnostic accuracy of 92.3% sensitivity and 100% specificity. Furthermore, CXCL9 IHC demonstrated its ability to differentiate AIGA from various lymphomas sharing similar characteristics. In conclusion, CXCL9 IHC emerges as a robust biomarker for differentiating AIGA from nTFHL-AI and other similar conditions. This reliable diagnostic approach holds the potential to avert misdiagnosis of AIGA as lymphoma, providing timely and accurate diagnosis.

Disseminated Nontuberculous Mycobacterial Infection in a Tertiary Referral Hospital in South Korea: A Retrospective Observational Study

PURPOSE

Disseminated nontuberculous mycobacterial (D-NTM) disease occurs primarily in immunocompromised hosts. However, these cases have rarely been reported in South Korea. This study aimed to describe the clinical manifestations, disease course, and underlying immune deficiencies of patients with D-NTM disease.

MATERIALS AND METHODS

We retrospectively reviewed the cases of D-NTM disease from January 2005 to December 2019 at a tertiary referral hospital in South Korea. D-NTM disease was defined as a bloodstream infection or infection of two or more non-contiguous body organs with species identification.

RESULTS

Of the 53342 mycobacterial samples from 23338 patients, extrapulmonary NTM was detected in 104 patients, and 3 (2.9%) were diagnosed with D-NTM disease. Mycobacterium avium was isolated from two patients, while M. abscessus subspecies abscessus was identified in one. The patients were aged between 18 and 25 years, and two patients were male. All patients were immunocompromised - one received lung transplantation, one was diagnosed with anhidrotic ectodermal dysplasia with T-cell immune deficiency, and one had monocytopenia and mycobacterial infection syndrome associated with GATA2 mutations. All patients underwent a standard macrolide-based regimen for >5 months, and their sputum tested negative. However, one patient died of bacterial sepsis, while the other two survived.

CONCLUSION

D-NTM disease is rare in a tertiary referral center in South Korea. They occur primarily in immunocompromised patients at a relatively young age. Careful investigation of the underlying immune status is required when treating patients with D-NTM disease.

Characteristics and Outcomes of Anti-interferon Gamma Antibody-Associated Adult Onset Immunodeficiency

PURPOSE

Anti-interferon gamma antibody (AIGA) is a rare cause of adult onset immunodeficiency, leading to severe disseminated opportunistic infections with varying outcomes. We aimed to summarize the disease characteristics and to explore factors associated with disease outcome.

METHODS

A systematic literature review of AIGA associated disease was conducted. Serum-positive cases with detailed clinical presentations, treatment protocols, and outcomes were included. The patients were categorized into controlled and uncontrolled groups based on their documented clinical outcome. Factors associated with disease outcome were analyzed with logistic regression models.

RESULTS

A total of 195 AIGA patients were retrospectively analyzed, with 119(61.0%) having controlled disease and 76 (39.0%) having uncontrolled disease. The median time to diagnosis and disease course were 12 months and 28 months, respectively. A total of 358 pathogens have been reported with nontubercular mycobacterium (NTM) and Talaromyces marneffei as the most common pathogens. The recurrence rate was as high as 56.0%. The effective rates of antibiotics alone, antibiotics with rituximab, and antibiotics with cyclophosphamide were 40.5%, 73.5%, and 75%, respectively. In the multivariate logistic analysis, skin involvement, NTM infection, and recurrent infections remained significantly associated with disease control, with ORs of 3.25 (95% CI 1.187 ~ 8.909, P value = 0.022), 4.74 (95% CI 1.300 ~ 17.30, P value = 0.018), and 0.22 (95% CI 0.086 ~ 0.551, P value = 0.001), respectively. The patients with disease control had significant AIGA titer reduction.

CONCLUSIONS

AIGA could cause severe opportunistic infections with unsatisfactory control, particularly in patients with recurrent infections. Efforts should be made to closely monitor the disease and regulate the immune system.

Tuberculosis and COVID-19 in the elderly: factors driving a higher burden of disease

Mycobacterium tuberculosis (M.tb) and SARS-CoV-2 are both infections that can lead to severe disease in the lower lung. However, these two infections are caused by very different pathogens (Mycobacterium vs. virus), they have different mechanisms of pathogenesis and immune response, and differ in how long the infection lasts. Despite the differences, SARS-CoV-2 and M.tb share a common feature, which is also frequently observed in other respiratory infections: the burden of disease in the elderly is greater. Here, we discuss possible reasons for the higher burden in older adults, including the effect of co-morbidities, deterioration of the lung environment, auto-immunity, and a reduced antibody response. While the answer is likely to be multifactorial, understanding the main drivers across different infections may allow us to design broader interventions that increase the health-span of older people.

Examination of autoantibodies to type I interferon in patients suffering from long COVID

Long COVID (LC) is an emerging global health concern. The underlying mechanism and pathophysiology remain unclear. Presence of neutralizing autoantibodies against type 1 interferons (IFN) has been established as a predictor of critical COVID-19. We hypothesized that persistent autoimmune activity with autoantibodies against type 1 IFN may contribute to symptoms in patients with LC. Plasma samples and clinical information were obtained from a Danish LC cohort consisting of adult patients with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Information on symptoms and quality of life was derived from an LC-specific questionnaire and the EQ-5D-5L questionnaire. Detection of type 1 IFN autoantibodies in plasma were performed by ELISA. Samples collected between June, 2020, and September, 2021, from 279 patients were analyzed and compared to a control group of 94 individuals with prior mild SARS-CoV-2 infection who did not develop LC symptoms. In total, five LC patients (1.8%) and 3 (3.2%) of the controls had detectable circulating type 1 IFN autoantibodies. Collectively, prevalence of autoantibodies against type 1 IFN subtypes in our LC cohort were primarily driven by men and did not exceed the prevalence in controls. Thus, in our cohort, anti-type I IFN autoantibodies are unlikely to drive LC symptoms.

Case report: Diagnosis of Talaromyces marneffei infection in an HIV-negative patient with septic shock and high-titer anti-interferon gamma autoantibodies by metagenomic next-generation sequencing

Background

Sepsis is a life-threatening condition caused by a dysfunctional response to infection from the host. Septic shock, a subset of sepsis, caused by Talaromyces marneffei infection (talaromycosis) has rarely been reported. Owing to its slow culture and low yield, talaromycosis is typically misdiagnosed in HIV-negative patients as other infections, such as tuberculosis, bacterial pneumonia, and lung cancer, especially in non-endemic regions. Early and accurate diagnosis as well as efficient treatment options are required to improve prognosis.

Method

A 30-year-old HIV-negative Chinese woman from a non-endemic area of T. marneffei was initially misdiagnosed with tuberculosis. She had a poor response to anti-tuberculosis treatment. On July 16, 2022, she was admitted to our hospital; the patient developed septic shock on the third day after hospitalization and was ultimately diagnosed with talaromycosis via metagenomic next-generation sequencing (mNGS).

Result

The condition of the patient improved after appropriate treatment with amphotericin B. Furthermore, enzyme-linked immunosorbent assay results confirmed that the patient had a high-titer of anti-interferon gamma (IFN-γ) autoantibodies.

Conclusion

HIV-negative individuals with anti-IFN-γ autoantibodies typically have relapsing, refractory, and fatal infections, such as talaromycosis, which is typically misdiagnosed in the initial course of the disease. This can lead to septic shock. Clinicians should be aware that they may encounter HIV-negative patients with T. marneffei infection in non-endemic areas. Thus, mNGS is an effective technology for detecting T. marneffei infection. Additionally, the detection of anti-IFN-γ autoantibodies in these patients would aid in knowing their susceptibility to fatal infections.

From second thoughts on the germ theory to a full-blown host theory

In 1955, René Dubos famously expressed his "second thoughts on the germ theory", attributing infectious diseases to various "changing circumstances" that weaken the host by unknown mechanisms. He rightly stressed that only a small minority of individuals infected by almost any microbe develop clinical disease. Intriguingly, though, he did not mention the abundant and elegant findings reported from 1905 onward that unambiguously pointed to host genetic determinants of infection outcome in plants and animals, including human inborn errors of immunity. Diverse findings over the next 50 y corroborated and extended these earlier genetic and immunological observations that René Dubos had neglected. Meanwhile, the sequential advent of immunosuppression- and HIV-driven immunodeficiencies unexpectedly provided a mechanistic basis for his own views. Collectively, these two lines of evidence support a host theory of infectious diseases, with inherited and acquired immunodeficiencies as the key determinants of severe infection outcome, relegating the germ to an environmental trigger that reveals an underlying and preexisting cause of disease and death.

Autoantibodies to Interferons in Infectious Diseases

Anti-cytokine autoantibodies and, in particular, anti-type I interferons are increasingly described in association with immunodeficient, autoimmune, and immune-dysregulated conditions. Their presence in otherwise healthy individuals may result in a phenotype characterized by a predisposition to infections with several agents. For instance, anti-type I interferon autoantibodies are implicated in Coronavirus Disease 19 (COVID-19) pathogenesis and found preferentially in patients with critical disease. However, autoantibodies were also described in the serum of patients with viral, bacterial, and fungal infections not associated with COVID-19. In this review, we provide an overview of anti-cytokine autoantibodies identified to date and their clinical associations; we also discuss whether they can act as enemies or friends, i.e., are capable of acting in a beneficial or harmful way, and if they may be linked to gender or immunosenescence. Understanding the mechanisms underlying the production of autoantibodies could improve the approach to treating some infections, focusing not only on pathogens, but also on the possibility of a low degree of autoimmunity in patients.

Interferon and autoantigens: intersection in autoimmunity

Interferon (IFN) is a key component of the innate immune response. For reasons that remain incompletely understood, the IFN system is upregulated in several rheumatic diseases, particularly those that feature autoantibody production, such as SLE, Sjögren's syndrome, myositis and systemic sclerosis. Interestingly, many of the autoantigens targeted in these diseases are components of the IFN system, representing IFN-stimulated genes (ISGs), pattern recognition receptors (PRRs), and modulators of the IFN response. In this review, we describe features of these IFN-linked proteins that may underlie their status as autoantigens. Note is also made of anti-IFN autoantibodies that have been described in immunodeficiency states.

Clinical Characteristics, Course, and Long-Term Outcomes in Patients with Talaromyces marneffei Infection: A 10-Year Retrospective Cohort Study

INTRODUCTION

Talaromyces marneffei (T. marneffei), a dimorphic fungus, causes local or disseminated infection in humans. We aimed to analyze the clinical characteristics, prognostic factors, and survival outcomes of patients with T. marneffei infection and compare the differences between human immunodeficiency virus (HIV)-positive and HIV-negative subgroups.

METHODS

We retrospectively analyzed 241 patients with T. marneffei infection at the First Affiliated Hospital of Guangxi Medical University between January 2012 and January 2022. The overall population was stratified into HIV-positive (n = 98) and HIV-negative (n = 143) groups according to HIV status. Kaplan-Meier analysis and multivariate Cox regression models were used to determine the prognostic factors for overall survival (OS) and progression-free survival (PFS).

RESULTS

With a median follow-up time of 58.9 months, 120 patients (49.8%) experienced disease progression and 85 patients (70.8%) died. The 5-year rates of OS and PFS were 61.4% (95% CI 55.0-68.6%) and 47.8% (95% CI 41.5-55.1%), respectively. As an independent factor, patients who were HIV positive had better PFS (HR 0.50, 95% CI 0.31-0.82; p < 0.01) than patients who were HIV negative. Compared with patients who were HIV positive, patients who were HIV negative were older and had more probabilities of underlying diseases, chest involvement, bone destruction, and higher count of neutrophils (all p < 0.05). Hemoglobin (PFS: HR 0.62; 95% CI 0.39-1.00; p < 0.05; OS: HR 0.45; 95% CI 0.22-0.89; p = 0.02) and lymphocyte count (PFS: HR 0.06; 95% CI 0.01-0.26; p < 0.01; OS: HR 0.08; 95% CI 0.01-0.40; p < 0.01) were independent prognostic factors for PFS and OS in patients who were HIV negative.

CONCLUSIONS

Patients with T. marneffei infection have a poor prognosis. Patients who are HIV positive and HIV negative have relatively independent clinical characteristics. Multiple organ involvement and disease progression are more common in patients who are HIV negative.

An Overlooked and Underrated Endemic Mycosis-Talaromycosis and the Pathogenic Fungus Talaromyces marneffei

Talaromycosis is an invasive mycosis endemic in tropical and subtropical Asia and is caused by the pathogenic fungus Talaromyces marneffei. Approximately 17,300 cases of T. marneffei infection are diagnosed annually, and the reported mortality rate is extremely high (~1/3). Despite the devastating impact of talaromycosis on immunocompromised individuals, particularly HIV-positive persons, and the increase in reported occurrences in HIV-uninfected persons, diagnostic and therapeutic approaches for talaromycosis have received far too little attention worldwide. In 2021, scientists living in countries where talaromycosis is endemic raised a global demand for it to be recognized as a neglected tropical disease. Therefore, T. marneffei and the infectious disease induced by this fungus must be treated with concern. T. marneffei is a thermally dimorphic saprophytic fungus with a complicated mycological growth process that may produce various cell types in its life cycle, including conidia, hyphae, and yeast, all of which are associated with its pathogenicity. However, understanding of the pathogenic mechanism of T. marneffei has been limited until recently. To achieve a holistic view of T. marneffei and talaromycosis, the current knowledge about talaromycosis and research breakthroughs regarding T. marneffei growth biology are discussed in this review, along with the interaction of the fungus with environmental stimuli and the host immune response to fungal infection. Importantly, the future research directions required for understanding this serious infection and its causative pathogenic fungus are also emphasized to identify solutions that will alleviate the suffering of susceptible individuals worldwide.

Of Mycelium and Men: Inherent Human Susceptibility to Fungal Diseases

In medical mycology, the main context of disease is iatrogenic-based disease. However, historically, and occasionally, even today, fungal diseases affect humans with no obvious risk factors, sometimes in a spectacular fashion. The field of “inborn errors of immunity” (IEI) has deduced at least some of these previously enigmatic cases; accordingly, the discovery of single-gene disorders with penetrant clinical effects and their immunologic dissection have provided a framework with which to understand some of the key pathways mediating human susceptibility to mycoses. By extension, they have also enabled the identification of naturally occurring auto-antibodies to cytokines that phenocopy such susceptibility. This review provides a comprehensive update of IEI and autoantibodies that inherently predispose humans to various fungal diseases.

Mycobacterial mycolic acids trigger inhibitory receptor Clec12A to suppress host immune responses

Mycobacteria often cause chronic infection. To establish persistence in the host, mycobacteria need to evade host immune responses. However, the molecular mechanisms underlying the evasion strategy are not fully understood. Here, we demonstrate that mycobacterial cell wall lipids trigger an inhibitory receptor to suppress host immune responses. Mycolic acids are major cell wall components and are essential for survival of mycobacteria. By screening inhibitory receptors that react with mycobacterial lipids, we found that mycolic acids from various mycobacterial species bind to mouse Clec12A, and more potently to human Clec12A. Clec12A is a conserved inhibitory C-type lectin receptor containing immunoreceptor tyrosine-based inhibitory motif (ITIM). Innate immune responses, such as MCP-1 production, and PPD-specific recall T cell responses were augmented in Clec12A-deficient mice after infection. In contrast, human Clec12A transgenic mice were susceptible to infection with M. tuberculosis. These results suggest that mycobacteria dampen host immune responses by hijacking an inhibitory host receptor through their specific and essential lipids, mycolic acids. The blockade of this interaction might provide a therapeutic option for the treatment or prevention of mycobacterial infection.

Epidural intracranial abscesses and multiple bone metastases caused by disseminated Mycobacterium avium complex infection: illustrative case

BACKGROUND

Mycobacterium avium complex (MAC) generally causes localized pulmonary infections in immunocompromised hosts, but rarely in other organs and tissues, which is called disseminated MAC infection.

OBSERVATIONS

The authors herein present a 48-year-old male patient with disseminated MAC infectious lesions in the lungs and on the cranial, vertebral, femoral, and pelvic bones, a normal CD4 count, and immunopositivity for the interferon-ɤ (IFN-ɤ) neutralization antibody. Cranial lesions were multiple osteolytic lesions associated with abscesses in the cranial bones. The patient initially received conservative treatment with multiple antibiotics; however, cranial lesions worsened. Therefore, multiple cranial lesions were removed via osteoplastic craniectomy and the postoperative course was uneventful. Pathological findings revealed MAC infection. The patient was discharged without recurrence or complications.

LESSONS

Multiple cranial MAC dissemination with immunopositivity for the IFN-ɤ antibody is rare. The authors herein present the clinical course of a rare surgical case of MAC dissemination with a literature review.

Case report: Drug rash with eosinophilia and systemic symptoms syndrome in a patient with anti–interferon-γ autoantibody–associated immunodeficiency

A 56-year-old Chinese woman with previous disseminated mycobacterium avium complex infection and recurrent cervical abscesses from Burkholderia cepacia complex visited our hospital. She was diagnosed with adult-onset immunodeficiency (AOID) and tested positive for interferon-γ–neutralizing autoantibody. Ceftazidime was administered as the initial antimicrobial treatment, which was later combined with sulfamethoxazole-trimethoprim (SMZ-TMP). She developed drug rash with eosinophilia and systemic symptoms (DRESS) syndrome after SMZ-TMP administration and improved after withdrawal of the culprit antibiotic and systemic glucocorticoids treatment. Her cervical infection was eventually cured after combined therapy of long-term antibiotics and anti–IFN-γ autoantibodies (AIGA) titer-lowering treatments including glucocorticoids, rituximab, and plasmapheresis. This is the first case of DRESS syndrome in the setting of AIGA-induced AOID and is worthy of notice.

Pathogenic autoantibodies to IFN-γ act through the impedance of receptor assembly and Fc-mediated response

Anti-interferon (IFN)-γ autoantibodies (AIGAs) are a pathogenic factor in late-onset immunodeficiency with disseminated mycobacterial and other opportunistic infections. AIGAs block IFN-γ function, but their effects on IFN-γ signaling are unknown. Using a single-cell capture method, we isolated 19 IFN-γ-reactive monoclonal antibodies (mAbs) from patients with AIGAs. All displayed high-affinity (KD < 10-9 M) binding to IFN-γ, but only eight neutralized IFN-γ-STAT1 signaling and HLA-DR expression. Signal blockade and binding affinity were correlated and attributed to somatic hypermutations. Cross-competition assays identified three nonoverlapping binding sites (I-III) for AIGAs on IFN-γ. We found that site I mAb neutralized IFN-γ by blocking its binding to IFN-γR1. Site II and III mAbs bound the receptor-bound IFN-γ on the cell surface, abolishing IFN-γR1-IFN-γR2 heterodimerization and preventing downstream signaling. Site III mAbs mediated antibody-dependent cellular cytotoxicity, probably through antibody-IFN-γ complexes on cells. Pathogenic AIGAs underlie mycobacterial infections by the dual blockade of IFN-γ signaling and by eliminating IFN-γ-responsive cells.

Anti-cytokine autoantibodies and inborn errors of immunity

The past quarter of a century has witnessed an inordinate increase in our understanding of primary immunodeficiencies / inborn errors of immunity. These include a significant increase in the number of identified conditions, broadening the phenotypes of existing entities, delineation of classical inborn errors of immunity from those with a narrow phenotype, and a gradual shift from supportive to definitive care in patients afflicted with these diseases. It has also seen the discovery of conditions broadly defined as phenocopies of primary immunodeficiencies, where somatic mutations or autoantibodies mimic a recognised primary immunodeficiency's presentation in the absence of the underlying genetic basis for that disease. This article will provide a review of the anti-cytokine autoantibody-mediated phenocopies of inborn errors of immunity and discuss the therapeutic and laboratory aspects of this group of diseases.

Periocular Infection of Mycobacterium avium Complex in a Patient with Interferon-γ Autoantibodies: A Case Report

The neutralizing anti-interferon-γ autoantibody (nAIGA)-associated immunodeficiency is an emerging entity frequently associated with the nontuberculosis mycobacterium (NTM) infection and other opportunistic infections. We present a female patient with a mysterious periocular Mycobacterium avium complex (MAC) infection, accompanied by sequential opportunistic infections including Salmollelosis and herpes zoster infection. Her condition stabilized after long-term antimycobacterial treatment. Nevertheless, neutralizing anti-interferon-γ autoantibody was found in her serum, which was compatible with the scenario of adult-onset immunodeficiency.

Disseminated Mycolicibacter arupensis and Mycobacterium avium co-infection in a patient with anti-interferon-γ neutralizing autoantibody-associated immunodeficiency syndrome

BACKGROUND

Disseminated infections of Mycolicibacter arupensis, a slowly growing nontuberculous mycobacteria (NTM) which causes synovitis, osteomyelitis, or pulmonary infections have rarely been reported. We report a case of disseminated M. arupensis and Mycobacterium avium co-infection in a patient with anti-interferon (IFN)-γ neutralizing autoantibody-associated immunodeficiency syndrome.

CASE PRESENTATION

A 68-year-old Japanese male without human immunodeficiency virus infection was referred with complaints of persistent low-grade fever, arthralgia of the upper limbs, and weight loss of 10 kg. Cervical and mediastinal lymphadenopathies as well as a nodular opacity in the right lung were detected, and biopsy specimens of the cervical lymph node yielded M. arupensis without evidence of malignant cells. M. arupensis was also detected in sputum and peripheral blood. Computed tomography (CT) revealed deterioration of the right supraclavicular lymphadenopathy with internal necrosis and multiple low-density splenic lesions. Bone marrow and aspirates from the cervical lymph node collected at initiation of treatment yielded M. avium. The presence of anti-IFN-γ neutralizing autoantibodies was detected, leading to a diagnosis of co-infection of M. arupensis and M. avium with anti-IFN-γ neutralizing autoantibody-associated immunodeficiency syndrome. Post initiation of treatment with clarithromycin, ethambutol, and rifabutin, his fever declined, and his polyarthritis resolved. He developed disseminated varicella zoster during treatment; however, a follow-up CT scan six months after treatment revealed improvement of the lymphadenopathies, consolidation in the right lung, and splenic lesions.

CONCLUSION

This is the first report of disseminated M. arupensis and M. avium co-infection in a patient with anti-IFN-γ neutralizing autoantibody-associated immunodeficiency syndrome.

Gut microbiome profiles and associated metabolic pathways in patients of adult-onset immunodeficiency with anti-interferon-gamma autoantibodies

Autoantibodies against interferon-gamma (AutoAbs-IFN-γ) can cause the immunodeficiency condition following various opportunistic infections. Gut microbiota can affect the human immune system in many ways. Many studies have shown that gut dysbiosis was associated with some immune diseases, such as autoimmune diseases and human immunodeficiency virus (HIV) infection, while its relationship at anti-IFN-γ AAbs remains unknown. We aimed to identify the anti-IFN-γ AAbs specific microbiome and the possible association with immunodeficiency. We profiled fecal microbiome for two cohorts of forty subjects, including seven patients with anti-IFN-γ AAbs and 33 individuals with competent immune. The study shows that patients with anti-IFN-γ AAbs have characterized the gut microbiome and have lower alpha diversity indexes than healthy controls (HC). There are significant differences in the microbiome structure at both the family and genera level between the two cohorts. The anti-IFN-γ AAbs cohort featured some microbiome such as Clostridium, including the possible opportunistic pathogen and fewer genera including Bacteroides, Ruminococcus, and Faecalibacterium, some of them with possible immune-related genera. The PICRUSt2 pathway demonstrated the decreased abundance of some immune-related pathways and one potential pathway related to the immune alternations in the anti- IFN-γ AAbs cohort. This was the first study to examine the gut microbiome characteristics in patients with anti-IFN-γ AAbs. It could be involved in the pathogenesis of anti-IFN-γ AAbs and contribute to the derived immune condition in this disease. This could lead to new strategies for treating and preventing patients suffering from this disease.

The risk of COVID-19 death is much greater and age dependent with type I IFN autoantibodies

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection fatality rate (IFR) doubles with every 5 y of age from childhood onward. Circulating autoantibodies neutralizing IFN-α, IFN-ω, and/or IFN-β are found in ∼20% of deceased patients across age groups, and in ∼1% of individuals aged <70 y and in >4% of those >70 y old in the general population. With a sample of 1,261 unvaccinated deceased patients and 34,159 individuals of the general population sampled before the pandemic, we estimated both IFR and relative risk of death (RRD) across age groups for individuals carrying autoantibodies neutralizing type I IFNs, relative to noncarriers. The RRD associated with any combination of autoantibodies was higher in subjects under 70 y old. For autoantibodies neutralizing IFN-α2 or IFN-ω, the RRDs were 17.0 (95% CI: 11.7 to 24.7) and 5.8 (4.5 to 7.4) for individuals <70 y and ≥70 y old, respectively, whereas, for autoantibodies neutralizing both molecules, the RRDs were 188.3 (44.8 to 774.4) and 7.2 (5.0 to 10.3), respectively. In contrast, IFRs increased with age, ranging from 0.17% (0.12 to 0.31) for individuals <40 y old to 26.7% (20.3 to 35.2) for those ≥80 y old for autoantibodies neutralizing IFN-α2 or IFN-ω, and from 0.84% (0.31 to 8.28) to 40.5% (27.82 to 61.20) for autoantibodies neutralizing both. Autoantibodies against type I IFNs increase IFRs, and are associated with high RRDs, especially when neutralizing both IFN-α2 and IFN-ω. Remarkably, IFRs increase with age, whereas RRDs decrease with age. Autoimmunity to type I IFNs is a strong and common predictor of COVID-19 death.

Human autoantibodies underlying infectious diseases

The vast interindividual clinical variability observed in any microbial infection-ranging from silent infection to lethal disease-is increasingly being explained by human genetic and immunological determinants. Autoantibodies neutralizing specific cytokines underlie the same infectious diseases as inborn errors of the corresponding cytokine or response pathway. Autoantibodies against type I IFNs underlie COVID-19 pneumonia and adverse reactions to the live attenuated yellow fever virus vaccine. Autoantibodies against type II IFN underlie severe disease caused by environmental or tuberculous mycobacteria, and other intra-macrophagic microbes. Autoantibodies against IL-17A/F and IL-6 are less common and underlie mucocutaneous candidiasis and staphylococcal diseases, respectively. Inborn errors of and autoantibodies against GM-CSF underlie pulmonary alveolar proteinosis; associated infections are less well characterized. In individual patients, autoantibodies against cytokines preexist infection with the pathogen concerned and underlie the infectious disease. Human antibody-driven autoimmunity can interfere with cytokines that are essential for protective immunity to specific infectious agents but that are otherwise redundant, thereby underlying specific infectious diseases.

Human genetic and immunological determinants of critical COVID-19 pneumonia

SARS-CoV-2 infection is benign in most individuals but, in _˜10% of cases, it triggers hypoxemic COVID-19 pneumonia, which becomes critical in _˜3% of cases. The ensuing risk of death (_˜1%) doubles every five years from childhood onward and is _˜1.5 times greater in men than in women. What are the molecular and cellular determinants of critical COVID-19 pneumonia? Inborn errors of type I IFNs, including autosomal TLR3 and X-linked TLR7 deficiencies, are found in _˜1-5% of patients with critical pneumonia under 60 years old, and a lower proportion in older patients. Pre-existing autoantibodies neutralizing IFN-α, -β, and/or -ω, which are more common in men than in women, are found in _˜15-20% of patients with critical pneumonia over 70 years old, and a lower proportion in younger patients. Thus, at least 15% of cases of critical COVID-19 pneumonia can apparently be explained. The TLR3- and TLR7-dependent production of type I IFNs by respiratory epithelial cells and plasmacytoid dendritic cells, respectively, is essential for host defense against SARS-CoV-2. In ways that can depend on age and sex, insufficient type I IFN immunity in the respiratory tract during the first few days of infection may account for the spread of the virus, leading to pulmonary and systemic inflammation.

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 risk of COVID-19 death is much greater and age-dependent with type I IFN autoantibodies

SARS-CoV-2 infection fatality rate (IFR) doubles with every five years of age from childhood onward. Circulating autoantibodies neutralizing IFN-α, IFN-ω, and/or IFN-β are found in ~20% of deceased patients across age groups. In the general population, they are found in ~1% of individuals aged 20-70 years and in >4% of those >70 years old. With a sample of 1,261 deceased patients and 34,159 uninfected individuals, we estimated both IFR and relative risk of death (RRD) across age groups for individuals carrying autoantibodies neutralizing type I IFNs, relative to non-carriers. For autoantibodies neutralizing IFN-α2 or IFN-ω, the RRD was 17.0[95% CI:11.7-24.7] for individuals under 70 years old and 5.8[4.5-7.4] for individuals aged 70 and over, whereas, for autoantibodies neutralizing both molecules, the RRD was 188.3[44.8-774.4] and 7.2[5.0-10.3], respectively. IFRs increased with age, from 0.17%[0.12-0.31] for individuals <40 years old to 26.7%[20.3-35.2] for those ≥80 years old for autoantibodies neutralizing IFN-α2 or IFN-ω, and from 0.84%[0.31-8.28] to 40.5%[27.82-61.20] for the same two age groups, for autoantibodies neutralizing both molecules. Autoantibodies against type I IFNs increase IFRs, and are associated with high RRDs, particularly those neutralizing both IFN-α2 and -ω. Remarkably, IFR increases with age, whereas RRD decreases with age. Autoimmunity to type I IFNs appears to be second only to age among common predictors of COVID-19 death.

Anticytokine autoantibodies: Autoimmunity trespassing on antimicrobial immunity

Anticytokine autoantibodies can cause immunodeficiency or dysregulate immune responses. They may phenocopy genetically defined primary immunodeficiencies. We review current anti-type 1 and anti-type 2 interferon; anti-IL-12/23, anti-IL-17, and anti-GM-CSF autoantibodies; HLA associations; disease associations; and mechanistically based treatment options. Suspecting the presence of these autoantibodies in patients and identifying them at the onset of symptoms should ameliorate disease and improve outcomes.

Morphologic Spectrum of Lymphadenopathy in Adult-onset Immunodeficiency (Anti-interferon-γ Autoantibodies)

Adult-onset immunodeficiency syndrome (AOIS) caused by anti-interferon-γ autoantibodies is an emerging disease. Affected patients present typically with systemic lymphadenopathy, fatigue, and fever. We studied 36 biopsy specimens, 31 lymph nodes, and 5 extranodal sites, of AOIS confirmed by serum autoantibody or QuantiFERON-TB Gold In-Tube assay. We describe the morphologic features and the results of ancillary studies, including special stains, immunohistochemistry, and molecular testing. The overall median age of these patients was 60.5 years (range, 41 to 83 y) with a male-to-female ratio of 20:16. All biopsy specimens showed nontuberculous mycobacterial infection, and most cases showed the following histologic features: capsular thickening with intranodal sclerosing fibrosis, irregularly distributed ill-formed granulomas or histiocytic aggregates with neutrophilic infiltration, interfollicular expansion by a polymorphic infiltrate with some Hodgkin-like cells that commonly effaces most of the nodal architecture and proliferation of high endothelial venules. In situ hybridization analysis for Epstein-Barr virus-encoded RNA showed scattered (<1%) to relatively more common (4% to 5%) positive cells in 29 of 30 (97%) tested specimens, reflecting immune dysregulation due to an interferon-γ defect. In the 31 lymph node specimens, 23 (74%) cases showed increased immunoglobulin G4-positive plasma cells (4 to 145/HPF; mean, 49.7/HPF) with focal areas of sclerosis reminiscent of immunoglobulin G4-related lymphadenopathy, 4 (13%) cases resembled, in part, nodular sclerosis Hodgkin lymphoma, and 9 (29%) cases mimicked T-cell lymphoma. Among 33 patients with available clinical follow-up, 20 (61%) showed persistent or refractory disease despite antimycobacterial therapy, and 1 patient died of the disease. We conclude that the presence of ill-defined granulomas, clusters of neutrophils adjacent to the histiocytic aggregates, and some Epstein-Barr virus-positive cells are features highly suggestive of AOIS. A high index of clinical suspicion and awareness of the morphologic features and differential diagnosis of AOIS are helpful for establishing the diagnosis.

Disseminated Mycobacterium avium complex infection in a woman with anti-interferon-γ autoantibodies

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Disseminated MAC infections should always prompt investigations for immunodeficiencies.

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Anti-IFN-γ autoantibodies may lead to severe treatment refractory mycobacterial infection.

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Clinical studies investigating immunomodulating therapy of patients with anti-IFN-γ autoantibodies are lacking

Defects in the interleukin-12/interferon-gamma (IFN-γ) pathway and anti-IFN-γ antibodies have been associated with severe nontuberculous mycobacteria (NTM) infections. Consequently, disseminated NTM infections should prompt investigations for immunodeficiency. Herein, we report a case of a treatment refractory and ultimately disseminated and fatal Mycobacterium avium complex infection in a 71-year-old woman of Thai origin. Simultaneously, she had recurrent Salmonella kentucky cultured from stool samples and chronic perianal HSV-2 lesions. Late in the course of disease, anti–IFN-γ autoantibodies were demonstrated. Clinical studies investigating immunomodulating therapy and treatment among patients with anti-IFN-γ autoantibodies are lacking and, in this case, treatment seemed of a more palliative nature.

Application of QuantiFERON ELISA for Detection of Interferon-Gamma Autoantibodies in Adult-Onset Immunodeficiency Syndrome

OBJECTIVE

Patients who develop interferon-gamma autoantibodies (IFN-ɤ autoAbs) in adult-onset immunodeficiency (AOID) syndrome are more likely to develop opportunistic and recurrent intracellular infections. The assay to detect IFN-ɤ autoAbs is essential for the diagnosis and therapeutic monitoring of AOID syndrome. Therefore, this study applied the QuantiFERON assay for the detection of IFN-ɤ autoAbs.

METHODS

Serum from patients with AOID syndrome (n = 19) and serum from healthy patients (n = 20) was collected and applied using 2 neutralizing platforms of enzyme-linked immunosorbent assay (ELISA) kits (the BD ELISA and the QuantiFERON ELISA) for IFN-ɤ autoAbs detection.

RESULTS

The pooled serum from patients with AOID syndrome showed >50% inhibition at 1:5000 dilution (positive), whereas the pooled serum from healthy patients showed <50% inhibition at 1:5000 dilution (negative) according to the neutralizing QuantiFERON ELISA. Each specimen showed the same result according to both the neutralizing BD ELISA and the neutralizing QuantiFERON ELISA. Moreover, the patient serum showed a variation in titer ranging from 1:5000 to >1:5,000,000 according to the neutralizing QuantiFERON ELISA.

CONCLUSION

The QuantiFERON ELISA kit could be applied for the detection of IFN-ɤ autoAbs for the diagnosis and therapeutic monitoring of AOID syndrome.

Lymphadenopathy Associated With Neutralizing Anti-interferon-gamma Autoantibodies Could Have Monoclonal T-cell Proliferation Indistinguishable From Malignant Lymphoma and Treatable by Antibiotics: A Clinicopathologic Study

Early recognition of adult-onset immunodeficiency associated with neutralizing anti-interferon gamma autoantibodies (anti-IFNγ Abs) remains difficult, and misdiagnoses have been reported. Although febrile lymphadenopathy is among the most common initial manifestations of this disorder, no comprehensive clinicopathologic analysis of lymphadenopathy in patients with anti-IFNγ Abs has been reported. Here, we describe 26 lymph node biopsy specimens from 16 patients. All patients exhibited concurrent disseminated nontuberculous mycobacterial infections, and 31% received a tentative diagnosis of lymphoma at initial presentation. We found 3 distinct histomorphologic patterns: well-formed granuloma (46%), suppurative inflammation or loose histiocytic aggregates (31%), and lymphoproliferative disorder (LPD, 23%). The latter shared some of the features of malignant T-cell lymphoma, IgG4-related disease, and multicentric Castleman disease. Half of the specimens with LPD had monoclonal T cells, and 33.3% were indistinguishable from angioimmunoblastic T-cell lymphoma as per current diagnostic criteria. All lymphadenopathy with LPD features regressed with antibiotics without administration of cytotoxic chemotherapy or immunotherapy. The median follow-up time was 4.3 years. Our study highlights the substantial challenge of distinguishing between lymphoma and other benign lymphadenopathy in the setting of neutralizing anti-IFNγ Abs. Increased vigilance and multidisciplinary discussion among clinicians and pathologists are required to achieve the most appropriate diagnosis and management.

Mycobacterial diseases in patients with inborn errors of immunity

Clinical disease caused by the agent of tuberculosis, Mycobacterium tuberculosis, and by less virulent mycobacteria, such as bacillus Calmette-Guérin (BCG) vaccines and environmental mycobacteria, can result from inborn errors of immunity (IEIs). IEIs underlie more than 450 conditions, each associated with an impairment of the development and/or function of hematopoietic and/or non-hematopoietic cells involved in host defense. Only a minority of IEIs confer predisposition to mycobacterial disease. The IEIs underlying susceptibility to bona fide tuberculosis are less well delineated than those responsible for susceptibility to less virulent mycobacteria. However, all these IEIs share a defining feature: the impairment of immunity mediated by interferon gamma (IFN-γ). More profound IFN-γ deficiency is associated with a greater vulnerability to weakly virulent mycobacteria, whereas more selective IFN-γ deficiency is associated with a more selective predisposition to mycobacterial disease. We review here recent progress in the study of IEIs underlying mycobacterial diseases.

Anti-interferon-γ autoantibody-associated immunodeficiency

Anticytokine autoantibodies are an emerging disease etiology, through the disturbance of physiological functions of cognate cytokines. Anti-interferon (IFN)-γ autoantibodies (AIGAs) were first identified in patients with severe mycobacterial infections, and were considered to be an autoimmune phenocopy of inborn genetic errors of the IL-12/IFN-γ axis. More than 600 reported cases, most originating from Southeast Asia, have been diagnosed over the last decade. Specific HLA class II molecules are associated with these autoantibodies, which provide a genetic basis for the high prevalence of this immunodeficiency syndrome in certain ethnic groups. Salmonellosis and herpes zoster reactivation are observed in more than half the patients with AIGAs. Moreover, AIGAs have been shown to underlie severe Taralomyce marneffei infection in HIV-negative patients. AIGAs may, thus, be considered a new form of late-onset immunodeficiency conferring a predisposition not only to severe mycobacterial, but also to some bacterial and fungal infections.

Insufficient type I IFN immunity underlies life-threatening COVID-19 pneumonia

We established the COVID Human Genetic Effort (www.covidhge.com) to discover the human genetic and immunological bases of the vast interindividual clinical variability between humans infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We found that about 3% of patients with life-threatening coronavirus disease 2019 (COVID-19) pneumonia were ill because of inborn errors of genes controlling type I interferon (IFN)-dependent immunity (which controls influenza virus), and at least 10% of patients with life-threatening COVID-19 pneumonia had neutralizing auto-Abs against some of the 17 individual type I IFNs. These findings indicate that impaired type I IFN immunity underlies life-threatening COVID-19 pneumonia in at least 13% of patients. These discoveries pave the way for further research into unexplained severe cases, and provide a rationale for preventing and treating the disease in individuals at risk, with recombinant type I IFNs.

Clinical findings of Talaromyces marneffei infection among patients with anti-interferon-γ immunodeficiency: a prospective cohort study

Background

Talaromyces marneffei (T. marneffei) infection has been associated with adult-onset immunodeficiency due to anti-IFN-γ autoantibodies. We aimed to investigate the clinical features of non-HIV-infected patients with T. marneffei infection in southern China.

Methods

Between January 2018 and September 2020, we enrolled patients with T. marneffei infection who were HIV-negative (group TM, n = 42), including anti-IFN-γ autoantibody-positive (group TMP, n = 22) and anti-IFN-γ autoantibody-negative (group TMN, n = 20) patients and healthy controls (group HC, n = 40). Anti-IFN-γ autoantibodies were detected by ELISA. Clinical characteristics and clinical laboratory parameters were recorded.

Results

Compared with anti-IFN-γ autoantibody-negative patients with T. marneffei infection, anti-IFN-γ autoantibody-positive patients did not have underlying respiratory disease; more frequently exhibited dissemination of systemic infections with severe pleural effusion; had higher WBC counts, C-reactive protein levels, erythrocyte sedimentation rates, and neutrophil and CD8⁺ T cell counts; had lower hemoglobin levels; and were more likely to have other intracellular pathogen infections. Most of these patients had poor outcomes despite standardized antimicrobial therapy.

Conclusion

T. marneffei-infected patients with higher anti-IFN-γ autoantibody titers have more severe disease and complex clinical conditions.

Approach to the diagnosis and treatment of non-tuberculous mycobacterial disease

Non-tuberculous mycobacteria (NTM) is a collective name given to a group of more than 190 species of Mycobacterium. The clinical presentation for most NTM infections is non-specific, often resulting in delayed diagnosis. Further complicating matters is that NTM organisms can be difficult to isolate. Medications used to treat NTM infection can be difficult for patients to tolerate, and prolonged courses of anti-mycobacterial therapy are often required for adequate suppression or eradication. Herein, we review different NTM syndromes, appropriate diagnostic tests, and treatment regimens.

Natural History and Evolution of Anti-Interferon-γ Autoantibody-Associated Immunodeficiency Syndrome in Thailand and the United States

BACKGROUND

The natural history of anti-interferon-γ (IFN-γ) autoantibody-associated immunodeficiency syndrome is not well understood.

METHODS

Data of 74 patients with anti-IFN-γ autoantibodies at Srinagarind Hospital, Thailand, were collected annually (median follow-up duration, 7.5 years). Annual data for 19 patients and initial data for 4 patients with anti-IFN-γ autoantibodies at the US National Institutes of Health were collected (median follow-up duration, 4.5 years). Anti-IFN-γ autoantibody levels were measured in plasma samples.

RESULTS

Ninety-one percent of US patients were of Southeast Asian descent; there was a stronger female predominance (91%) in US than Thai (64%) patients. Mycobacterium abscessus (34%) and Mycobacterium avium complex (83%) were the most common nontuberculous mycobacteria in Thailand and the United States, respectively. Skin infections were more common in Thailand (P = .001), whereas bone (P < .0001), lung (P = .002), and central nervous system (P = .03) infections were more common in the United States. Twenty-four percent of Thai patients died, most from infections. None of the 19 US patients with follow-up data died. Anti-IFN-γ autoantibody levels decreased over time in Thailand (P < .001) and the United States (P = .017), with either cyclophosphamide (P = .01) or rituximab therapy (P = .001).

CONCLUSIONS

Patients with anti-IFN-γ autoantibodies in Thailand and the United States had distinct demographic and clinical features. While titers generally decreased with time, anti-IFN-γ autoantibody disease had a chronic clinical course with persistent infections and death. Close long-term surveillance for new infections is recommended.

Sweet Syndrome precipitated by Mycobacterium abscessus in a Laotian Man with Autoantibodies to Interferon Gamma

Autoantibodies to interferon γ, part of the first line of defense in the human immune response, constitutes a rare form of an acquired immunodeficiency in HIV-uninfected adults that can predispose to disseminated atypical mycobacterial infection. Particularly, this has been described in people of Southeast Asian origin. In this case report, we describe a previously healthy, Laotian man who presented with skin lesions consistent with Sweet syndrome that were later found to be precipitated by disseminated atypical mycobacterial disease. Extensive immunological workup revealed the patient to have autoantibodies to interferon γ, rendering him susceptible to this infection. Our report demonstrates a complex case with a multilayered diagnosis, while inviting perspective from multiple specialties. This enigmatic case emphasizes the importance of a broad differential with special attention to demographics while demonstrating the difficulty in treating certain atypical infections that are inherently multidrug resistant.

Minireview: Insights into anti-interferon-γ autoantibodies

The association between the presence of anti-interferon-γ autoantibodies and the onset of immunodeficiency with intracellular infections has been clearly established. No standard regimen to control the production of these pathogenic autoantibodies, apart from antimicrobial therapy to eliminate infections, contributes to the medical burden of this syndrome, which sometimes has a fatal outcome. In this review, we summarize the findings on anti-interferon-γ autoantibodies to facilitate further research and to provide guidance for treatment strategies.