Clinical outcome and laboratory markers for predicting disease activity in patients with disseminated opportunistic infections associated with anti-interferon-γ autoantibodies

Clinical features of talaromycosis in people living with HIV/AIDS (PWHA) and patients with anti-interferon-γ autoantibodies

BACKGROUND

Talaromycosis is increasingly reported in HIV-uninfected, immunocompromised individuals in an endemic area. The aim of this study was to compare the characteristics and mortality associated with talaromycosis in adult immunocompromised individuals caused by the anti-interferon-gamma autoantibody (anti-IFN- γ AAb) with those of people living with HIV/AIDS (PWHA).

METHODS

A retrospective cohort study was conducted at Maharaj Nakorn Chiang Mai Hospital, Thailand, in adults with confirmed HIV infection or anti-IFN- γ-AAbs diagnosed with talaromycosis.

RESULTS

Thirty-two patients with anti-IFN- γ-AAbs and 235 PWHA were included. Patients with anti-IFN- γ-AAbs were older and more likely to have comorbidities. PWHA were more likely to have constitutional symptoms, cough, dyspnea, diarrhea, splenomegaly, umbilicated skin lesions, abnormal chest radiographs, and fungemia. Patients with anti-IFN- γ-AAbs were more likely to have skin lesions such as macule/papules/nodules, abscesses and Sweet's syndrome, as well as bone and joint infections and higher white blood cell counts. The time from first symptom to treatment was longer in patients with anti-IFN- γ-AAbs (44.5 days vs. 30.0 days, p-value = 0.049). The 24-week mortality rate was 9.4% (3 patients) in patients with anti-IFN- γ-AAbs and 15.3% (36 patients) in PWHA (p-value = 0.372).

CONCLUSIONS

The clinical features of talaromycosis in patients with anti-IFN- γ-AAbs differed from PWHA. Clinicians in areas where talaromycosis is endemic should be aware of the different features of talaromycosis in patients with anti-IFN- γ AAbs.

Clinical characteristics of acquired anti-IFN-γ autoantibodies in patients infected with non-tuberculous mycobacteria: a prospective cohort study

BACKGROUND

Patients with positive anti-IFN-γ autoantibodies (AIGAs) are characterized by susceptibility to disseminated infection by multiple pathogens. The clinical characteristics of non-tuberculous mycobacterial (NTM) infection with AIGAs positivity remain unclear.

METHODS

A prospective cohort study was conducted at the First Affiliated Hospital of Guangxi Medical University from January 2021 to January 2024. A total of 93 patients diagnosed with NTM infection were divided into two groups: AIGAs-positive with NTM infection and AIGAs-negative with NTM infection. The clinical manifestations, laboratory data, imaging examination, and pathogens were analyzed to characterize the disease.

RESULTS

A total of 44 AIGAs-positive and 49 AIGAs-negative patients with NTM infection were enrolled. Disseminated infections were significantly more common among AIGAs-positive patients (P < 0.001), with frequent co-infections involving Talaromyces marneffei (TM) and viruses. Additionally, AIGAs-positive patients exhibited elevated inflammatory markers and immunoglobulins. In the AIGAs-positive group, lymph nodes, bones, skin, and blood were the most frequently affected sites. Chest CT scans exhibited a range of findings. Over a mean follow-up period of 36 months, 56.82% of patients with AIGAs positivity experienced exacerbations despite undergoing regular anti-NTM therapy.

CONCLUSIONS

AIGAs-positive patients with NTM infection exhibit elevated inflammatory markers, abnormal immune indicators, and coagulation function. Disseminated infections involving multiple organs are common, with frequent co-infection with TM and viruses. These patients may have unique symptoms, signs, and imaging findings compared to AIGAs-negative patients. Recurrence is common among these patients, highlighting the need for timely identification and intervention.

Clinical Characteristics Analysis of 30 Cases of Interferon-γ Autoantibody-Positive Patients with Concurrent Mycobacterial Infection: A 6-Year Retrospective Study

Purpose

This study aimed to investigate and elucidate the clinical characteristics, immune status, infection types and patterns, treatment responses, and disease progression in patients with positive anti-interferon-gamma (IFN-γ) autoantibodies in combination with Mycobacterium infections.

Patients and Methods

We conducted a retrospective analysis of clinical data from patients with positive anti-IFN-γ autoantibodies and concurrent Mycobacterial infections, including Mycobacterial infections (MTB) and non-tuberculous mycobacteria (NTM). The study included cases treated at the Fourth People's Hospital of Nanning, Guangxi, from 2018 to 2023. Data collected comprised symptoms, clinical signs, laboratory test results, imaging findings, and other relevant clinical information. Patients were also followed up to evaluate treatment responses and long-term therapeutic outcomes.

Results

A total of 30 patients with MTB and NTM infections were analyzed. The majority presented with common symptoms, such as cough, sputum production, weight loss, extrapulmonary tuberculosis (TB), and a range of opportunistic infections. Laboratory and imaging studies revealed complex infection patterns and various pathological changes. Treatment primarily involved targeted anti-infective therapy combined with immunosupportive measures. However, frequent treatment relapses and side effects were observed, resulting in two deaths.

Conclusion

Immune deficiency associated with positive anti-IFN-γ autoantibodies resembles the immunosuppression seen in advanced stages of human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS), rendering patients highly susceptible to opportunistic infections. These infections were predominantly caused by NTM, followed by MTB and Talaromyces marneffei (TM). This represents a novel immune deficiency syndrome that predisposes patients to a spectrum of opportunistic infections.

Utility of 18F-Fluorodeoxyglucose Positron Emission Tomography in Evaluating Disseminated Nontuberculous Mycobacterial Infection in Patients With Anti-interferon-γ Autoantibodies

Background

Managing disseminated nontuberculous mycobacterial (NTM) infection in patients with neutralizing anti-interferon-γ autoantibodies (AIGAs) poses substantial challenges due to the lack of established treatment guidance and predictive tools for clinical outcomes. In this study, we investigated the utility of 18F-fluorodeoxyglucose (2-[18F]FDG) positron emission tomography (PET) in guiding treatment decisions, with a focus on its ability to predict rehospitalization outcomes.

Methods

We conducted a post hoc analysis of the first available 2-[18F]FDG PET scans of patients with AIGAs and disseminated NTM infection from a prospective observational multicenter cohort. Cox proportional hazards regression was used to determine predictors for disease-related rehospitalization within 1 year of the examination.

Results

Of the patients with AIGAs evaluated, 41.9% required rehospitalization within 1 year following the initial 2-[18F]FDG PET evaluation. Slowly growing mycobacteria were isolated in 64.5% of patients. Multivariable analysis identified splenic involvement (adjusted hazard ratio, 7.97; 95% CI, 2.34-27.16; P < .001) as a significant predictor of disease-related rehospitalization within 1 year following the examination. Moreover, mediastinal node involvement (adjusted odds ratio, 14.77; 95% CI, 1.01-216.76; P = .049) and axial skeleton involvement (adjusted odds ratio, 14.93; 95% CI, 1.11-201.43; P = .042) were significantly associated with the isolation of slowly growing mycobacteria.

Conclusions

2-[18F]FDG PET appears useful in initial evaluation of disease extent and microbiology in patients with AIGAs and disseminated NTM infection. Identifying splenic involvement through this modality may help recognize patients at increased risk of disease-related rehospitalization within 1 year. These findings suggest that 2-[18F]FDG PET could inform management decisions in this challenging population.

A homogeneous bioluminescent inhibition immunoassay to detect anti-interferon gamma antibodies

Adult-onset immunodeficiency with antibodies to interferon-γ (AOID with AIGA) is a rare, acquired immunodeficiency causing susceptibility to disseminated non-tuberculous mycobacteria and other intracellular opportunistic infections. The diagnosis depends on demonstrating the presence of endogenous anti-interferon-γ antibodies (AIGA) that suppress Th1 cell-mediated immunity. Bioluminescent immunoassays are a newly emerging immunoassay format which utilize the action of bioluminescent enzymes on a substrate for specific analyte detection. In short, detecting antibodies are conjugated with a bioluminescent enzyme. The detecting antibodies bind the analyte of interest and produce light (luminescence) after addition of a substrate. The purpose of this study was to evaluate two newly developed bioluminescent immunoassays using Lumit® (Promega) technology as a diagnostic test for AOID with AIGA. Specific aims included the clinical validation of a new inhibition bioluminescent immunoassay technique to detect AIGA which block detection of interferon-γ (IFN-γ) in vitro and correlation of inhibition bioluminescent immunoassay results with AOID with AIGA disease status. Two bioluminescent inhibition immunoassays were developed. One which adapted an existing kit from Promega (Lumit® Human IFN-γ Immunoassay) and the other which was developed in house. Eighty-seven healthy controls and 48 patients with previously diagnosed AOID with AIGA were recruited and tested using these two methods. Results showed both bioluminescent inhibition immunoassays were able to clearly discriminate between AOID with AIGA patients and healthy controls. The mean inhibition percentage between patient groups correlated with disease activity. Both assays appeared to be more sensitive when compared to the existing inhibition ELISA.

Advances in the understanding of talaromycosis in HIV-negative patients (especially in children and patients with hematological malignancies): A comprehensive review

Talaromyces marneffei (T. marneffei) stands out as the sole thermobiphasic fungus pathogenic to mammals, including humans, within the fungal community encompassing Ascomycota, Eurotium, Eurotiumles, Fungiaceae, and Cyanobacteria. Thriving as a saprophytic fungus in its natural habitat, it transitions into a pathogenic yeast phase at the mammalian physiological temperature of 37°C. Historically, talaromycosis has been predominantly associated with human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS), classified among the three primary opportunistic infections linked with AIDS, alongside tuberculosis and cryptococcosis. As advancements are made in HIV/AIDS treatment and control measures, the incidence of talaromycosis co-infection with HIV is declining annually, whereas the population of non-HIV-infected talaromycosis patients is steadily increasing. These patients exhibit diverse risk factors such as various types of immunodeficiency, malignant tumors, autoimmune diseases, and organ transplantation, among others. Yet, a limited number of retrospective studies have centered on the clinical characteristics and risk factors of HIV-negative talaromycosis patients, especially in children and patients with hematological malignancies, resulting in an inadequate understanding of this patient cohort. Consequently, we conducted a comprehensive review encompassing the epidemiology, pathogenesis, risk factors, clinical manifestations, diagnosis, treatment, and prognosis of HIV-negative talaromycosis patients, concluding with a prospectus of the disease's frontier research direction. The aim is to enhance comprehension, leading to advancements in the diagnosis and treatment rates for these patients, ultimately improving their prognosis.

Efficacy of Bortezomib for Treating Anti-Interferon-Gamma Autoantibody-Associated Adult-Onset Immunodeficiency Syndrome

BACKGROUND

Currently, there is no effective treatment for adult-onset immunodeficiency (AOID) syndrome with anti-interferon-gamma autoantibodies (anti-IFN-γ-auto-Abs). This study aimed to investigate the effectiveness of bortezomib (BTZ) for decreasing anti-IFN-γ-auto-Abs.

METHODS

A pre- and post-intervention study was conducted from February 2017 through June 2019 at Siriraj Hospital (Bangkok, Thailand). Five patients were invited to receive once-weekly BTZ (1.3 mg/m2 body surface area) subcutaneously for 8 weeks followed by oral cyclophosphamide (1 mg/kg/d) for 4 months. The primary outcomes were the difference in antibody level at 8 and 48 weeks compared with baseline and the incidence of serious adverse events (AEs). The secondary outcome was the occurrence of opportunistic infections (OIs) during the 72 weeks after starting BTZ.

RESULTS

The median patient age was 46 years (range, 34-53). All patients had 3-5 OIs prior to enrollment. All patients were receiving antimycobacterial agents for treatment of nontuberculous mycobacterial infection at enrollment. There was no significant difference in the mean optical density of auto-Abs at 8 weeks (3.73 ± 0.72) or 48 weeks (3.74 ± 0.53) compared with baseline (3.84 ± 0.49; P = .336 and P = .555, respectively). However, after serum dilution, the antibody titer nonsignificantly decreased 8-16 weeks after BTZ initiation (P = .345). Ten OIs were observed 24-72 weeks after BTZ initiation.

CONCLUSIONS

Treatment with BTZ followed by cyclophosphamide yielded no significant decrease in antibody titer levels, and 10 OIs were observed during 24-72 weeks of BTZ treatment. No serious AEs were observed. Combining rituximab with BTZ is likely necessary to prevent generation of new autoantibody-producing plasma cells. Clinical Trials Registration. NCT03103555.

Neutralizing IFN-γ autoantibodies are rare and pathogenic in HLA-DRB1*15:02 or 16:02 individuals

BACKGROUNDWeakly virulent environmental mycobacteria (EM) can cause severe disease in HLA-DRB1*15:02 or 16:02 adults harboring neutralizing anti-IFN-γ autoantibodies (nAIGAs). The overall prevalence of nAIGAs in the general population is unknown, as are the penetrance of nAIGAs in HLA-DRB1*15:02 or 16:02 individuals and the proportion of patients with unexplained, adult-onset EM infections carrying nAIGAs.METHODSThis study analyzed the detection and neutralization of anti-IFN-γ autoantibodies (auto-Abs) from 8,430 healthy individuals of the general population, 257 HLA-DRB1*15:02 or 16:02 carriers, 1,063 patients with autoimmune disease, and 497 patients with unexplained severe disease due to EM.RESULTSWe found that anti-IFN-γ auto-Abs detected in 4,148 of 8,430 healthy individuals (49.2%) from the general population of an unknown HLA-DRB1 genotype were not neutralizing. Moreover, we did not find nAIGAs in 257 individuals carrying HLA-DRB1* 15:02 or 16:02. Additionally, nAIGAs were absent in 1,063 patients with an autoimmune disease. Finally, 7 of 497 patients (1.4%) with unexplained severe disease due to EM harbored nAIGAs.CONCLUSIONThese findings suggest that nAIGAs are isolated and that their penetrance in HLA-DRB1*15:02 or 16:02 individuals is low, implying that they may be triggered by rare germline or somatic variants. In contrast, the risk of mycobacterial disease in patients with nAIGAs is high, confirming that these nAIGAs are the cause of EM disease.FUNDINGThe Laboratory of Human Genetics of Infectious Diseases is supported by the Howard Hughes Medical Institute, the Rockefeller University, the St. Giles Foundation, the National Institutes of Health (NIH) (R01AI095983 and U19AIN1625568), the National Center for Advancing Translational Sciences (NCATS), the NIH Clinical and Translational Science Award (CTSA) program (UL1 TR001866), the French National Research Agency (ANR) under the "Investments for the Future" program (ANR-10-IAHU-01), the Integrative Biology of Emerging Infectious Diseases Laboratory of Excellence (ANR-10-LABX-62-IBEID), ANR-GENMSMD (ANR-16-CE17-0005-01), ANR-MAFMACRO (ANR-22-CE92-0008), ANRSECTZ170784, the French Foundation for Medical Research (FRM) (EQU201903007798), the ANRS-COV05, ANR GENVIR (ANR-20-CE93-003), and ANR AI2D (ANR-22-CE15-0046) projects, the ANR-RHU program (ANR-21-RHUS-08-COVIFERON), the European Union's Horizon 2020 research and innovation program under grant agreement no. 824110 (EASI-genomics), the Square Foundation, Grandir - Fonds de solidarité pour l'enfance, the Fondation du Souffle, the SCOR Corporate Foundation for Science, the Battersea & Bowery Advisory Group, William E. Ford, General Atlantic's Chairman and Chief Executive Officer, Gabriel Caillaux, General Atlantic's Co-President, Managing Director, and Head of business in EMEA, and the General Atlantic Foundation, Institut National de la Santé et de la Recherche Médicale (INSERM) and of Paris Cité University. JR was supported by the INSERM PhD program for doctors of pharmacy (poste d'accueil INSERM). JR and TLV were supported by the Bettencourt-Schueller Foundation and the MD-PhD program of the Imagine Institute. MO was supported by the David Rockefeller Graduate Program, the Funai Foundation for Information Technology (FFIT), the Honjo International Scholarship Foundation (HISF), and the New York Hideyo Noguchi Memorial Society (HNMS).

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.

Disseminated tuberculosis, CMV viraemia & haemophagocytic-lymphohistiocystosis syndrome in an adult patient with anti- IFNγ autoantibodies - case report and brief review

We report a case of an adult female with disseminated tuberculosis, cytomegalovirus viraemia and haemophagocytic-lymphohistiocystosis syndrome associated with neutralizing anti- interferon gamma (IFNγ) autoantibodies demonstrated by absent IFNγ stimulated STAT1 phosphorylation in the presence of patient sera. A brief review of immunodeficiency caused by anti-IFNγ autoantibodies is also described.

Disseminated coinfection with Mycobacterium Avium complex and Mycobacterium Kansasii in a patient with idiopathic CD4+ lymphocytopenia: A case report

Simultaneously disseminated coinfection with two species of nontuberculous mycobacteria (NTM) is extremely rare and had been reported only in immunocompromised individuals. Here, we report a 59-year-old Thai man, previously healthy. He presented with a 2-month history of prolonged fever, constitutional symptoms, and hepatosplenomegaly. His chest and abdomen computed tomography illustrated multiple enlarged mediastinal lymph nodes accompanied with multifocal crazy-paving appearance in both lungs and hepatosplenomegaly. Endobronchial ultrasound-guided transbronchial needle aspiration was performed on the mediastinal nodes. The pathologic findings were necrotizing granulomatous lymphadenitis with numerous AFB-positive bacilli. Blood culture subsequently isolated M. intracellulare, while BAL and lymph node culture isolated M. intracellulare and M. kansasii, which confirmed species by multiplex PCR and 16s rRNA sequencing. Idiopathic CD4+ lymphocytopenia (ICL) was diagnosed as the cause of secondary immune deficiency. Intravenous imipenem, amikacin, and azithromycin were administered as an empirical antibiotic regimen for 4 weeks, then substituted to oral rifampicin, clarithromycin, moxifloxacin, and ethambutol as definitive regimen. Unfortunately, it was found that he had died unexpectedly at home after 4 months of treatment, possibly related to this illness. In our view, patients with severe disseminated NTM disease should be evaluated to explore a secondary immune deficiency disorder. An ICL is a rare heterogenous syndrome but should be considered.

Prevalence and clinical manifestations of cutaneous findings in patients with adult-onset immunodeficiency due to anti-interferon gamma autoantibodies: an eight-year retrospective study

BACKGROUND

Cutaneous findings in adult-onset immunodeficiency due to anti-interferon gamma autoantibodies (anti-IFN-γ autoAbs) are common. Currently, data on this topic are scarce.

METHODS

We retrospectively reviewed medical records of 202 skin episodes from 77 patients diagnosed with adult-onset immunodeficiency due to anti-IFN-γ autoAbs. The exclusion of drug eruptions left 180 episodes from 74 patients for further analysis.

RESULTS

Reactive dermatosis was diagnosed in 66.1%, followed by disseminated skin infection (18.3%) and local skin infection (15.6%). Neutrophilic dermatosis (ND) tended to appear on the upper part of bodies, while leg lesions were common in the non-ND. Disseminated infection occurred more frequently with ND. Mycobacterium abscessus was the most common pathogen of concomitant infection. Remission was achieved in 21.6% and was significantly associated with females.

CONCLUSION

Reactive dermatosis was the most common skin manifestation. ND was found in the upper part of bodies and associated with disseminated infection. Drug-free remission was scarcely achieved.

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.

Health related quality of life in anti interferon γ autoantibody associated immunodeficiency syndrome measured with EQ5D5L and SF36

The anti-IFN-γ disease is a rare condition characterized by recurrent and persistent infections, potentially impacting the quality of life (QoL). However, comprehensive data on QoL in this population are lacking. This study aims to evaluate the QoL of Anti-IFN-γ patients compared to healthy control and explore potential differences in QoL between patients in the active and remission stages. A cross-sectional study design was conducted, recruiting 38 Anti-IFN-γ patients and 38 sex- and age-matched healthy controls. QoL assessment utilized the 5-level EuroQol-5 Dimension (EQ-5D-5L) and the 36-Item Short Form Health Survey (SF-36). The Anti-IFN-γ group had a mean age of 57.37 (± 10.32) years, with females comprising 60.53%. Among the Anti-IFN-γ patients, 55.26% were classified as having active disease. 63% of Anti-IFN-γ patients received Immunosuppressive treatments. Anti-IFN-γ disease exhibited a significant negative impact on HRQoL, as evidenced by lower utility scores in EQ-5D-5L and lower physical and mental component scores in SF-36 across various domains, including physical function, role physical, general health, bodily pain, social functioning, role emotion and mental health, compared to healthy controls. Additionally, patients in the active disease displayed lower scores in multiple domains, including bodily pain, general health, role emotion and mental health, and a lower utility score in EQ-5D-5L compared to patients in remission. The anti-IFN-γ disease significantly impairs the HRQoL of affected individuals compared to healthy controls. However, effective treatment leading to remission holds promise for improving the HRQoL of patients with Anti-IFN-γ disease.

Inborn Errors of Immunity and Autoimmune Disease

Autoimmunity may be a manifestation of inborn errors of immunity, specifically as part of the subgroup of primary immunodeficiency known as primary immune regulatory disorders. However, although making a single gene diagnosis can have important implications for prognosis and management, picking patients to screen can be difficult, against a background of a high prevalence of autoimmune disease in the population. This review compares the genetics of common polygenic and rare monogenic autoimmunity, and explores the molecular mechanisms, phenotypes, and inheritance of autoimmunity associated with primary immune regulatory disorders, highlighting the emerging importance of gain-of-function and non-germline somatic mutations. A novel framework for identifying rare monogenic cases of common diseases in children is presented, highlighting important clinical and immunologic features that favor single gene disease and guides clinicians in selecting appropriate patients for genomic screening. In addition, there will be a review of autoimmunity in non-genetically defined primary immunodeficiency such as common variable immunodeficiency, and of instances where primary autoimmunity can result in clinical phenocopies of inborn errors of immunity.

Diagnostic and Therapeutic Challenges in Disseminated Mycobacterium colombiense Infection Caused by Interferon-γ Neutralizing Autoantibodies

Adult-onset immunodeficiency due to interferon-γ-neutralizing autoantibodies (nIFNγ-autoAbs) can remain underdiagnosed. We present a case of severe Mycobacterium colombiense infection with nIFNγ-autoAbs. To ensure early diagnosis, clinicians should have a high index of suspicion in patients of Asian descent with opportunistic infections and perform QuantiFERON-TB assay for disease screening.

Severe COVID-19 represents an undiagnosed primary immunodeficiency in a high proportion of infected individuals

Since the emergence of the COVID-19 pandemic in early 2020, a key challenge has been to define risk factors, other than age and pre-existing comorbidities, that predispose some people to severe disease, while many other SARS-CoV-2-infected individuals experience mild, if any, consequences. One explanation for intra-individual differences in susceptibility to severe COVID-19 may be that a growing percentage of otherwise healthy people have a pre-existing asymptomatic primary immunodeficiency (PID) that is unmasked by SARS-CoV-2 infection. Germline genetic defects have been identified in individuals with life-threatening COVID-19 that compromise local type I interferon (IFN)-mediated innate immune responses to SARS-CoV-2. Remarkably, these variants - which impact responses initiated through TLR3 and TLR7, as well as the response to type I IFN cytokines - may account for between 3% and 5% of severe COVID-19 in people under 70 years of age. Similarly, autoantibodies against type I IFN cytokines (IFN-α, IFN-ω) have been detected in patients' serum prior to infection with SARS-CoV-2 and were found to cause c. 20% of severe COVID-19 in the above 70s and 20% of total COVID-19 deaths. These autoantibodies, which are more common in the elderly, neutralise type I IFNs, thereby impeding innate antiviral immunity and phenocopying an inborn error of immunity. The discovery of PIDs underlying a significant percentage of severe COVID-19 may go some way to explain disease susceptibility, may allow for the application of targeted therapies such as plasma exchange, IFN-α or IFN-β, and may facilitate better management of social distancing, vaccination and early post-exposure prophylaxis.

Adult-onset immunodeficiency due to anti-interferon-gamma autoantibody-associated Sweet syndrome: A distinctive entity

Sweet syndrome (SS) has been increasingly reported in patients with adult-onset immunodeficiency (AOID) due to anti-interferon-γ autoantibody who also have concomitant opportunistic infections, especially disseminated non-tuberculous mycobacterial infection (dNTMI). A retrospective study retrieving data from 2011 through 2020 was conducted. We compared clinical characteristics of SS with and without AOID and generated the prediction model and examined the interaction between AOID and dNTMI in the occurrence of SS. Lymphadenopathy, pustular lesions, and leukocytosis are the significant predictors for AOID-associated SS. Adjusted risk differences were 0.58 (95% confidence interval [CI], 0.33-0.83), 0.21 (95% CI, 0.02-0.39), and 0.24 (95% CI, 0.01-0.47), respectively. Based on the analysis of aggregated cross-sectional data, both the overall and the direct effect of AOID increased the prevalence of SS. The indirect effect of AOID on the occurrence of SS might also be mediated through dNTMI or other common opportunistic infections. In addition, there was a trend of positive additive interaction between AOID and dNTMI. Although the test of additive interaction did not reveal statistically significant results, a deviation from additivity of isolated effects might suggest potential causal interaction between AOID and dNTMI. The distinctive clinical syndrome comprising lymphadenopathy, pustular lesions, and leukocytosis in patients with SS should raise the awareness of clinicians to the potential of underlying AOID.

Mycobacterial lymphadenitis without granuloma formation in a patient with anti-interferon-gamma antibodies

A previously healthy 49-year-old Japanese woman presented with cervical lymph node swelling and tenderness. Lymph node biopsy revealed reactive lymphadenitis without granulomas. No malignant cells were found, and no acid-fast positive bacilli were identified by Ziehl-Neelsen staining. She was treated unsuccessfully with various antibiotics, and it was very challenging to reach a diagnosis. ¹⁸F-Fluorodeoxyglucose (¹⁸F-FDG) uptake in bones was evaluated using positron emission tomography-computed tomography (PET-CT), and disseminated mycobacterial infection was suspected. The interferon-gamma (IFN-γ) release assays QuantiFERON (QFT) and T-SPOT were used to diagnose tuberculosis infection. On testing, a difference in mitogen response was found between these assays. The response was low for QFT but adequate for T-SPOT, suggesting the presence of anti-IFN-γ antibodies. This difference depended on whether the patient's plasma (including anti-IFN-γ antibodies) was used within the assay system. Mycobacterium abscessus was isolated from lymph node cultures, and plasma anti-IFN-γ antibodies were confirmed. The patient was diagnosed with disseminated M. abscessus infection with underlying adult-onset immunodeficiency caused by anti-IFN-γ antibodies. Granulomas are a pathological hallmark of mycobacterial infection, but may not fully form in immunodeficient patients. Clinicians should be aware of the possibility of mycobacterial infection without granuloma formation due to anti-IFN-γ antibodies.

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.

Treatment Dilemmas in Disseminated Nontuberculous Mycobacterial Infections With Interferon-gamma Autoantibodies

Disseminated Mycobacterium avium complex (dMAC) is typically seen in individuals with impaired cell-mediated immunity and is best described in those with HIV. Recently, cases have been described in otherwise healthy individuals with neutralizing antibodies to interferon-gamma (nIFNγ-autoAb), especially in patients of Southeast Asian descent. Treatment is often refractory to mycobacterial therapies, and the use of rituximab and other immunomodulatory agents has been explored. We report 3 cases of dMAC with nIFN-γ-autoAb and review the available literature on treatment strategies to provide a framework for the management of patients with refractory infections in the context of neutralizing antibodies to interferon-gamma.

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.

Talaromycosis marneffei of the Cervical Spine: An Unusual Infection

Talaromyces marneffei infection (TMI) causing vertebral osteomyelitis of the cervical spine is extremely rare. TMI in an HIV-uninfected patient is also unusual. This report presents the successful treatment of an HIV-uninfected TMI patient who underwent C6 and T1 vertebrectomies, bone grafting, and anterior cervical plating accompanied by antifungal therapy. A 63-year-old woman was diagnosed with adult-onset immune deficiency. She suddenly developed progressive neck pain without neurologic deficit. The plain radiographs and magnetic resonance imaging showed inflammation and abscess formation along the prevertebral area from C3-4 to T2-3 with vertebral body destruction. Intraoperative pus culture and tissue specimens were determined to be T marneffei. The patient was treated intravenously with amphotericin B deoxycholate for 4 weeks (0.6 mg/kg/d) and oral itraconazole (400 mg/d) for 12 months. Over a 2 consecutive year follow-up period, she achieved a full recovery with an absence of neck pain.

Recurrent disseminated Mycobacterium avium in a female patient from Thailand with anti-interferon-gamma autoantibodies: dilemma on treatment approach

Anti-interferon-gamma (IFN-γ) autoantibodies has been recognised as an adult-onset immunodeficiency in the past decade in people who originate from Southeast Asia. These patients are susceptible to particular opportunistic infections, especially non-tuberculous mycobacteria (NTM). We present the case of a woman whom originally came from Thailand with disseminated Mycobacterium avium complex infection (pleural, pericardium, bloodstream and lung parenchymal involvement). Her infection continued to progress while receiving proper antibiotic treatment. Once high titre neutralising anti-IFN-γ autoantibodies were detected, rituximab was added as adjunctive treatment. The patient had remarkable clinical improvement against persistence of anti-IFN-γ autoantibodies. Although her lung disease has improved, the patient continues on triple therapy for NTM. The kinetics of anti-IFN-γ autoantibodies in the context of clinical progression, indication and length for rituximab and triple therapy is discussed in view of the current literature.

Diagnosis of NTM active infection in lymphadenopathy patients with anti-interferon-gamma auto-antibody using inhibitory ELISA vs. indirect ELISA

The anti-interferon-gamma (IFN-gamma) autoantibody is a known cause of opportunistic non-tuberculous mycobacterial (NTM) infection in adults. Diagnosis of those patients is difficult due to the low sensitivity of bacterial culture, and because detection of the neutralizing autoantibody needs special laboratory devices. We conducted a retrospective review of indirect and inhibitory ELISA, both used for detection of anti-IFN-gamma auto-antibody in 102 patients with lymphadenopathies. We assessed hospital records of NTM isolation and/or diagnosis of NTM infection. The review revealed the compatible sensitivity and superior specificity and predictive values for inhibitory ELISA over against indirect ELISA—the latter achieving 100% specificity and positive predictive value for diagnosis of NTM infection in patients with lymphadenopathies. The results confirm functional assays that show plasma samples from NTM-infected patients with positive results by either indirect and/or inhibitory ELISA are IFN-gamma neutralizing autoantibodies. The inhibitory titer of anti-IFN-gamma auto-antibody can be used to distinguish patients with active from inactive NTM infection. Inhibitory ELISA is thus a practical, rapid, high performance tool for routine detection of anti-IFN-gamma autoantibody and NTM infection diagnosis before confirmation, enabling a timely therapeutic strategy for active infection treatment.

Serum Anti-interferon-γ Autoantibody Titer as a Potential Biomarker of Disseminated Non-tuberculous Mycobacterial Infection

PURPOSE

In the past decade, the relationship between naturally occurring interferon-γ-neutralizing autoantibodies (IFNγ-Ab) and disseminated non-tuberculous mycobacteria (NTM) infection has been established. Furthermore, immune suppressive therapy aimed at the suppression of antibody production has shown efficacy as a supportive treatment. However, the nature of antibody behavior and antibody titer during the course of this disease, as well as the pathophysiological significance of IFNγ-Ab, has not yet been fully elucidated.

METHODS

Thirteen Japanese subjects suffering from disseminated NTM (dNTM) infection with IFNγ-Ab were evaluated. The fluctuation of IFNγ-Ab titer and the neutralizing capacity against IFN-γ during the course of the disease were retrospectively analyzed. IFNγ-Ab titers in the sera were quantified using an enzyme-linked immunosorbent assay; neutralizing capacity was evaluated via flow cytometry.

RESULTS

Serum antibody titers were not constant during the treatment period and varied over the course of the disease. The antibody titer decreased when the disease was improved by anti-mycobacterial treatment (p < 0.01) and increased as the disease progressed (p < 0.05). Even after the antibody titer decreased, the neutralizing capacity against IFN-γ was maintained by individual sera.

CONCLUSIONS

Despite the improvement in the pathological condition via treatment, the patients' sera maintained neutralizing capacity against IFN-γ. Antibody titer fluctuated over the course of the disease and exhibited potential as a biomarker for judgment of the disease state.

A case report of Talaromyces marneffei Oro-pharyngo-laryngitis: a rare manifestation of Talaromycosis

Background

The incidence of Taralomyces marneffei infection in HIV-infected individuals has been decreasing, whereas its rate is rising among non-HIV immunodeficient persons, particularly patients with anti-interferon-gamma autoantibodies. T. marneffei usually causes invasive and disseminated infections, including fungemia. T. marneffei oro-pharyngo-laryngitis is an unusual manifestation of talaromycosis.

Case presentation

A 52-year-old Thai woman had been diagnosed anti-IFNɣ autoantibodies for 4 years. She had a sore throat, odynophagia, and hoarseness for 3 weeks. She also had febrile symptoms and lost 5 kg in weight. Physical examination revealed marked swelling and hyperemia of both sides of the tonsils, the uvula and palatal arches including a swelling of the epiglottis, and arytenoid. The right tonsillar biopsy exhibited a few intracellular oval and elongated yeast-like organisms with some central transverse septum seen, which subsequently grew a few colonies of T. marneffei on fungal cultures. The patient received amphotericin B deoxycholate 45 mg/dayfor 1 weeks, followed by oral itraconazole 400 mg/day for several months. Her symptoms completely resolved without complication.

Conclusion

In patients with anti-IFN-ɣ autoantibodies, T. marneffei can rarely cause a local infection involving oropharynx and larynx. Fungal culture and pathological examination are warranted for diagnosis T. marneffei oro-pharyngo-laryngitis. This condition requires a long term antifungal therapy.