
==== Front
Emerg Microbes Infect
Emerg Microbes Infect
Emerging Microbes & Infections
2222-1751
Taylor & Francis

39178284
2396887
10.1080/22221751.2024.2396887
Version of Record
Research Article
Research Article
Clinical immunological characteristics of anti-interferon-γ autoantibodies syndrome: a 3 year prospective cohort study
EMERGING MICROBES & INFECTIONS
S. LIANG ET AL.
Liang Siqiao a*
Liang Hanlin a*
Huang Xuemei a*
Liang Xiaona a
Chen Ni a
Xiao Rong a
Luo Zengtao a
Chen Quanfang a
Zhong Xinxin b
Deng Jingmin a
Huang Jie c
Li Meihua a
Yang Meiling a
Zeng Wen a
Tang Haijuan a
Jiang Jing a
Qin Shouming a
Wei Zhen d
Wu Siyao a
Ning Yan a
Wang Ke a
Cao Fu b
Zhang Jiujin b
Wei Qing d
Xu Chengqiong e
Luo Honglin f
Song Jian g
Li Pei h
Feng Xiaokai i
Yang Chenlu j
Lei Jieping k
Wang Hongwei l
Cao Bin m
He Zhiyi a
a Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Guangxi Medical University, Nanning, People’s Republic of China
b Department of Respiratory and Critical Care Medicine, Red Cross Hospital of Yulin City, Yulin, People’s Republic of China
c Department of Tuberculosis, Nanning Fourth People's Hospital, Nanning, People’s Republic of China
d Department of Respiratory and Critical Care Medicine, The People Hospital of Hechi, Hechi, People’s Republic of China
e Department of Respiratory and Critical Care Medicine, The Second People’s Hospital of Qinzhou, Qinzhou, People’s Republic of China
f Institute of Oncology, Guangxi Academy of Medical Sciences, Nanning, People’s Republic of China
g Institute of Cardiovascular Sciences, Guangxi Academy of Medical Sciences, The People’s Hospital of Guangxi Zhuang Autonomous Region, Nanning, People’s Republic of China
h Infectious Diseases Division, KingMed Diagnostics, Guangzhou, People’s Republic of China
i Department of Pulmonary and Critical Care Medicine, Beijing Chao-yang Hospital, Beijing, People’s Republic of China
j Department of Epidemiology and Biostatistics, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, People’s Republic of China
k Department of Clinical Research and Data Management, Center of Respiratory Medicine, China–Japan Friendship Hospital, Beijing, People’s Republic of China
l Basic Medical College, Medical School of Nanjing University, Nanjing, People’s Republic of China
m Department of Pulmonary and Critical Care Medicine, China–Japan Friendship Hospital, Beijing, People’s Republic of China
CONTACT Zhiyi He zhiyi-river@163.com Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Guangxi Medical University, No.6 Shuang Yong Road, Nanning, Guangxi 530021, People’s Republic of China
Bin Cao caobin_ben@163.com Department of Pulmonary and Critical Care Medicine, China–Japan Friendship Hospital, No. 2 East Yinghua Road, Chaoyang District, Beijing 100029, People's Republic of China
Hongwei Wang hwang@nju.edu.cn Medical School of Nanjing University, No.22 Hankou Road, Nanjing 210993, People's Republic of China
* Authors contributed equally to this work

Supplemental data for this article can be accessed online at https://doi.org/10.1080/22221751.2024.2396887

23 8 2024
2024
23 8 2024
13 1 239688710 5 2024
24 7 2024
22 8 2024
Nova techset27 8 2024
Converted to JATS 1.2 by Nova Techset27 8 2024
© 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group, on behalf of Shanghai Shangyixun Cultural Communication Co., Ltd
2024
The Author(s)
https://creativecommons.org/licenses/by-nc/4.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. The terms on which this article has been published allow the posting of the Accepted Manuscript in a repository by the author(s) or with their consent.

ABSTRACT

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.

KEYWORDS

AIGAs
infection
immunological characteristics
glucocorticoid
Guangxi Science and Technology Program 2023AB22055 Central Leading Local Science and Technology Development Fund Project 2023ZYZX1021 This work was supported by the Guangxi Key Technologies R&D Program [grant number 2023AB22055]; Central Leading Local Science and Technology Development Fund Project [grant number 2023ZYZX1021].
==== Body
pmcIntroduction

Anti-interferon (IFN)-γ autoantibodies (AIGAs) syndrome is a newly identified type of adult-onset immunodeficiency syndrome, which is related to the presence of neutralizing AIGAs with multiple opportunistic infections [1]. AIGAs with neutralizing capabilities can disrupt the binding of IFN-γ to its receptors, inhibiting the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway and STAT-1 phosphorylation [1,2]. This impairing macrophage defense against intracellular pathogens, such as Talaromyces marneffei (TM) and nontuberculous mycobacteria (NTM) [1,3,4].

The AIGAs syndrome exhibits a distinct regional distribution, with a high prevalence primarily in Southeast Asia [1,5–7]. Guangxi, in the south of China, is a high-incidence area. We previously conducted a study from 2010 to 2020 on TM infection in non- human immunodeficiency virus (HIV) patients in our hospital. The results showed that non-HIV patients with TM infection had a poorer prognosis compared to HIV patients, and AIGAs were identified as a significant cause of TM in non-HIV patients [8]. Some of the non-HIV patients included in this study were found to be AIGAs positive.

AIGAs syndrome is characterized by opportunistic infections. Despite appropriate antimicrobial treatment, recurrent infections persist [9,10]. This may be due to high levels of AIGAs produced by plasma cells, which can impact immune status. Previous studies have reported abnormal immune indices in AIGAs-positive patients, including elevated globulin (GLB) and immunoglobulin (Ig) G levels, as well as decreased CD4+ T cells [1,11]. However, long-term systematic observation is rare.

Current knowledge on AIGAs syndrome is largely based on retrospective analyses of existing data. However, most studies are limited by small sample sizes, varying case definitions, and inconsistent evaluations of disease progression and outcomes. The fluctuations in AIGAs titer remain unclear, and currently there is no standardized approach for managing AIGAs syndrome. This study analyses detailed clinical data from 135 AIGAs-positive patients, analysing their clinical immunological characteristics, and evaluates the effectiveness of glucocorticoid treatment.

Methods

Study design and oversight

A 36-month prospective clinical study was conducted in the First Affiliated Hospital of Guangxi Medical University from January 2021 to December 2023. The inclusion criteria for all subjects were infections caused by TM, NTM, or other opportunistic pathogens. The exclusion criteria were a history of HIV infection or acquired immune deficiency syndrome (AIDS). Subjects were divided into AIGAs-positive and AIGAs-negative groups based on serum AIGAs levels.

Comprehensive clinical and laboratory data were collected at the time of initial diagnosis for all subjects. Subsequently, data on the frequency of exacerbations and clinical outcomes were prospectively collected for all patients. A subset of AIGAs-positive patients was followed up at intervals of 1, 3, 6, 9 months, and 1 year post-discharge for additional data collection. This included assessments of AIGAs titer, immune indices, and specific clinical manifestations.

Glucocorticoid is recommended for AIGAs-positive patients in the stable phase and those without contraindications, based on the following criteria: AIGAs titer is equal to 1: 2500;

Abnormal immune indices, including elevated levels of IgG, IgE, IgG4, GLB, and erythrocyte sedimentation rate (ESR), or discomfort like rash and fatigue, were observed when the infection was controlled;

Administration of prednisone <0.5 mg/ (kg per day) (or other glucocorticoid with equivalent potency) for a minimum of 4 weeks or longer.

Case definition

Positive indirect Enzyme-Linked Immunosorbent Assay (ELISA) results and confirmed neutralizing capacity via Western Blot (WB) indicated positive AIGAs. Negative ELISA results meant negative AIGAs. A decreased AIGAs titer was defined as a reduction from 1:2500–1:500, 1:100, or 0, or from 1:500–1:100 or 0.

The diagnostic criteria for Talaromyces marneffei (TM) infection encompass the following: Next-generation sequencing (NGS) on qualified specimens, including bronchoalveolar lavage fluid, lymph nodes, purulent exudates, blood, and sputum, to identify TM-specific sequences;

Culturing of qualified specimens at 25°C or 37°C to isolate TM;

Pathological examination demonstrating TM fungal spores.

The presence of one or more of these criteria is sufficient for a diagnosis of TM infection.

The diagnosis of nontuberculous mycobacteria (NTM) infection adheres to the guidelines for the diagnosis and treatment of non-tuberculous mycobacterial diseases as outlined in the 2020 edition [12].

Positive NGS sequences, cultures, and pathological findings from clinical specimens are utilized for diagnosing infections caused by a range of pathogens, including viruses, Salmonella, Burkholderia, Staphylococcus aureus, Klebsiella pneumoniae, Candida, Aspergillus, and Cryptococcus.

Opportunistic infections are defined as infections that arise from bacteria, fungi, viruses, or commensal organisms which are part of the normal human microbiota and are typically non-pathogenic in individuals with intact immune systems. However, these organisms can become pathogenic and cause disease when the host's immune defenses are compromised.

Disseminated infection involved two or more non-adjacent organ systems, while limited infection affected only one.

Exacerbations are defined as episodes of clinical deterioration that necessitate hospitalization for therapeutic intervention, with each episode being recorded as a separate event.

In the infective phase, patients exhibited symptoms of infection, such as chills, fever, cough, sputum, skin, and soft tissue infections, with elevated infective indices. In the stable phase, patients’ initial infection was under control and symptoms improved.

The immune damage refers to elevated levels of AIGAs titer (1:2500), accompanied by increased immune indices, such as GLB, IgG, IgE, IgG4, eosinophil (Eos) and ESR, or non-infectious clinical manifestations such as rash, immune-related ocular disorders.

Clinical, laboratory, and outcome data

Clinical and laboratory data were collected at baseline, and patients were followed up for 36 months. Data on clinical processes and outcomes were collected at different times during the follow up visits.

Outcome categories for AIGAs-positive patients included: cured (no infection reappearance for ≥6 months post-treatment, negative AIGAs result in ELISA testing, and no confirmed neutralizing ability by WB), improvement (symptom amelioration post-treatment), exacerbation (symptoms that deteriorate following treatment may necessitate hospitalization for further management), and death. Exacerbation, progression-free survival (PFS), and overall survival (OS) were recorded during follow-up.

Detection of AIGAs

Indirect ELISA was used to qualitatively determine positive and negative AIGAs. Positive results were categorized into three titer using dilutions of 1:100, 1:500, and 1:2500.

WB analysis tested AIGAs neutralizing capacity in the STAT1 pathway. Thp1 cells were differentiated into adherent macrophages with Phorbol 12-myristate 13-acetate (PMA). Patients’ serum and IFN-γ created reaction conditions. Positive patients’ AIGAs inhibited STAT1 pathway, confirmed low p-STAT1 expression on Polyvinylidene Fluoride (PVDF). Normal and negative patients showed activated STAT1 pathway with noticeable p-STAT1 expression. ImageJ quantified protein signal intensity.

Statistical analysis

In group comparisons of normally distributed continuous data, t-tests or ANOVA are used. For non-normally distributed continuous data, Mann–Whitney U test is used for independent samples and Wilcoxon signed-rank test for related samples. Count data group comparisons use chi-square or Fisher’s test. Pearson correlation is used to analyse the relationship between changes in laboratory data and glucocorticoid dose.

The Kaplan-Meier method creates survival curves, the Log-rank test compares group differences, and the Cox proportional hazards regression model assesses factors impacting disease progression. K-means clustering categorizes patients with high AIGAs titer.

Statistical analysis and graph generation are done using SPSS (Version 27.0), R language (Version 4.0.2), and GraphPad Prism (Version 10). A two-tailed P value less than 0.05 is considered statistically significant.

Ethical approval and consent to participate

The study was reviewed and approved by the Ethics Committee of The First Affiliated Hospital of Guangxi Medical University (IRB Protocol Number: 2022-KT-Guike-127). All participants provided a signed written informed consent form.

Results

Demographic, clinical characteristics, and outcomes of participants

A total of 238 patients were enrolled in the study, consisting of 135 AIGAs-positive and 103 AIGAs-negative patients during the infective phase. Following the initial treatment, of the 135 AIGAs-positive patients, 131 showed improvement, 1 deteriorated and was subsequently discharged, and 3 died. Of these, 132 AIGAs-positive patients underwent follow-up to assess clinical outcomes and the frequency of exacerbations; during this period, 61 patients did not experience any exacerbations, 71 experienced exacerbations, 7 patients died, and 2 achieved complete remission. For the 103 AIGAs-negative patients post-treatment, 99 showed improvement and 3 died. Among the 99 AIGAs-negative patients who improved, 73 did not experience exacerbations, 26 experienced exacerbations, and 2 died during the follow-up period. Furthermore, 70 of the 135 AIGAs-positive patients were regularly monitored for AIGAs titer and immune indices at 1, 3, and 6 months post-initial treatment. Among these 70 patients, 55 received additional monitoring at 9 and 12 months. The study's flowchart is showed in Figure 1. Figure 1. The flowchart of the study.

AIGAs-positive patients included 60(44.4%) females and 75(55.6%) males, with an average age of 55.12 years. No significant differences were observed in sex, age, and body mass index (BMI) between AIGAs-positive and AIGAs-negative patients (Table 1). A lower proportion of AIGAs-positive patients had underlying health conditions, and a higher proportion of these patients resided in rural areas (Table 1). Among the 57 AIGAs-positive patients with these conditions, the prevalence was hypertension (53%), diabetes (18%), chronic hepatitis B (14%), chronic kidney disease (7%), and other chronic diseases (9%). The geographical distribution of AIGAs Syndrome in Guangxi, China is shown in Supplementary Figure 1. Table 1. Comparison of clinical information and laboratory data between AIGAs-positive and AIGAs-negative groups.

Variables	AIGAs-positive group
(n = 135)	AIGAs-negative group
(n = 103)	P value	
General characteristics	 	 	 	
Gender, male n (%)	75(55.6)	45(43.7)	0.07	
Average age (years)	55.12 ± 12.65	54.46 ± 15.97	0.73	
BMI (kg/m2)	21.63 ± 3.04	20.83 ± 3.66	0.079	
Underlying diseases, yes n (%)	57(42.2)	64(62.1)	0.002	
Residence, rural n (%)	95(70.4)	58(56.3)	0.025	
No. of infective pathogens	4[3–6]	4[2–5]	0.037	
Disseminated infection, yes n (%)	125(92.6)	55(53.4)	<0.001	
No. of exacerbations
Clinical manifestation, n (%)	1[0–2]	0[0–1]	<0.001	
Fever	91(67.4)	44(42.7)	<0.001	
Hepatosplenomegaly	22(16.3)	5(6.8)	<0.001	
Anemic appearance	40(29.6)	2(1.9)	<0.001	
Lung involvement	129(95.6)	102(99.0)	0.143*	
Lymph nodes involvement	118(87.4)	49(47.6)	<0.001	
Bone involvement	67(49.6)	5(4.9)	<0.001	
Skin involvement	32(23.7)	3(2.9)	<0.001	
Bloodstream infection
Laboratory data	29(21.5)	2(1.9)	<0.001	
WBC (x109cells/L)	14.23[9.80–19.06]	6.44[4.89–8.62]	<0.001	
Neu (x109cells/L)	10.66[6.78–15.90]	4.27[2.89–6.14]	<0.001	
Lym (x109cells/L)	1.86[1.16–2.49]	1.41[0.90–1.79]	<0.001	
Eos (x109cells/L)	0.32[0.13–0.67]	0.11[0.04–0.23]	<0.001	
Mon (x109cells/L)	0.77[0.56–1.10]	0.54[0.38–0.67]	<0.001	
HGB (g/L)	95.85 ± 23.22	115.61 ± 20.06	<0.001	
CRP (mg/L)	93.69[41.50–137.01]	7.91[1.52–49.50]	<0.001	
ESR (mm/h)	80.00[60.00–101.60]	25.00[10.00–53.20]	<0.001	
SF (μg/L)	782.34[360.44–1368.30]	282.22[111.91–423.15]	<0.001	
CD3+ T cells (%)	66.92 ± 12.79	71.08 ± 10.29	0.028	
CD4+ T cells (%)	35.63 ± 10.80	41.78 ± 7.51	<0.001	
CD8+ T cells (%)	28.54 ± 9.92	26.60 ± 9.47	0.205	
NK cells (%)	15.32[9.59–21.32]	13.66[6.79–16.91]	0.044	
B cells (%)	10.32[6.95–15.72]	13.75[8.01–17.58]	0.427	
IgG (g/L)	23.93 ± 9.30	14.64 ± 5.68	<0.001	
IgE (g/L)	209.10[64.10–519.75]	52.90[22.40–151.57]	<0.001	
IgG4 (g/L)	1.53[0.79–2.48]	1.08[0.62–1.58]	0.019	
GLB (g/L)	44.04 ± 10.34	31.78 ± 7.13	<0.001	
ALB (g/L)	31.20 ± 6.49	36.81 ± 6.54	<0.001	
CHE(U/L)	4255.00[3187.25–6615.50]	7387.00[5608.00–8812.00]	<0.001	
*Fisher exact probability.

The median pathogen numbers in the AIGAs-positive group were higher than AIGAs-negative group (P < 0.05, Table 1). Among AIGAs-positive patients, TM was the most common pathogen, followed by NTM (Supplementary Figure 2). Disseminated infection was observed in 92.6% of AIGAs-positive patients, higher than in the AIGAs-negative group. Symptoms such as fever, hepatosplenomegaly, anemia, and involvement of bone, lymph nodes, skin, and bloodstream infection were more common in AIGAs-positive patients (Table 1).

The AIGAs-positive group showed higher levels of white blood cell (WBC), neutrophil (Neu), lymphocyte (Lym), Eos, monocyte (Mon), ESR, C-reactive protein (CRP), serum ferritin (SF), GLB, IgG, IgE, and IgG4 compared with the AIGAs-negative group (P < 0.05). The AIGAs-positive group had lower levels of hemoglobin (HGB), albumin (ALB), and cholinesterase (CHE) than the AIGAs-negative group (P < 0.001, Table 1). The percentages of CD3+ T cells and CD4+ T cells were lower in the AIGAs-positive group, while percentages of natural killer (NK) cells were higher (Table 1).

The PFS of the AIGAs-positive group was 32.4% (95% CI: 21.23% – 43.57%), and the PFS of the AIGAs-negative group was 71.4% (95% CI: 61.21% – 81.59%). The AIGAs-positive group had a higher risk of aggravation compared to the AIGAs-negative group (HR, 2.602; 95% CI: 1.644–4.120), which was statistically significant (P < 0.001, Supplementary Figure 3A). The OS were 91.7% (95% CI: 86.2–97.2%) in the AIGAs-positive group and 93.9% (95% CI: 89.2% – 98.6%) in the AIGAs-negative group, with no significant difference in the risk of death between the two groups (P = 0.769, Supplementary Figure 3B).

The AIGAs-positive group had more exacerbations than the AIGAs-negative group (P < 0.001, Table 1 and Supplementary Figure 4). Monofactor Cox regression analysis identified 13 exacerbating risk factors and 2 protective factors (Supplementary Table 1). Multivariate Cox regression analysis demonstrated that night sweats, nausea, pleural involvement, and high Neu counts were risk factors for exacerbation, while a decrease in the AIGAs titer during the follow-up and anti-NTM treatment were protective factors (Supplementary Table 1).

Immunological characteristics of AIGAs syndrome

Of the 135 AIGAs-positive patients, we first compared the pertinent data of those with high and low AIGAs titer during the infective phase. The group with high AIGAs titer (1:2500) had higher frequencies of multiple pathogens and disseminated infections, with TM and NTM as the common pathogens than the group with low AIGAs titer (1:100 and 1:500; P < 0.05, Supplementary Table S2). The group with high AIGAs titer also had higher levels of WBC, Neu, Eos, ESR, CRP, GLB, IgG4, and percentage of NK cell (P < 0.05, Supplementary Table S2).

Subsequently, of the 135 AIGAs-positive patients, 70 were regularly monitored for AIGAs titer and immune indices at least six months. Laboratory data were compared between the infective and stable phases. The data on the stable phase were collected from within 1–3 months after discharge. The results showed a decrease in levels of WBC, Neu, Eos, ESR, CRP, GLB, IgG and IgE, as well as the percentage of the CD3+ T cells, CD4+ T cells, and CD8+ T cells, while the percentage of the NKT cells were higher in the stable phase (P < 0.05, Supplementary Table 3).

Moreover, of the 70 AIGAs-positive patients regularly monitored, it is noteworthy that some patients with high AIGAs titer still had elevated levels of IgG, IgE, Eos, ESR or exhibited clinical symptoms related to high levels of AIGAs titer despite effective infection management. This study utilized K-means (KM) clustering to group patients with high AIGAs titer based on Eos, IgG, IgE, ESR, and presence of symptoms. When K = 7, the curve tends to be flat, so K = 7 was used as the optimal value for k-means cluster analysis (Supplementary Figure 5).

Patients with high AIGAs titer were grouped into 7 groups based on IgG, IgE, Eos, ESR levels and symptoms. As shown in Supplementary Table 4, groups 1–6 showed elevated levels of immune damage markers, while group 7 had low levels of these markers and no immune-related symptoms. Therefore, these 70 patients can be categorized into three subtypes: Type I: low AIGAs titer without immune damage (12 cases), Type II: high AIGAs titer with immune damage (38 cases), and Type III: high AIGAs titer without immune damage (20 cases). Higher levels of IgG, IgE, and ESR were observed in patients with high AIGAs titer and immune damage compared to the other subtypes (Figure 2). Figure 2. Comparison of levels of Eos, ESR, IgG, and IgE in different subtypes of AIGAspositive patients during the stable phase, * indicates statistical significance compared to the High AIGAs titer with immune damage group, P < 0.05.

Of the 70 AIGAs-positive patients, 55 were assessed for AIGAs titer and immune indices at 0, 1, 3, 6, 9, and 12 months. 69.09% had decreased AIGAs titer and the levels of GLB, IgG, IgE, and IgG4 decreasing over time (Figures 3 and 4, Supplementary Figure 6). Figure 3. The proportional changes in different AIGAs titer in AIGAs-positive patients who used glucocorticoid and those who did not during the follow-up period.

Figure 4. The changes in the levels of GLB, IgG, IgG4, and IgE in AIGAs-positive patients who used glucocorticoid and those who did not during the follow-up period.

Glucocorticoid treatment of patients with high levels of AIGAs

Out of 86 AIGAs-positive patients, all received antibiotic therapy targeted at the specific pathogen, as well as treatment for underlying conditions such as diabetes and hypertension. AIGAs titer and laboratory data were detected during the infective phase and one month after discharge. A decrease in AIGAs titer was observed in 9 patients, while 77 patients did not. Of the 9 patients with a decrease in AIGAs titer, 8 (88.9%) were treated with glucocorticoids. However, only 26 (33.8%) of the 77 patients without a decrease in AIGAs titer received glucocorticoid treatment (P = 0.002) (Supplementary Table 5).

Of the 34 AIGAs-positive patients treated with glucocorticoids, 8 showed a decrease in AIGAs titer, while 26 did not. The clinical information and laboratory data between these two groups were compared and no statistically significant differences were observed (see Supplementary Table 6 for details). Supplementary Figure 7 illustrated that the cumulative glucocorticoid dose was higher in the group with decreased AIGAs titer (P = 0.001). The dose of glucocorticoid was converted to prednisone acetate equivalent doses. The prednisone acetate dose in the decreased AIGAs titer group was 378.5 [264.8–738.8] mg, compared to 161.5 [102.5–243.8] mg in the non-decreased AIGAs titer group (P = 0.001). Correlation analysis revealed a positive relationship between decreases in IgG4 levels (r = 0.774, P = 0.024) and CRP levels (r = 0.832, P = 0.01) after treatment with glucocorticoid dose (Supplementary Table 7).

As previously mentioned, 31 patients in the stable phase with high AIGAs titer were treated with low-dose glucocorticoids. Before treatment, 20 patients had elevated IgG levels, 15 had increased IgE levels, 10 had elevated IgG4 levels, 23 had high ESR levels, 6 had increased Neu levels, 2 had high eosinophil levels, 4 had a rash, 4 experienced fatigue and loss of appetite, 1 had ocular immune damage, and 1 had pericardial effusion. During follow-up after glucocorticoid treatment, 67.74% of patients showed a decrease in AIGAs titer, along with significant reductions in IgG, IgE, IgG4, ESR, and eosinophil levels (P < 0.05, Table 2), as well as improvements in symptoms. Table 2. Comparison of laboratory data before and after glucocorticoid treatment of AIGAs-positive patients with high AIGAs titer and increased immune damage in the stable phase.

Variables	Before glucocorticoid treatment	After glucocorticoid treatment	P value	
WBC(×109/L)	10.60[6.49–13.66]	9.11[6.95–10.53]	0.065	
Neu(×109/L)	6.85[3.70–9.72]	5.52[4.23–7.54]	0.064	
Lym(×109/L)	2.04[1.65–2.69]	2.29[1.46–3.01]	0.572	
Eos(×109/L)	0.22[0.12–0.51]	0.14[0.09–0.37]	0.013	
Mon(×109/L)	0.61[0.50–0.81]	0.61[0.47–0.79]	0.673	
CRP (mg/L)	14.26[10.20–51.34]	10.66[6.72–29.70]	0.003	
ESR(mm/h)	52.50[33.75–84.00]	29.75[14.88–59.92]	<0.001	
IgG(g/L)	19.85[13.7–22.65]	15.17[11.82–19.85]	0.014	
IgA(g/L)	2.18[1.77–2.88]	1.89[1.57–2.53]	0.047	
IgM(g/L)	1.33[0.79–1.84]	1.36[0.89–1.84]	0.433	
IgE(g/L)	174.75[73.40–591.10]	113.10[54.32–263.06]	0.002	
IgG4(g/L)	1.77[1.02–3.36]	1.35[0.62–2.48]	0.009	
GLB(g/L)	41.62 ± 12.12	35.15 ± 8.06	<0.001	

Of the 55 AIGAs-positive patients monitored over a 12-month period, 30 received glucocorticoid treatment at stable phase, while 25 did not. Both treatment groups showed a decrease in AIGAs titer and immune indices (Figures 3 and 4). Analysis of initial data revealed that patients received glucocorticoid had higher levels of IgE (349.4[118.9–624.75]) and GLB (42.6 [35.95–51.65]) compared to those not receiving glucocorticoid treatment (80.1[40.98–351.88] and 35.50[30.80–46.45]) (P < 0.05). These findings suggest that AIGAs titer decrease when the infection is under control, and glucocorticoid treatment can reduce inflammatory markers, alleviating discomfort in patients with an immune damage.

Discussion

This 3-year prospective study is currently the largest sample size study aimed at investigating the immunological characteristics and outcomes of AIGAs syndrome. Patients with AIGAs syndrome showed elevated levels of GLB, IgG, IgG4, IgE, ESR, and eosinophils. Over the course of the study, AIGAs titer and levels of GLB, IgG, IgG4, and IgE decreased in most patients. Three major subtypes of AIGA syndrome were identified during stable phase, and individuals with high AIGAs titer and immune damage may benefit from glucocorticoid treatment. Glucocorticoid treatment reduced levels of immune indices and improved symptoms, highlighting the immunological characteristics of AIGAs syndrome. The study offers valuable insights into the immune abnormalities associated with AIGAs syndrome and identifies subtypes that could guide targeted therapeutic approaches.

Disseminated opportunistic infections are often the key initial clue for diagnosing AIGAs-positive patients. Previous studies have shown that in areas like Thailand, Hong Kong, and Taiwan, over 80% of patients with disseminated NTM infections have been identified as AIGAs-positive, with the predominant pathogens being NTM and TM [1,13]. Our finding shown that 92.6% of AIGAs-positive patients had disseminated infections of multiple pathogens. Despite receiving appropriate antibiotics, 52.6% of patients still experienced exacerbations, possibly due to the high levels of AIGAs. However, detailed information on the changes in AIGAs titer and the direct damage to patients associated with AIGAs has been rarely reported.

AIGAs are B cell-derived IgG antibodies, predominantly IgG1 and IgG4 subtypes [1,14], it was found elevated levels of IgG, IgE, and IgG4 were reported in patients [1], similar with our research. The increases in globulins and IgG are likely attributable to AIGAs, while the IgG4 elevation may indicate the presence of the IgG4 AIGAs subtype. In some studies, AIGAs-positive patients have shown immunological damage to the skin and eyes, which is thought to be related to elevated AIGAs titer [15,16]. A decrease in AIGAs concentration has been linked to improvements in skin and ocular damage [16].

This study reports a novel finding of elevated eosinophil counts and IgE levels in patients with AIGAs syndrome, suggesting an allergic or inflammatory response. Typically undetectable or present at minimal levels in serum under normal physiological conditions, increased IgE, secreted by B cells, plays a key role in mediating allergic responses, infection, and other immune responses [17]. Previous studies have shown that elevated levels of autoreactive IgE are present in certain autoimmune diseases such as systemic lupus erythematosus (SLE) and are associated with the overproduction of autoantibodies [18,19]. Eosinophils, integral to allergic inflammation, are activated by the Th2 cytokine IL-5, leading to the release of inflammatory mediators and participation in immune responses [20]. Th2 inflammatory response activated after pathogen infection further stimulates B cells and plasma cells to produce large amounts of IgE and activates eosinophils; the increased eosinophils and B cells can interact with each other, together promoting an allergic immune response [21]. Therefore, in AIGAs-positive patients, T cells, B cells, and their intercellular interactions are collectively implicated in the immunopathogenesis of the disease.

For patients with AIGAs syndrome in our study, they are categorized into acute and stable phases. During the acute phase, the majority of patients exhibit high AIGAs titer and elevated IgG levels. In the stable phase, while most patients experience a decrease in AIGAs titer and IgG levels, a subset of patients shows persistent elevation or a subsequent rise after an initial decrease in these indicators. The levels of AIGAs and IgG undergo dynamic changes throughout the disease's progression. Based on these observations, in the stable phase of AIGAs syndrome, three subtypes have been identified: Type I, characterized by a low AIGAs titer and no immune damage; Type II, with a high AIGAs titer but no immune damage; and Type III, which presents a high AIGAs titer and associated immune damage. Patients with a high AIGAs titer and associated immune damage exhibit elevated levels of IgG and IgE, indicative of active B cell activity and an ongoing humoral immune response, which may be closely related to the increased titer of AIGAs. Whether there is a transformation between subtypes over time requires further investigation with a larger sample size and longer-term follow-up to observe changes in AIGAs titer and immune indices.

Our results indicated that lower levels of AIGAs are associated with a reduced risk of disease recurrence, which often manifests as an exacerbation of infections. This also suggests that low levels of AIGAs predict a lower risk of infection, while high levels of AIGAs predict a higher risk of infection. Type III patients with high AIGAs titer accompanied by immune damage require interventional treatment; glucocorticoids were chosen to mitigate the immune damage and alleviate discomfort. After an average of 2–3 months of glucocorticoid therapy, patients’ symptoms improved, and levels of globulins, IgG, IgE, ESR, and eosinophils decreased, with most patients experiencing a reduction in AIGAs titer. However, approximately 40% of AIGAs-positive patients experienced an increase in AIGAs titer and a recurrence of inflammatory markers upon discontinuation of glucocorticoid treatment, indicating the need for extended glucocorticoid treatment.

AIGAs syndrome was first recognized in 2004 [22]. Currently, there is no standard treatment available. Various immunomodulatory agents have been tried, such as rituximab, daratumumab, and cyclophosphamide [9,10,23–25]. However, these studies are limited to case reports and small sample sizes, with no follow-up monitoring of AIGAs. Moreover, patients are still prone to relapse and worsening during disease progression.

Glucocorticoids regulate T cell distribution and response, contributing to the maintenance of T cell populations and effective immune protection against infection [26,27]. They reduce B cell counts, inhibit early B cell proliferation, and decrease IgG production [28,29]. Therefore, glucocorticoids are widely used to treat allergies, autoimmunity, and chronic inflammation. However, their effects on AIGAs-positive patients are rarely reported. Our results show that glucocorticoids are effective for this disease in both the acute and stable phases. Although the specific mechanism by which glucocorticoids decrease AIGAs levels remains unknown, glucocorticoid treatment is an effective therapeutic option for patients with high levels of AIGAs accompanied by immune damage. Further research is needed to determine the appropriate duration and regimen for AIGAs-positive patients.

This study encountered several limitations. First, the number of AIGAs-positive patients available for follow up and the analysis of AIGAs titer were limited. Second, the sample size of patients treated with glucocorticoid was small, which might lead to selection bias. Third, this research was conducted in a single centre, so further studies are needed to extrapolate the findings to other endemic regions.

Conclusions

AIGAs-positive patients exhibit distinct immunological characteristics. Elevated levels of AIGAs, IgG, IgE, ESR, and eosinophils suggest a state of immune damage, indicating a high risk for infection and disease exacerbation. During stable phases, patients can be categorized into three subtypes, with Type III potentially requiring interventional treatment. Glucocorticoid therapy effectively reduces these indices and improves disease conditions. Further research is essential to fully understand the immunological mechanisms underlying AIGAs syndrome and to enhance treatment strategies for affected patients.

Supplementary Material

Ethical Approval.pdf

Supplementary_Tables_and_Supplementary_Figures_revise.pdf

Author contribution

Zhiyi He designed the study and had full responsibility for the facticity of data. Rong Xiao, Ni Chen, Xiaona Liang, and Pei Li conducted the experiments. Zengtao Luo, Quanfang Chen, Jingmin Deng, Meihua Li, Meiling Yang, Wen Zeng, Haijuan Tang, Shouming Qin, Siyao Wu, Yan Ning, Jing Jiang, Ke Wang, Xinxin Zhong, Fu Cao, Zhen Wei, Jiujin Zhang, Qing Wei, Jie Huang and Chengqiong Xu collected clinical data and contributed to the follow up of patients. Siqiao Liang, Hanlin Liang, and Xuemei Huang performed statistical analyses and contributed to writing of the manuscript. Hongwei Wang, Honglin Luo, Jian Song, Xiaokai Feng, Chenlu Yang, Jieping Lei and Bin Cao revised the manuscript. All authors read and approved the final manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The information provided herein has not been previously presented at any meetings. All data are available from the corresponding authors upon reasonable request.
==== Refs
References

1 Browne SK, Burbelo PD, Chetchotisakd P, et al. Adult-onset immunodeficiency in Thailand and Taiwan. N Engl J Med. 2012;367 (8 ):725–734. doi:10.1056/NEJMoa1111160 22913682
2 Höflich C, Sabat R, Rosseau S, et al. Naturally occurring anti–IFN-γ autoantibody and severe infections with Mycobacterium cheloneae and Burkholderia cocovenenans. Blood. 2004;103 (2 ):673–675. doi:10.1182/blood-2003-04-1065 12947000
3 Guo J, Ning XQ, Ding JY, et al. Anti-IFN-γ autoantibodies underlie disseminated Talaromyces marneffei infections. J Exp Med. 2020;217 (12 ):e20190502.
4 Aoki A, Sakagami T, Yoshizawa K, et al. Clinical significance of interferon-γ neutralizing autoantibodies against disseminated nontuberculous mycobacterial disease. Clin Infect Dis. 2018;66 (8 ):1239–1245. doi:10.1093/cid/cix996 29126235
5 Liang X, Si L, Li Y, et al. Talaromyces marneffei infection relapse presenting as osteolytic destruction followed by suspected nontuberculous mycobacterium infection during 6 years of follow-up: a case update. Int J Infect Dis. 2020;93 :208–210. doi:10.1016/j.ijid.2020.02.037 32105768
6 Wu UI, Holland SM. Host susceptibility to non-tuberculous mycobacterial infections. Lancet Infect Dis. 2015;15 (8 ):968–980. doi:10.1016/S1473-3099(15)00089-4 26049967
7 Wu UI, Holland SM. A genetic perspective on granulomatous diseases with an emphasis on mycobacterial infections. Semin Immunopathol. 2016;38 (2 ):199–212. doi:10.1007/s00281-015-0552-y 26733044
8 Yu Q, Wei M, Xiao R, et al. Clinical characteristics, course, and long-term outcomes in patients with Talaromyces marneffei infection: a 10-year retrospective cohort study. Infect Dis Ther. 2023;12 (5 ):1283–1297. doi:10.1007/s40121-023-00801-5 37055706
9 Czaja CA, Merkel PA, Chan ED, et al. Rituximab as successful adjunct treatment in a patient with disseminated nontuberculous mycobacterial infection due to acquired anti-interferon-γ autoantibody. Clin Infect Dis. 2014;58 (6 ):e115–e118. doi:10.1093/cid/cit809 24336756
10 Hong GH, Ortega-Villa AM, Hunsberger S, et al. Natural history and evolution of anti-interferon-γ autoantibody-associated immunodeficiency syndrome in Thailand and the United States. Clin Infect Dis. 2020;71 (1 ):53–62. doi:10.1093/cid/ciz786 31429907
11 Chen YC, Weng SW, Ding JY, et al. Clinicopathological manifestations and immune phenotypes in adult-onset immunodeficiency with anti-interferon-γ autoantibodies. J Clin Immunol. 2022;42 (3 ):672–683. doi:10.1007/s10875-022-01210-y 35089479
12 Kurz SG, Zha BS, Herman DD, et al. Summary for clinicians: 2020 clinical practice guideline summary for the treatment of nontuberculous mycobacterial pulmonary disease. Ann Am Thorac Soc. 2020;17 (9 ):1033–1039. doi:10.1513/AnnalsATS.202003-222CME 32870060
13 Valour F, Perpoint T, Sénéchal A, et al. Interferon-γ autoantibodies as predisposing factor for nontuberculous mycobacterial infection. Emerg Infect Dis. 2016;22 (6 ):1124–1126. doi:10.3201/eid2206.151860 27192204
14 Wipasa J, Chaiwarith R, Chawansuntati K, et al. Characterization of anti-interferon-γ antibodies in HIV-negative immunodeficient patients infected with unusual intracellular microorganisms. Exp Biol Med (Maywood). 2018;243 (7 ):621–626.29512397
15 Su SS, Zhang SN, Ye JR, et al. Disseminated Talaromyces marneffei and mycobacterium avium infection accompanied sweet's syndrome in a patient with anti-interferon-γ autoantibodies: a case report. Infect Drug Resist. 2019;12 :3189–3195. doi:10.2147/IDR.S218836 31632104
16 Ning Y, Yu Q, Liang H, et al. Multiple intracellular pathogen infections with ocular pathologies associated with adult-onset immunodeficiency due to anti-interferon-γ autoantibodies: a case report. BMC Infect Dis 2024;24 (1 ):78, doi:10.1186/s12879-024-09003-x 38216890
17 Kelly BT, Grayson MH. Immunoglobulin E, what is it good for? Ann Allergy Asthma Immunol. 2016;116 (3 ):183–187. doi:10.1016/j.anai.2015.10.026 26945494
18 Augusto J-F, Truchetet M-E, Charles N, et al. IgE in lupus pathogenesis: friends or foes? Autoimmun Rev. 2018;17 (4 ):361–365. doi:10.1016/j.autrev.2017.11.027 29425937
19 Henault J, Riggs JM, Karnell JL, et al. Self-reactive IgE exacerbates interferon responses associated with autoimmunity. Nat Immunol 2016;17 (2 ):196–203. doi:10.1038/ni.3326 26692173
20 Stone KD, Prussin C, Metcalfe DD. Eosinophilic gastrointestinal disease and peanut allergy are alternatively associated with IL-5+ and IL-5- Th2 responses. J Allergy Clin Immunol. 2010;125 (2 ):AB124–ABS80. doi:10.1016/j.jaci.2009.12.488
21 Gevaert P, Wong K, Millette LA, et al. The role of IgE in upper and lower airway disease: more than just allergy! Clin Rev Allergy Immunol. 2022;62(1):200–215.
22 Döffinger R, Helbert MR, Barcenas-Morales G, et al. Autoantibodies to interferon-gamma in a patient with selective susceptibility to mycobacterial infection and organ-specific autoimmunity. Clin Infect Dis. 2004;38 (1 ):10–16. doi:10.1086/380454 14679442
23 Browne SK, Zaman R, Sampaio EP, et al. Anti-CD20 (rituximab) therapy for anti-IFN-γ autoantibody-associated nontuberculous mycobacterial infection. Blood. 2012;119 (17 ):3933–3939. doi:10.1182/blood-2011-12-395707 22403254
24 Koizumi Y, Sakagami T, Nishiyama N, et al. Rituximab restores IFN-γ-STAT1 function and ameliorates disseminated mycobacterium avium infection in a patient with anti-interferon-γ autoantibody. J Clin Immunol. 2017;37 (7 ):644–649. doi:10.1007/s10875-017-0425-3 28779413
25 Angkasekiwinai N, Suputtamongkol Y, Tantibhedhyangkul W, et al. Efficacy of bortezomib for treating anti-interferon-gamma autoantibody-associated adult-onset immunodeficiency (AOID) syndrome. Clin Infect Dis. 2024;78(4):1033–1042.
26 Dimitrov S, Benedict C, Heutling D, et al. Cortisol and epinephrine control opposing circadian rhythms in T cell subsets. Blood. 2009;113 (21 ):5134–5143. doi:10.1182/blood-2008-11-190769 19293427
27 Taves MD, Ashwell JD. Glucocorticoids in T cell development, differentiation and function. Nat Rev Immunol. 2021;21 (4 ):233–243. doi:10.1038/s41577-020-00464-0 33149283
28 Cupps TR, Gerrard TL, Falkoff RJ, et al. Effects of in vitro corticosteroids on B cell activation, proliferation, and differentiation. J Clin Invest. 1985;75 (2 ):754–761. doi:10.1172/JCI111757 3871795
29 Xu Y, Jiang K, Chen F, et al. Bone marrow-derived naïve B lymphocytes improve heart function after myocardial infarction: a novel cardioprotective mechanism for empagliflozin. Basic Res Cardiol. 2022;117 (1 ):47. doi:10.1007/s00395-022-00956-1 36171393
