Diagnostic and Predictive Contribution of Autoantibodies Screening in a Large Series of Patients With Primary Immunodeficiencies

Flow cytometry-based diagnostic approach for inborn errors of immunity: experience from Algeria

Purpose

In this study, we retrospectively reviewed the use of flow cytometry (FCM) in the diagnosis of inborn errors of immunity (IEIs) at a single center in Algeria. Sharing insights into our practical experience, we present FCM based diagnostic approaches adapted to different clinical scenarios.

Methods

Between May 2017 and February 2024, pediatric and adult patients presenting with clinical features suggestive of immunodeficiency were subjected to FCM evaluation, including lymphocyte subset analysis, detection of specific surface or intracellular proteins, and functional analysis of immune cells.

Results

Over a nearly seven-year period, our laboratory diagnosed a total of 670 patients (372 (55.5%) males and 298 (44.5%) females), distributed into 70 different IEIs belonging to 9 different categories of the International Union of Immunological Societies classification. FCM was used to diagnose and categorize IEI in 514 patients (76.7%). It provided direct diagnostic insights for IEIs such as severe combined immunodeficiency, Omenn syndrome, MHC class II deficiency, familial hemophagocytic lymphohistiocytosis, and CD55 deficiency. For certain IEIs, including hyper-IgE syndrome, STAT1-gain of function, autoimmune lymphoproliferative syndrome, and activated PI3K delta syndrome, FCM offered suggestive evidence, necessitating subsequent genetic testing for confirmation. Protein expression and functional assays played a crucial role in establishing definitive diagnoses for various disorders. To setup such diagnostic assays at high and reproducible quality, high level of expertise is required; in house reference values need to be determined and the parallel testing of healthy controls is highly recommended.

Conclusion

Flow cytometry has emerged as a highly valuable and cost-effective tool for diagnosing and studying most IEIs, particularly in low-income countries where access to genetic testing can be limited. FCM analysis could provide direct diagnostic insights for most common IEIs, offer clues to the underlying genetic defects, and/or aid in narrowing the list of putative genes to be analyzed.

Antinuclear antibody-associated autoimmune cytopenia in childhood is a risk factor for systemic lupus erythematosus

ABSTRACT

Autoimmune cytopenia (AIC) in children may be associated with positive antinuclear antibodies (ANA) and may progress to systemic lupus erythematosus (SLE). We evaluated the risk of progression to SLE of childhood-onset ANA-associated AIC. In the French national prospective OBS'CEREVANCE cohort, the long-term outcome of children with ANA-associated AIC (ANA titer ≥1/160) and a subgroup of children who developed SLE were described. ANA were positive in 355 of 1803 (20%) children with AIC. With a median follow-up of 5.8 (range, 0.1-29.6) years, 79 of 355 (22%) patients developed SLE at a median age of 14.5 (1.1-21.4) years; 20% of chronic immune thrombocytopenic purpura, 19% of autoimmune hemolytic anemia, and 45% of Evans syndrome. None of the patients with ANA-negative test developed SLE. Severe manifestations of SLE were observed in 21 patients, and 2 patients died. In multivariate analysis including patients with positive ANA within the first 3 months after AIC diagnosis, age >10 years at AIC diagnosis (relative risk [RR], 3.67; 95% confidence interval [CI], 1.18-11.4; P = .024) and ANA titer >1/160 (RR, 5.28; 95% CI, 1.20-23.17; P = .027) were associated with the occurrence of SLE after AIC diagnosis. ANA-associated AIC is a risk factor for progression to SLE, especially in children with an initial ANA titer >1/160 and an age >10 years at AIC diagnosis. ANA screening should be recommended in children with AIC, and patients with ANA should be monitored long-term for SLE, with special attention to the transition period. This trial was registered at www.ClinicalTrials.gov as #NCT05937828.

Multilayer concept of autoimmune mechanisms and manifestations in inborn errors of immunity: Relevance for precision therapy

Autoimmunity in inborn errors of immunity (IEIs) has a multifactorial pathogenesis and develops subsequent to a genetic predisposition in conjunction with gene regulation, environmental modifiers, and infectious triggers. On the basis of incremental data availability owing to upfront application of omics technologies, a more granular and dynamic view of mechanisms and manifestations is warranted. Here, we present a comprehensive novel concept of autoimmunity in IEIs that considers multiple layers of interdependent elements and connects 101 causative genes or deletions according to the quality of the allelic variants with 47 molecular pathways and 22 immune effector mechanisms. Furthermore, we list 50 resulting manifestations together with the corresponding Human Phenotype Ontology terms and review the types and frequencies of the most relevant clinical presentations. When all of its elements are taken together, this concept (1) extends the historical anatomic view of central versus peripheral tolerance toward multiple interdependent mechanisms of immune tolerance, (2) delineates the mechanisms underlying the protean clinical manifestations, and thereby, (3) points toward the most suitable precision therapy for autoimmunity in IEIs. The multilayer concept of autoimmune mechanisms and manifestations in IEIs will facilitate research design and provide clinical guidance on the use of precision medicine irrespective of the data depth available in each health care scenario.

Assessment of autoantibodies in paediatric population with primary immunodeficiencies: a pilot study

BACKGROUND

The correlation between primary immunodeficiencies (PIDs) and autoimmunity shows ethnic and geographical diversity. The aim of our study was to accumulate more data in paediatric PID population.

METHODS

58 children aged 1-17 and with PID (study group) and 14 age-matched immunocompetent individuals (control group) were included in the study. Serum levels of 17 different specific IgG antibodies against autoantigens were measured by means of a quantitative enzyme immunoassay. Immunoglobulin levels were analysed in relation to a detailed medical examination.

RESULTS

Autoantibodies against one or more antigens were detected in the sera of 24.14% (n = 14) subjects in the study group. The most frequent were anti-thyroid peroxidase (anti-TPO) antibodies (n = 8; 13.8%). Anti-TPO antibody levels were elevated more often in PID patients with a positive family history of autoimmune diseases (p = 0.04). The screening for anti-deamidated gliadin peptide (DGP) and anti-tissue transglutaminase (tTG) antibodies in our series allowed identifying two previously undiagnosed cases of coeliac disease in PID patients. There was no statistically significant difference between the study and the control group in terms of the autoantibodies prevalence.

CONCLUSIONS

This study provides data on the prevalence of autoantibodies in paediatric population diagnosed with PID. Selected autoantibodies (i.e. anti-tTG, anti-DGP) might be useful for the screening of PID to avoid the delay of diagnosis of an autoimmune disease.

Clinical, immunological, molecular and therapeutic findings in monogenic immune dysregulation diseases: Middle East and North Africa registry

Monogenic immune dysregulation diseases (MIDD) are caused by defective immunotolerance. This study was designed to increase knowledge on the prevalence and spectrum of MIDDs, genetic patterns, and outcomes in Middle East and North Africa (MENA). MIDD patients from 11 MENA countries (Iran, Turkey, Kuwait, Oman, Algeria, Egypt, United Arab Emirates, Tunisia, Jordan, Qatar, and Azerbaijan) were retrospectively evaluated. 343 MIDD patients (58% males and 42% female) at a median (IQR) age of 101 (42-192) months were enrolled. The most common defective genes were LRBA (23.9%), LYST (8.2%), and RAB27A (7.9%). The most prevalent initial and overall manifestations were infections (32.2% and 75.1%), autoimmunity (18.6% and 41%), and organomegaly (13.3% and 53.8%), respectively. Treatments included immunoglobulin replacement therapy (53%), hematopoietic stem cell transplantation (HSCT) (14.3%), immunosuppressives (36.7%), and surgery (3.5%). Twenty-nine (59.2%) patients survived HSCT. Along with infectious complications, autoimmunity and organomegaly may be the initial or predominant manifestations of MIDD.

Diagnostic Challenges in Patients with Inborn Errors of Immunity with Different Manifestations of Immune Dysregulation

Inborn errors of immunity (IEI), formerly known as primary immunodeficiency disorders (PIDs), are inherited disorders caused by damaging germline variants in single genes, which result in increased susceptibility to infections and in allergic, autoimmune, autoinflammatory, nonmalignant lymphoproliferative, and neoplastic conditions. Along with well-known warning signs of PID, attention should be paid to signs of immune dysregulation, which seem to be equally important to susceptibility to infection in defining IEI. The modern diagnostics of IEI offer a variety of approaches but with some problems. The aim of this review is to discuss the diagnostic challenges in IEI patients in the context of an immune dysregulation background.

Algerian Registry for Inborn Errors of Immunity in Children: Report of 887 Children (1985-2021)

INTRODUCTION

Inborn errors of immunity (IEI) represent a heterogeneous large group of genetic disorders characterized by susceptibility of affected individuals to recurrent infections, autoimmune/inflammatory diseases, allergy, and malignancy. We aimed to report for the first time the Algerian registry for IEI in children.

METHODS

We described the characteristics of IEI in Algerian children from the data collected in the Algerian registry for IEI between 1985 and 2021.

RESULTS

Over a period of 37 years, we included 887 children (530 male, 59.6%) with a mean age at diagnosis of 3.23 years and a mean diagnosis delay of 2 years. The prevalence rate was estimated at 1.97/100,000 inhabitants or 5.91/100,000 children. The parental consanguinity was found in 52.6%. The most prevalent category was combined immunodeficiencies (CID) (35.5%), followed by predominantly antibody deficiencies (24.5%) and CID with syndromic features (18.3%). The most predominant diseases were severe CID (134 cases), MHC II deficiency (99 cases), agammaglobulinemia (82 cases), common variable immunodeficiency (78 cases), hyper IgE syndromes (61 patients), ataxia-telangiectasia (46 patients), Wiskott-Aldrich syndrome (40 patients) and chronic granulomatous disease (39 cases). The clinical presentation was dominated by lower respiratory tract infections (69%), failure to thrive (38.3%), and chronic diarrhea (35.2%). Genetic analysis was performed in 156 patients (17.6%). The global mortality rate was 28.4% mainly caused by CID.

CONCLUSION

This is the first report of the Algerian registry for IEI in children. Data is globally similar to that of the Middle East and North African (MENA) registries with high consanguinity, predominance of CID, and significant mortality. This registry highlights the weak points that should be improved in order to provide better patient care.