A phenotypic approach for IUIS PID classification and diagnosis: guidelines for clinicians at the bedside

Too much of a good thing: a review of primary immune regulatory disorders

Primary immune regulatory disorders (PIRDs) are inborn errors of immunity caused by a loss in the regulatory mechanism of the inflammatory or immune response, leading to impaired immunological tolerance or an exuberant inflammatory response to various stimuli due to loss or gain of function mutations. Whilst PIRDs may feature susceptibility to recurrent, severe, or opportunistic infection in their phenotype, this group of syndromes has broadened the spectrum of disease caused by defects in immunity-related genes to include autoimmunity, autoinflammation, lymphoproliferation, malignancy, and allergy; increasing focus on PIRDs has thus redefined the classical 'primary immunodeficiency' as one aspect of an overarching group of inborn errors of immunity. The growing number of genetic defects associated with PIRDs has expanded our understanding of immune tolerance mechanisms and prompted identification of molecular targets for therapy. However, PIRDs remain difficult to recognize due to incomplete penetrance of their diverse phenotype, which may cross organ systems and present to multiple clinical specialists prior to review by an immunologist. Control of immune dysregulation with immunosuppressive therapies must be balanced against the enhanced infective risk posed by the underlying defect and accumulated end-organ damage, posing a challenge to clinicians. Whilst allogeneic hematopoietic stem cell transplantation may correct the underlying immune defect, identification of appropriate patients and timing of transplant is difficult. The relatively recent description of many PIRDs and rarity of individual genetic entities that comprise this group means data on natural history, clinical progression, and treatment are limited, and so international collaboration will be needed to better delineate phenotypes and the impact of existing and potential therapies. This review explores pathophysiology, clinical features, current therapeutic strategies for PIRDs including cellular platforms, and future directions for research.

Impact of Genetic Diagnosis on the Outcome of Hematopoietic Stem Cell Transplant in Primary Immunodeficiency Disorders

To evaluate the relationship between knowledge of genetic diagnosis before HSCT and outcome, we reviewed all HSCTs for primary immune deficiencies (PID) performed at UCSF from 2007 through 2018. SCID, a distinct entity identified since 2010 in California by newborn screening and treated early, was considered separately. The underlying genetic condition was known at the time of HSCT in 85% of cases. Graft failure was less frequent in patients with a genetic diagnosis (19% with a genetic diagnosis versus 47% without, p = 0.020). Furthermore, event-free survival and overall survival (OS) at 5 years were better for those with a genetic diagnosis (78% with versus 44% without, p = 0.006; and 93% versus 60% without, p = 0.0002, respectively). OS at 5 years was superior for known-genotype patients with both SCID (p = 0.010) and non-SCID PID (p = 0.010). There was no difference in OS between HSCT done in 2007-2010 compared to more recently (p = 0.19). These data suggest that outcomes of HSCT for PID with known genotype may reflect specific experience and literature, or that a substantial proportion of patients with PID of undetermined genotype may have had underlying conditions for which HSCT may carry greater risk. The higher rate of graft failure in PID with unknown genotype may be in part explained by insufficient conditioning, which in turn could be dictated by compromised organ function in patients undergoing HSCT late in the course. Widespread availability of PID gene sequencing as standard care can provide genetic diagnoses for most patients with PID prior to HSCT, permitting optimization of transplant approach.

Investigation of primary immune deficiency after severe bacterial infection in children: A population-based study in western France

BACKGROUND

Infectious diseases are still an important cause of morbidity and mortality in high-income countries and may preferentially affect predisposed children, especially immunocompromised children. We aimed to evaluate the frequency of recommended immunological tests in children with community-onset severe bacterial infection (COSBI) admitted to a pediatric intensive care unit. We also assessed the frequency and described the typology of diagnosed primary immune deficiency (PID).

METHODS

We conducted a retrospective observational epidemiological study in six university hospitals in western France. All children from 1 month to 16 years of age admitted to hospital for bacterial meningitis, purpura fulminans, or meningococcal disease between August 2009 and January 2014 were included. We analyzed the frequency, type, and results of the immunological tests performed on children with meningitis, purpura fulminans, or a meningococcemia episode.

RESULTS

Among the 143 children included (144 episodes), 84 (59%) and 60 (41%) had bacterial meningitis and purpura fulminans or meningococcemia, respectively: 72 (50%) had immunological tests and 8% had a complete immunological investigation as recommended. Among the 72 children examined for PID, 11 (15%) had at least one anomaly in the immunological test results. Two children had a diagnosis of PID (one with C2 deficit and the other with C8 deficit) and seven other children had possible PID. Thus, the prevalence of a definite or possible diagnosis of PID was 12% among the children examined.

CONCLUSION

PID is rarely investigated after COSBI. We raise awareness of the need for immunological investigations after a severe infection requiring PICU admission.

Pulmonary Manifestations of Immunodeficiency and Immunosuppressive Diseases Other than Human Immunodeficiency Virus

Immune deficiencies may alter normal lung function and protective mechanisms, resulting in a myriad of pulmonary manifestations. Primary immunodeficiencies involve multiple branches of the immune system, and defects may predispose to recurrent upper and lower respiratory infections by common pathogens; opportunistic infections; and autoimmune, inflammatory, and malignant processes that may result in interstitial pneumonias. Secondary immunodeficiencies may result from neoplasms or their treatment, organ transplant and immunosuppression, and from autoimmune diseases and their treatments. Primary and secondary immunodeficiencies and their pulmonary manifestations may be difficult to diagnose and treat. A multidisciplinary approach to evaluation is essential.

Immunoglobulin Replacement Therapy Versus Antibiotic Prophylaxis as Treatment for Incomplete Primary Antibody Deficiency

Background

Patients with an IgG subclass deficiency (IgSD) ± specific polysaccharide antibody deficiency (SPAD) often present with recurrent infections. Previous retrospective studies have shown that prophylactic antibiotics (PA) and immunoglobulin replacement therapy (IRT) can both be effective in preventing these infections; however, this has not been confirmed in a prospective study.

Objective

To compare the efficacy of PA and IRT in a randomized crossover trial.

Methods

A total of 64 patients (55 adults and 9 children) were randomized (2:2) between two treatment arms. Treatment arm A began with 12 months of PA, and treatment arm B began with 12 months of IRT. After a 3-month bridging period with cotrimoxazole, the treatment was switched to 12 months of IRT and PA, respectively. The efficacy (measured by the incidence of infections) and proportion of related adverse events in the two arms were compared.

Results

The overall efficacy of the two regimens did not differ (p = 0.58, two-sided Wilcoxon signed-rank test). A smaller proportion of patients suffered a related adverse event while using PA (26.8% vs. 60.3%, p < 0.0003, chi-squared test). Patients with persistent infections while using PA suffered fewer infections per year after switching to IRT (2.63 vs. 0.64, p < 0.01).

Conclusion

We found comparable efficacy of IRT and PA in patients with IgSD ± SPAD. Patients with persistent infections during treatment with PA had less infections after switching to IRT.

Clinical Implication

Given the costs and associated side-effects of IRT, it should be reserved for patients with persistent infections despite treatment with PA.

Electronic supplementary material

The online version of this article (10.1007/s10875-020-00841-3) contains supplementary material, which is available to authorized users.

How to investigate a suspected immune deficiency in adults

Patients with immune deficiencies can present with variable clinical phenotypes. This often translates into a significant delay in their diagnosis, and resultant patient morbidity. This review summarises the most common types of immunodeficiency disorders, primary and secondary, along with their key features. It provides a structured approach for the clinician on when to suspect an immunodeficiency, the initial investigations pathway and when a specialist referral should be considered.

Reference values of leukocyte and lymphocytes populations in umbilical cord and capillary blood in healthy Mexican newborns

INTRODUCTION

In newborns, dramatic changes occur in the blood and bone marrow during the first hours; there are rapid fluctuations in the quantities of leukocytes populations. In this work, we investigated leukocytes subsets counts in two types of blood samples (cord blood and capillary blood) extracted from healthy newborns.

METHODS

Blood samples from Mexican neonates were collected by Instituto Nacional de Pediatría with written informed consent. For all samples we determined leukocytes populations; neutrophils, monocytes, total lymphocytes, and populations: T CD3+ cells, TCD4+ cells, T CD8+ cells, B CD19+ cells and NK CD16+56 cells by flow cytometry. We used the Mann-Whitney U test to compare leukocytes of cord and capillary blood; also to analyze the differences between gender and we obtained reference values of the cord and capillary blood in neonates.

RESULTS

We observed higher absolute counts and frequencies of total lymphocyte in capillary blood compared with cord blood. In absolute numbers, the capillary blood showed significant differences in neutrophils, monocytes, lymphocytes, T CD3+ cells, T CD4+ cells, T CD8+ cells, B CD19+ cells, and NK cells; no significant differences were observed between genders.

DISCUSSION

Our data contribute to newborn Mexican reference values for all these populations of leukocytes. We found that the dispersal range differs between the two types of blood, suggesting a different fate in the immune response. Immunophenotyping of the blood cell population to identify these cells is an essential tool in the diagnosis and follow-up of neonates with immunodeficiencies and other immune disorders.

Primary Immunodeficiencies: Diseases of Children and Adults - A Review

Primary immunodeficiencies (PIDs) belong to a group of rare congenital diseases occurring all over the world that may be seen in both children and adults. In most cases, genetic predispositions are already known. As shown in this review, genetic abnormalities may be related to dysfunction of the immune system, which manifests itself as recurrent infections, increased risk of cancer, and autoimmune diseases. This article reviews the various forms of PIDs, including their characterization, management strategies, and complications. Novel aspects of the diagnostics and monitoring of PIDs are presented.

Immunoglobulin replacement for secondary immunodeficiency after B-cell targeted therapies in autoimmune rheumatic disease: Systematic literature review

BACKGROUND

Consensus guidelines are not available for the use of immunoglobulin replacement therapy (IGRT) in patients developing iatrogenic secondary antibody deficiency following B-cell targeted therapy (BCTT) in autoimmune rheumatic disease.

OBJECTIVES

To evaluate the role of IGRT to manage hypogammaglobulinemia following BCTT in autoimmune rheumatic disease (AIRD).

METHODS

Using an agreed search string we performed a systematic literature search on Medline with Pubmed as vendor. We limited the search to English language papers with abstracts published over the last 10 years. Abstracts were screened for original data regarding hypogammaglobulinemia following BCTT and the use of IGRT for hypogammaglobulinemia following BCTT. We also searched current recommendations from national/international organisations including British Society for Rheumatology, UK Department of Health, American College of Rheumatology, and American Academy of Asthma, Allergy and Immunology.

RESULTS

222 abstracts were identified. Eight papers had original relevant data that met our search criteria. These studies were largely retrospective cohort studies with small patient numbers receiving IGRT. The literature highlights the induction of a sustained antibody deficiency, risk factors for hypogammaglobulinemia after BCTT including low baseline serum IgG levels, how to monitor patients for the development of hypogammaglobulinemia and the limited evidence available on intervention thresholds for commencing IGRT.

CONCLUSION

The benefit of BCTT needs to be balanced against the risk of inducing a sustained secondary antibody deficiency. Consensus guidelines would be useful to enable appropriate assessment prior to and following BCTT in preventing and diagnosing hypogammaglobulinemia. Definitions for symptomatic hypogammaglobulinemia, intervention thresholds and treatment targets for IGRT, and its cost-effectiveness are required.

Skin disorders are prominent features in primary immunodeficiency diseases: A systematic overview of current data

Primary immunodeficiency diseases (PIDs) are characterized by an increased risk of infections, autoimmunity, autoinflammation, malignancy, and allergic disorders. Skin disorders are also common clinical features in PIDs and may be among the presenting manifestations. Recognition of specific PID-associated skin conditions in combination with other clinical features as described in the currently used warning signs could raise suspicion of an underlying PID. We aimed to provide a systematically obtained overview of skin disorders and their prevalence in PIDs. Secondary, the prevalence of Staphylococcus (S.) aureus-associated skin disorders and atopy was reviewed, as these are the most prominent skin features in PIDs. A systematic search was performed in EMBASE, MEDLINE, Web of Science, Cochrane, and Google Scholar (up to May 9, 2018). All original observational and experimental human studies that address the presence of skin disorders in PIDs were selected. We rated study quality using the Institute of Health Economics Quality Appraisal Checklist for Case Series Studies. Sixty-seven articles (5030 patients) were included. Study quality ranged from 18.2% to 88.5%. A broad spectrum of skin disorders was reported in 30 PIDs, mostly in single studies with a low number of included patients. An overview of associated PIDs per skin disorder was generated. Data on S. aureus-associated skin disorders and atopy in PIDs were limited. In conclusion, skin disorders are prominent features in PIDs. Through clustering of PIDs per skin disorder, we provide a support tool to use in clinical practice that should raise awareness of PIDs based on presenting skin manifestations.

Mild Hypogammaglobulinemia Can Be a Serious Condition

Background: Most patients with primary antibody deficiency (PAD) suffer from less well-described and understood forms of hypogammaglobulinemia (unclassified primary antibody deficiency, unPAD). Because of the moderately decreased immunoglobulin levels compared to CVID, unPAD is generally considered to be clinically mild and not very relevant.

Objective: To describe our cohort of—mainly—unPAD patients, and to analyze whether subgroups can be identified.

Methods: Data were prospectively collected (February-2012 to June-2016) as part of a standardized, 1-day Care Pathway for suspected primary immunodeficiency. The TNO-AZL Questionnaire for Health-Related Quality of Life (HRQoL) was part of the pre-first-visit intake procedure.

Results: Three hundred and twenty patients were referred to the Care Pathway. Data from 23/27 children and 99/113 adults who were diagnosed with PAD and gave informed consent were available for analysis. 89/99 adults had unPAD, the majority (74%) were female and 44% already showed bronchiectasis. HRQoL was significantly decreased in all domains, meaning that a lot of unPAD patients had to cope simultaneously with pain, negative feelings and impairments in cognition, home management tasks, sleep, social interaction, and work. The most prominently impaired HRQoL domain was vitality, indicating these patients feel extremely tired and worn out.

Conclusion: These results highlight the need for more attention to the potential patient burden of unPADs. A larger cohort is needed to increase our understanding of unPADs and to analyze whether distinct subgroups can be identified. For now, it is important for the clinician to acknowledge the existence of unPAD and be aware of its potential consequences, in order to timely and appropriately manage its effects and complications.

B-cell receptor repertoire sequencing in patients with primary immunodeficiency: a review

The advent of next-generation sequencing (NGS) now allows a detailed assessment of the adaptive immune system in health and disease. In particular, high-throughput B-cell receptor (BCR) repertoire sequencing provides detailed information about the functionality and abnormalities of the B-cell system. However, it is mostly unknown how the BCR repertoire is altered in the context of primary immunodeficiencies (PID) and whether findings are consistent throughout phenotypes and genotypes. We have performed an extensive literature search of the published work on BCR repertoire sequencing in PID patients, including several forms of predominantly antibody disorders and combined immunodeficiencies. It is somewhat surprising that BCR repertoires, even from severe clinical phenotypes, often show only mild abnormalities and that diversity or immunoglobulin gene segment usage is generally preserved to some extent. Despite the great variety of wet laboratory and analytical methods that were used in the different studies, several findings are common to most investigated PIDs, such as the increased usage of gene segments that are associated with self-reactivity. These findings suggest that BCR repertoire characteristics may be used to assess the functionality of the B-cell compartment irrespective of the underlying defect. With the use of NGS approaches, there is now the opportunity to apply BCR repertoire sequencing to multiple patients and explore the PID BCR repertoire in more detail. Ultimately, using BCR repertoire sequencing in translational research could aid the management of PID patients by improving diagnosis, estimating functionality of the immune system and improving assessment of prognosis.

The 2017 IUIS Phenotypic Classification for Primary Immunodeficiencies

Since the 1990s, the International Union of Immunological Societies (IUIS) PID expert committee (EC), now called Inborn Errors of Immunity Committee, has published every other year a classification of the inborn errors of immunity. This complete catalog serves as a reference for immunologists and researchers worldwide. However, it was unadapted for clinicians at the bedside. For those, the IUIS PID EC is now publishing a phenotypical classification since 2013, which proved to be more user-friendly. There are now 320 single-gene inborn errors of immunity underlying phenotypes as diverse as infection, malignancy, allergy, auto-immunity, and auto-inflammation. We herein propose the revised 2017 phenotypic classification, based on the accompanying 2017 IUIS Inborn Errors of Immunity Committee classification.

International Union of Immunological Societies: 2017 Primary Immunodeficiency Diseases Committee Report on Inborn Errors of Immunity

Beginning in 1970, a committee was constituted under the auspices of the World Health Organization (WHO) to catalog primary immunodeficiencies. Twenty years later, the International Union of Immunological Societies (IUIS) took the remit of this committee. The current report details the categorization and listing of 354 (as of February 2017) inborn errors of immunity. The growth and increasing complexity of the field have been impressive, encompassing an increasing variety of conditions, and the classification described here will serve as a critical reference for immunologists and researchers worldwide.

Primary Immune Deficiencies in the Adult: A Previously Underrecognized Common Condition

The large majority of classified primary immune deficiency (PID) diseases present in childhood. Yet, most patients with PID are adults, with a large proportion experiencing onset of symptoms beyond their childhood years. Most of these are diagnosed predominantly with antibody defects, but cellular and other disorders are increasingly being identified in older patients as well. Moreover, advances in clinical immunology are allowing pediatric patients, even those with severe disease, to reach adulthood. Because of differences in the physiology and pathophysiology of children and adults, the presentation, diagnosis, and management of a complex chronic disease could differ significantly between these patient populations and therefore require modifications in approach.

Early diagnosis of PI3Kδ syndrome in a 2 years old girl with recurrent otitis and enlarged spleen

Heterozygous gain of function mutations in the gene encoding p110δ subunit of PI3K have been recently associated with activated PI3K-δ syndrome (APDS), a novel combined immune deficiency characterized by recurrent sinopulmonary infections, lymphopenia, reduced class-switched memory B cells, lymphadenopathy, CMV and/or EBV viremia and EBV-related lymphoma. Here we report a dominant gain of function PIK3CD mutation (E1021K) in a patient presenting with recurrent otitis media, massive splenomegaly, and persistent EBV-viraemia. The immunological studies showed low IgA level, but normal IgM, IgG, and normal antibody response to diphtheria and tetanus toxoid vaccination. Analysis of B lymphocyte subsets revealed abnormal expansion of transitional B cells, and low percentage of switched CD27⁺IgD^- and CD27⁺IgD⁺ memory B cells. Analysis of T cell compartment unveiled prevalence of terminally differentiated cells. This study suggests that PIK3CD gain of function mutations should be suspected despite incomplete phenotype in patients with early onset splenomegaly, persistent EBV viremia and abnormal B and T cell subsets despite normal IgG levels. Currently the optimal treatment is still debated, but prompt management can hopefully diminish incidence of severe long-lasting sequelae (i.e. bronchiectasis, ear and sinus damage).

Uses of Next-Generation Sequencing Technologies for the Diagnosis of Primary Immunodeficiencies

Primary immunodeficiencies (PIDs) are genetic disorders impairing host immunity, leading to life-threatening infections, autoimmunity, and/or malignancies. Genomic technologies have been critical for expediting the discovery of novel genetic defects underlying PIDs, expanding our knowledge of the complex clinical phenotypes associated with PIDs, and in shifting paradigms of PID pathogenesis. Once considered Mendelian, monogenic, and completely penetrant disorders, genomic studies have redefined PIDs as a heterogeneous group of diseases found in the global population that may arise through multigenic defects, non-germline transmission, and with variable penetrance. This review examines the uses of next-generation DNA sequencing (NGS) in the diagnosis of PIDs. While whole genome sequencing identifies variants throughout the genome, whole exome sequencing sequences only the protein-coding regions within a genome, and targeted gene panels sequence only a specific cohort of genes. The advantages and limitations of each sequencing approach are compared. The complexities of variant interpretation and variant validation remain the major challenge in wide-spread implementation of these technologies. Lastly, the roles of NGS in newborn screening and precision therapeutics for individuals with PID are also addressed.

Adoptive T Cell Immunotherapy for Patients with Primary Immunodeficiency Disorders

Primary immunodeficiency disorders (PID) are a group of inborn errors of immunity with a broad range of clinical severity but often associated with recurrent and serious infections. While hematopoietic stem cell transplantation (HSCT) can be curative for some forms of PID, chronic and/or refractory viral infections remain a cause of morbidity and mortality both before and after HSCT. Although antiviral pharmacologic agents exist for many viral pathogens, these are associated with significant costs and toxicities and may not be effective for increasingly drug-resistant pathogens. Thus, the emergence of adoptive immunotherapy with virus-specific T lymphocytes (VSTs) is an attractive option for addressing the underlying impaired T cell immunity in many PID patients. VSTs have been utilized for PID patients following HSCT in many prior phase I trials, and may potentially be beneficial before HSCT in patients with chronic viral infections. We review the various methods of generating VSTs, clinical experience using VSTs for PID patients, and current limitations as well as potential ways to broaden the clinical applicability of adoptive immunotherapy for PID patients.

A multicentre, prospective, non-randomized, sequential, open-label trial to demonstrate the bioequivalence between intravenous immunoglobulin new generation (IGNG) and standard IV immunoglobulin (IVIG) in adult patients with primary immunodeficiency (PID)

OBJECTIVES

To demonstrate the bioequivalence between 2 intravenous immunoglobulin (IVIG) preparations, TEGELINE^® and ClairYg^®, a ready-to-use 5% IVIG, in primary immunodeficiency (PID). Secondary objectives were to assess the efficacy, safety and pharmacokinetics of ClairYg^®.

METHODS

Twenty-two adult PID patients receiving stable doses of TEGELINE^® (5% lyophilized IVIG) were switched to ClairYg^® for 6 months. ClairYg^® was administered under the same conditions as TEGELINE^®, either every 3 or 4 weeks. The primary endpoint was mean average total IgG trough level at steady state with ClairYg^® versus TEGELINE^®. Clinical efficacy was also assessed in terms of infections and associated events.

RESULTS

Bioequivalence was established with a mean average total IgG trough level at steady state being 8.05g/L with TEGELINE^® and 9.17g/L with ClairYg^® (i.e. geometric mean for the difference between ClairYg^® and TEGELINE^® was 1.136; [90% CI: 1.092-1.181] P<0.001), within the pre-specified margin to establish bioequivalence (0.80-1.25). Total IgG trough levels remained clinically adequate (>4-6g/L) throughout the study. No patient was hospitalized for infection or had serious bacterial infections while receiving ClairYg^®. The median annualized infections rate per patient was similar for both products: 4.35 [0; 21.8] for TEGELINE^® and 4.30 [0; 15.1] for ClairYg^®. Infections were less common with higher IgG trough levels (>8.16g/L). ClairYg^® showed good safety, in particular good hepatic and renal tolerance, and did not induce hemolysis. ClairYg^® pharmacokinetics profile was comparable to that of TEGELINE^®.

CONCLUSION

ClairYg^® is safe and effective in the treatment of adult PID.

Approach to the Management of Autoimmunity in Primary Immunodeficiency

Primary immunodeficiency diseases (PIDs) consist of a genetically heterogeneous group of immune disorders that affect distinct elements of the immune system. PID patients are more prone to infections and non-infectious complications, particularly autoimmunity. The concomitance of immunodeficiency and autoimmunity appears to be paradoxical and leads to difficulty in the management of autoimmune complications in PID patients. Therefore, management of autoimmunity in patients with PID requires special considerations because dysregulations and dysfunctions of the immune system along with persistent inflammation impair the process of diagnosis and treatment.

Primary immunodeficiencies in Chile evaluated through ICD-10 coded hospital admissions

BACKGROUND

The epidemiology and hospitalisation trends of primary immunodeficiency (PID) in Chile are unknown. We aimed to evaluate hospitalisation trends and demographic characteristics of PID admissions in Chile.

METHODS

PID admissions between 2001 and 2010 (ICD-10 codes D70.0, D70.4, D71, 72.0, D76.1, D80-D84, E70.3, G11.3) were reviewed using national hospital discharge databases.

RESULTS

During the study period, 5486 admissions due to PID were registered (0.03% of total). 58.5% of patients were male and 66.3% were under 18 years. Median length of stay was one day (range 1-403 days). The most frequent diagnoses were hypogammaglobulinaemia (27.6%), unspecified immunodeficiency (21.9%), haemophagocytic lymphohystiocytosis (18.3%) and common variable immunodeficiency (11.2%). There was a significant increase in PID admission rate and in one-day hospitalisations during this period (β=0.2; P=0.001 and β=33; P≤0.001, respectively), however no significant variation was found for longer admissions (β=4.8; P=0.175). The increasing trend in PID admission rate was significant in patients with private, but not public insurance (β=0.53; P≤0.001 vs. β=0.08; P=0.079, respectively).

CONCLUSIONS

We report an increasing trend in admissions due to PID in Chile over a 10-year period. Increase is mainly due to short hospitalisations, possibly accounting for improvements in IVIG access. Higher admission rates in patients with private vs. public insurance suggest socioeconomic disparities in access to PID treatment. ICD-10 coded hospitalisation databases may be useful to determine hospitalisation trends and demographic characteristics of PID admissions worldwide.

Beyond the “Choosing wisely”: a possible attempt

Since the fundamental principles of the medical profession were clearly defined in a physician charter in 2002, special considerations have been expressed about the adequate distribution of health care resources taking in account the individual patient needs to optimize the health care service. The correct application of procedures represents a key point in order to reach the appropriateness of care, that means to avoid unnecessary or inappropriate procedures as well as the underutilization of the necessary procedures. In this context, the Choosing wisely campaign have been widely used and disclosed and even the Italian Society of Pediatric Allergology and Immunology - SIAIP has been working to make recommendations in order to ensure the appropriateness of care in the field of allergy and optimize the use of health care resources.

B-cell activation with CD40L or CpG measures the function of B-cell subsets and identifies specific defects in immunodeficient patients

Around 65% of primary immunodeficiencies are antibody deficiencies. Functional tests are useful tools to study B-cell functions in vitro. However, no accepted guidelines for performing and evaluating functional tests have been issued yet. Here, we report our experience on the study of B-cell functions in infancy and throughout childhood. We show that T-independent stimulation with CpG measures proliferation and differentiation potential of memory B cells. Switched memory B cells respond better than IgM memory B cells. On the other hand, CD40L, a T-dependent stimulus, does not induce plasma cell differentiation, but causes proliferation of naïve and memory B cells. During childhood, the production of plasmablasts in response to CpG increases with age mirroring the development of memory B cells. The response to CD40L does not change with age. In patients with selective IgA deficiency (SIgAD), we observed that switched memory B cells are reduced due to the absence of IgA memory B cells. In agreement, IgA plasma cells are not generated in response to CpG. Unexpectedly, B cells from SIgAD patients show a reduced proliferative response to CD40L. Our results demonstrate that functional tests are an important tool to assess the functions of the humoral immune system.

Exome and genome sequencing for inborn errors of immunity

The advent of next-generation sequencing (NGS) in 2010 has transformed medicine, particularly the growing field of inborn errors of immunity. NGS has facilitated the discovery of novel disease-causing genes and the genetic diagnosis of patients with monogenic inborn errors of immunity. Whole-exome sequencing (WES) is presently the most cost-effective approach for research and diagnostics, although whole-genome sequencing offers several advantages. The scientific or diagnostic challenge consists in selecting 1 or 2 candidate variants among thousands of NGS calls. Variant- and gene-level computational methods, as well as immunologic hypotheses, can help narrow down this genome-wide search. The key to success is a well-informed genetic hypothesis on 3 key aspects: mode of inheritance, clinical penetrance, and genetic heterogeneity of the condition. This determines the search strategy and selection criteria for candidate alleles. Subsequent functional validation of the disease-causing effect of the candidate variant is critical. Even the most up-to-date dry lab cannot clinch this validation without a seasoned wet lab. The multifariousness of variations entails an experimental rigor even greater than traditional Sanger sequencing-based approaches in order not to assign a condition to an irrelevant variant. Finding the needle in the haystack takes patience, prudence, and discernment.

Primary immunodeficiencies associated with eosinophilia

Background

Eosinophilia is not an uncommon clinical finding. However, diagnosis of its cause can be a dilemma once common culprits, namely infection, allergy and reactive causes are excluded. Primary immunodeficiency disorders (PID) are among known differentials of eosinophilia. However, the list of PIDs typically reported with eosinophilia is small and the literature lacks an inclusive list of PIDs which have been reported with eosinophilia. This motivated us to review the literature for all PIDs which have been described to have elevated eosinophils as this may contribute to an earlier diagnosis of PID and further the understanding of eosinophilia.

Methods

A retrospective PubMed, and Google Scholar search using the terms “eosinophilia” and “every individual PID” as classified by Expert Committee of the International Union of Immunological Societies with the limit of the English language was performed. Results were assessed to capture case(s) which reported eosinophilia in the context of PID conditions. Absolute eosinophil counts (AEC) were retrieved from manuscripts whenever reported.

Results

In addition to the typical PID conditions described with eosinophilia, we document that MHC class II deficiency, CD3γ deficiency, STAT1 deficiency (AD form), Kostmann disease, cyclic neutropenia, TCRα deficiency, Papillon-Lefevre syndrome, CD40 deficiency, CD40L deficiency, anhidrotic ectodermal dysplasia with immune deficiency, ataxia-telangiectasia, common variable immunodeficiency disorders (CVID), Blau syndrome, CARD9 deficiency, neonatal onset multisystem inflammatory disease or chronic infantile neurologic cutaneous and articular syndrome (NOMID/CINCA), chronic granulomatous disease, MALT1 deficiency and Roifman syndrome have been noted to have elevated eosinophils. Severe eosinophilia (>5.0 × 10⁹/L) was reported in Omenn syndrome, Wiskott Aldrich syndrome, ADA deficiency, autoimmune lymphoproliferative syndrome, immunodysregulation polyendocrinopathy enteropathy X-linked, STAT3 deficiency, DOCK8 deficiency, CD40 deficiency, MHC II deficiency, Kostmann disease, Papillon-Lefevre syndrome, and CVID.

Conclusions

This literature review shows that there is an extensive list of PIDs which have been reported with eosinophilia. This list helps clinicians to consider an extended differential diagnoses when tasked with exclusion of PID as a cause for eosinophilia.

Electronic supplementary material

The online version of this article (doi:10.1186/s13223-016-0130-4) contains supplementary material, which is available to authorized users.

Newborn screening for SCID: lessons learned

INTRODUCTION

Newborn screening (NBS) for Severe combined immunodeficiency (SCID)/severe T cell lymphopenia (sTCL) is being increasingly used worldwide.

AREAS COVERED

In this manuscript we will discuss the following: 1) The rationale for screening newborns for SCID/sTCL; 2) The scientific basis for the use of the T cell receptor excision circle (TREC) assay in screening newborns for SCID/sTCL; 3) The published outcomes of current NBS programs. Expert commentary: 4) Some of the ethical dilemmas that occur when screening newborns for SCID. Finally, we will discuss the future directions for expanding NBS to include other primary immunodeficiencies.

Primary immunodeficiency for the primary care provider

Primary immunodeficiencies are a group of heterogeneous disorders resulting from defects affecting the function of ≥1 parts of the immune system. Current estimates of the prevalence of primary immunodeficiency disease are one in 1200 patients. In Ontario, where the average general practitioner follows 1300 to 2000 patients, an estimated two patients will have primary immunodeficiency. With new primary immunodeficiencies being described at an exponential rate, and those previously described becoming better understood, it is challenging for health care providers to stay up to date. Knowledge gaps delay diagnosis and treatment, leading to increased morbidity and mortality. The present review aims to provide the primary care provider with the tools necessary to recognize primary immunodeficiency and assist in establishing diagnoses.

Flow Cytometry, a Versatile Tool for Diagnosis and Monitoring of Primary Immunodeficiencies

Genetic defects of the immune system are referred to as primary immunodeficiencies (PIDs). These immunodeficiencies are clinically and immunologically heterogeneous and, therefore, pose a challenge not only for the clinician but also for the diagnostic immunologist. There are several methodological tools available for evaluation and monitoring of patients with PIDs, and of these tools, flow cytometry has gained prominence, both for phenotyping and functional assays. Flow cytometry allows real-time analysis of cellular composition, cell signaling, and other relevant immunological pathways, providing an accessible tool for rapid diagnostic and prognostic assessment. This minireview provides an overview of the use of flow cytometry in disease-specific diagnosis of PIDs, in addition to other broader applications, which include immune phenotyping and cellular functional measurements.

Family Physician Perspectives on Primary Immunodeficiency Diseases

Primary immunodeficiency diseases (PIDs) include over 250 diverse disorders. The current study assessed management of PID by family practice physicians. The American Academy of Allergy, Asthma, and Immunology Primary Immunodeficiency Committee and the Immune Deficiency Foundation conducted an incentivized mail survey of family practice physician members of the American Medical Association and the American Osteopathic Association in direct patient care. Responses were compared with subspecialist immunologist responses from a similar survey. Surveys were returned by 528 (of 4500 surveys mailed) family practice physicians, of whom 44% reported following ≥1 patient with PID. Selective immunoglobulin A deficiency (21%) and chronic granulomatous disease (11%) were most common and were followed by significantly more subspecialist immunologists (P < 0.05). Use of intravenously administered immunoglobulin and live viral vaccinations across PID was significantly different (P < 0.05). Few family practice physicians were aware of professional guidelines for diagnosis and management of PID (4 vs. 79% of subspecialist immunologists, P < 0.05). Family practice physicians will likely encounter patients with PID diagnoses during their career. Differences in how family practice physicians and subspecialist immunologists manage patients with PID underscore areas where improved educational and training initiatives may benefit patient care.

Recombinase Activating Gene 1 Deficiencies Without Omenn Syndrome May Also Present With Eosinophilia and Bone Marrow Fibrosis

Background

Severe combined immunodeficiency (SCID) syndromes are a heterogenous group of diseases characterized by impairment in both cellular and humoral immunity with a range of genetic disorders. Complete recombinase activating gene (RAG) deficiency is associated with classical T^-B^-NK⁺ SCID which is the most common phenotype of Turkish SCID patients. There is a broad spectrum of hypomorfic RAG mutations including Omenn syndrome, leaky or atypical SCID with expansion of γδ T cells, autoimmunity and cytomegalovirus (CMV) infections.

Methods

Twenty-one (44%) patients had RAG1 deficiency of all 44 SCID patients followed up by pediatric immunology department. A retrospective analysis was conducted on the medical records of all SCID patients with RAG1 deficiency.

Results

Eight patients were classified as T^-B^-NK⁺ SCID, five patients as T⁺B^-NK⁺ SCID (three of these were Omenn phenotype), and eight patients as T⁺B⁺NK⁺ SCID phenotype. Mean age of the whole study group, mean age at onset of symptoms and mean age at diagnosis were 87.7 ± 73.8 (12 - 256), 4.4 ± 8.2 (1 - 36) and 29.1 ± 56.8 (1 - 244) months, respectively. Consanguinity was present in 11 (52%) of 21 patients. Autoimmunity was found in six patients (28%). Ten patients (47%) had CMV infection, four (19%) had Epstein-Barr virus (EBV) infections and three (14%) had Bacillus Calmette-Guerin (BCG) infections. Seven patients who had refractory cytopenia (two pancytopenia and five bicytopenia) underwent bone marrow biopsy, three of whom had bone marrow fibrosis. Future evaluations must be considered about bone marrow fibrosis in RAG1 deficiency patients. Eosinophilia was observed in 10 patients, seven of whom did not have Omenn phenotype.

Conclusion

Non-Omenn phenotype RAG1 deficiencies can also present with eosinophilia. This report is presented to emphasize that RAG1 mutations may lead to diverse clinical phenotypes.

Common Variable Immunodeficiency and Circulating TFH

CD4+ T follicular helper cells (T_FH) were assessed in adult patients with common variable immune deficiency (CVID) classified according to the presence of granulomatous disease (GD), autoimmunity (AI), or both GD and AI (Group I) or the absence of AI and GD (Group II). T_FH lymphocytes were characterized by expression of CXCR5 and PD-1. T_FH were higher (in both absolute number and percentage) in Group I than in Group II CVID patients and normal controls (N). Within CXCR5+CD4+ T cells, the percentage of PD-1 (+) was higher and that of CCR7 (+) was lower in Group I than in Group II and N. The percentages of Treg and T_FH reg were similar in both CVID groups and in N. T_FH responded to stimulation increasing the expression of the costimulatory molecules CD40L and ICOS as did N. After submitogenic PHA+IL-2 stimulation, intracellular expression of T_FH cytokines (IL-10, IL-21) was higher than N in Group I, and IL-4 was higher than N in Group II. These results suggest that T_FH are functional in CVID and highlight the association of increased circulating T_FH with AI and GD manifestations.

Combined Autoimmune Cytopenias Presenting in Childhood

BACKGROUND

Pediatric patients with chronic and/or refractory autoimmune multi-lineage cytopenias present challenges in both diagnosis and management. Increasing availability of diagnostic testing has revealed an underlying immune dysfunction in patients previously diagnosed with Evans Syndrome. However, the data are sparse and the majority of patients are adults.

PROCEDURE

We performed a retrospective chart review to document the natural history of 23 pediatric patients with autoimmune multi-lineage cytopenias followed at three tertiary care pediatric hematology clinics.

RESULTS

Investigations revealed seven patients (30.4%) with an autoimmune lymphoproliferative-like syndrome and six patients (26.1%) with other primary immunodeficiencies. Only one (4.3%) patient was suspected to have systemic lupus erythematosus and six patients (26.1%) had other types of autoimmunity. Treatment consisted of immunosuppressive therapy, intravenous gammaglobulin, and splenectomy. Supportive care included granulocyte-colony stimulating factor, and blood product transfusions. Two patients (8.7%) died. Complete remission was achieved in 3 patients (13.0%); of the remaining, 14 patients (60.9%) had chronic immune thrombocytopenic purpura, 10 patients (43.5%) chronic autoimmune neutropenia, and 4 patients (17.4%) chronic autoimmune hemolytic anemia with a median follow up of 5 years (2 months-12 years).

CONCLUSIONS

These data suggest that pediatric patients presenting with autoimmune multi-lineage cytopenias should undergo investigation for underlying immune dysregulation, including autoimmune lymphoproliferative syndrome, other primary immunodeficiencies and autoimmune disorders. The development of an international registry for such patients is imperative to improve the understanding of their complex natural history.

Combined immunodeficiencies: twenty years experience from a single center in Turkey

Combined immunodeficiencies (CIDs) include a group of inherited monogenic disorders. CIDs are characterized by defective cellular and humoral immunities that lead to severe infections. CIDs can be classified according to immunologic phenotypes as T^–B^–NK^– CID, T^–B^–NK⁺ CID, T^–B⁺NK^– CID and T^–B⁺NK⁺ CID. In a 20-year period, from 1994 to 2014, a total of 40 CID patients were diagnosed at the Pediatric Immunology of Erciyes University Medical Faculty in Kayseri, Turkey. The gender ratio (F/M) was 3/5. The median age at the onset of symptoms was 2 months (range, 15 days – 15 years). Of the 14 T^–B^–NK^– CIDs, 6, 2 (siblings), 1, 1 and 4 had a mutation in the ADA, PNP, Artemis, RAG1 genes and unknown genetic diagnosis respectively. Of the 15 T^–B^–NK⁺ CIDs, 3, 2 (siblings) and 10 had a mutation in the RAG1, XLF/Cernunnos genes and unknown genetic diagnosis respectively. Of the 9 T^–B⁺NK^– CIDs, 2 siblings, 1, 1 and 5 had a mutation in the ZAP70, IL2RG, DOCK8 genes and unknown genetic diagnosis respectively. Of the 2 T^–B⁺NK⁺ CIDs, 2 had a mutation in the MAGT1 and ZAP70 genes respectively. Of the 40 CIDs, 26 (65%) were died and 14 (35%) are alive. Eight patients received HSCT (hematopoietic stem cell transplantation) with 62.5% survival rate. As a result, patients presented with severe infections in the first months of life have to be examined for CIDs. Shortening time of diagnosis would increase chance of HSCT as life-saving treatment in the CID patients.

Human genetic basis of interindividual variability in the course of infection

The key problem in human infectious diseases was posed at the turn of the 20th century: their pathogenesis. For almost any given virus, bacterium, fungus, or parasite, life-threatening clinical disease develops in only a small minority of infected individuals. Solving this infection enigma is important clinically, for diagnosis, prognosis, prevention, and treatment. Some microbes will inevitably remain refractory to, or escape vaccination, or chemotherapy, or both. The solution also is important biologically, because the emergence and evolution of eukaryotes alongside more rapidly evolving prokaryotes, archaea, and viruses posed immunological challenges of an ecological and evolutionary nature. We need to study these challenges in natural, as opposed to experimental, conditions, and also at the molecular and cellular levels. According to the human genetic theory of infectious diseases, inborn variants underlie life-threatening infectious diseases. Here I review the history of the field of human genetics of infectious diseases from the turn of the 19th century to the second half of the 20th century. This paper thus sets the scene, providing the background information required to understand and appreciate the more recently described monogenic forms of resistance or predisposition to specific infections discussed in a second paper in this issue.

The 2015 IUIS Phenotypic Classification for Primary Immunodeficiencies

There are now nearly 300 single-gene inborn errors of immunity underlying phenotypes as diverse as infection, malignancy, allergy, auto-immunity, and auto-inflammation. For each of these five categories, a growing variety of phenotypes are ascribed to Primary Immunodeficiency Diseases (PID), making PIDs a rapidly expanding field of medicine. The International Union of Immunological Societies (IUIS) PID expert committee (EC) has published every other year a classification of these disorders into tables, defined by shared pathogenesis and/or clinical consequences. In 2013, the IUIS committee also proposed a more user-friendly, phenotypic classification, based on the selection of key phenotypes at the bedside. We herein propose the revised figures, based on the accompanying 2015 IUIS PID EC classification.

Cardiovascular abnormalities in primary immunodeficiency diseases

In recent years, increasing numbers of patients with primary immune deficiency (PID) are being recognized as also suffering from cardiovascular system (CVS) abnormalities. These CVS defects might be explained by infectious or autoimmune etiologies, as well as by the role of specific genes and the immune system in the development and function of CVS tissues. Here, we provide the first comprehensive review of the clinical, potentially pathogenic mechanisms, and the management of PID, as well as the associated immune and CVS defects. In addition to some well-known associations of PID with CVS abnormalities, such as DiGeorge syndrome and CHARGE anomaly, we describe the cardiac defects associated with Omenn syndrome, calcium channel deficiencies, DNA repair defects, common variable immunodeficiency, Roifman syndrome, various neutrophil/macrophage defects, FADD deficiency, and HOIL1 deficiency. Moreover, we detail the vascular abnormalities recognized in chronic mucocutaneous candidiasis, chronic granulomatous disease, Wiskott–Aldrich syndrome, Schimke immuno-osseus dysplasia, hyper-IgE syndrome, MonoMAC syndrome, and X-linked lymphoproliferative disease. In conclusion, the expanding spectrum of PID requires increased alertness to the possibility of CVS involvement as an important contributor to the diagnosis and management of these patients.

Therapeutic Immunoglobulin Selected for High Antibody Titer to RSV also Contains High Antibody Titers to Other Respiratory Viruses

Specific antibodies against infections most relevant to patients with primary immunodeficiency diseases are not routinely evaluated in commercial polyclonal immunoglobulin preparations. A polyclonal immunoglobulin prepared from plasma of donors having high neutralizing antibody titers to respiratory syncytial virus (RSV) was studied for the presence of antibody titers against seven additional respiratory viruses. While donors were not selected for antibody titers other than against RSV, the immunoglobulin preparation had significantly higher titers to 6 of 7 viruses compared to those present in 10 commercially available therapeutic immunoglobulin products (p ≤ 0.01 to p ≤ 0.001). To consider this as a donor-specific attribute, 20 random donor plasma samples were studied individually and identified a significant correlation between the RSV antibody titer and other respiratory virus titers: donors with high RSV titers were more likely to have higher titers to other respiratory viruses. These findings suggest either some humoral antiviral response bias or more frequent viral exposure of certain individuals.

The use of databases in primary immunodeficiencies

PURPOSE OF REVIEW

We provide an overview on the latest developments in primary immunodeficiency registries worldwide, on the basis of the recent literature amended by some older references to achieve completeness.

RECENT FINDINGS

New primary immunodeficiency registries are emerging worldwide, although existing databases continue to thrive and provide valuable insights for clinicians and researchers.

SUMMARY

In the area of rare disease research, data on a meaningful number of patients can only be achieved via collaboration. Registries for primary immunodeficiency are organized on different geographic levels and appear in various technical forms. Some registries are operated within single departments or hospitals, whereas others collect data from a country in the form of a national registry. With modern information technology and networks, it has become feasible to easily extend documentation to the transnational level. Most patient registries cover similar but not identical sets of data, whereas some have a special focus on, for example, genetics or incorporate only data from patients who have undergone a specific form of treatment. This review shows the usefulness and power of international immunodeficiency registries, as well as possible hurdles and limitations.

Primary immune deficiencies - principles of care

Primary immune deficiencies (PIDs) are a growing group of over 230 different disorders caused by ineffective, absent or an increasing number of gain of function mutations in immune components, mainly cells and proteins. Once recognized, these rare disorders are treatable and in some cases curable. Otherwise untreated PIDs are often chronic, serious, or even fatal. The diagnosis of PIDs can be difficult due to lack of awareness or facilities for diagnosis, and management of PIDs is complex. This document was prepared by a worldwide multi-disciplinary team of specialists; it aims to set out comprehensive principles of care for PIDs. These include the role of specialized centers, the importance of registries, the need for multinational research, the role of patient organizations, management and treatment options, the requirement for sustained access to all treatments including immunoglobulin therapies and hematopoietic stem cell transplantation, important considerations for developing countries and suggestions for implementation. A range of healthcare policies and services have to be put into place by government agencies and healthcare providers, to ensure that PID patients worldwide have access to appropriate and sustainable medical and support services.

Historical perspectives in the diagnosis and treatment of primary immune deficiencies

The field of Primary Immune Deficiency Disorders (PIDD) has advanced rapidly over the past several years with over 200 different gene mutations defined. With the recent institution of newborn screening for T cell deficiencies in many states and earlier recognition of the signs and symptoms of patients with immune deficiency, it is now apparent that PIDD is not as "rare" as was originally thought several decades ago. With the earlier recognition of patients with recurrent infections and various immune perturbations, advancements in the treatment of these immune deficiency disorders have led to enhanced survival and quality of life. In this issue, the diagnosis of PIDD through laboratory testing and skin manifestations is reviewed. The more recently described cellular immune deficiencies, selective immune deficiencies, and advances in the use of bone marrow transplantation in the correction of some of these immune deficiencies are discussed.

Newborn screening for SCID: where are we now?

Newborn screening (NBS) for severe T-cell lymphopenia/severe combined immunodeficiency using the T-cell receptor excision circle assay continues to expand in the USA and worldwide. Here, we will review why severe combined immunodeficiency is an excellent case for NBS, the outcomes of the first 6 years of screening, and dilemmas surrounding screening and management of infants detected by NBS. We will also discuss the future of NBS for primary immunodeficiencies.

Hizentra for the treatment of primary immunodeficiency

Immunoglobulin (IgG) replacement therapy has been the cornerstone of treatment for primary immunodeficiency disease for nearly 60 years. During this time, research has continually refined the target IgG trough level and IgG replacement dosages to allow patients with primary immunodeficiency disease to achieve effective protection from infection. Manufacturers have also improved IgG formulations to allow patients to receive clinically beneficial dosages of IgG replacement with improved safety and tolerability. This review will introduce Hizentra(®), a highly concentrated (20%) IgG solution for subcutaneous (sc.) infusion, discuss its manufacturing process and pharmacokinetic profile and review its tolerability and efficacy data as evaluated in clinical trials. New highly concentrated sc. IgG products may improve patient quality of life and adherence to therapy because of the flexible dosing options, fewer infusion sites and less infusion time, compared with less concentrated sc. IgG products, resulting in favorable patient outcomes consistent with higher steady-state IgG levels.

Autoimmune and other cytopenias in primary immunodeficiencies: pathomechanisms, novel differential diagnoses, and treatment

Autoimmunity and immune dysregulation may lead to cytopenia and represent key features of many primary immunodeficiencies (PIDs). Especially when cytopenia is the initial symptom of a PID, the order and depth of diagnostic steps have to be performed in accordance with both an immunologic and a hematologic approach and will help exclude disorders such as systemic lupus erythematosus, common variable immunodeficiency, and autoimmune lymphoproliferative syndromes, hemophagocytic disorders, lymphoproliferative diseases, and novel differential diagnoses such as MonoMac syndrome (GATA2 deficiency), CD27 deficiency, lipopolysaccharide-responsive beige-like anchor (LRBA) deficiency, activated PI3KD syndrome (APDS), X-linked immunodeficiency with magnesium defect (MAGT1 deficiency), and others. Immunosuppressive treatment often needs to be initiated urgently, which impedes further relevant immunologic laboratory analyses aimed at defining the underlying PID. Awareness of potentially involved disease spectra ranging from hematologic to rheumatologic and immunologic disorders is crucial for identifying a certain proportion of PID phenotypes and genotypes among descriptive diagnoses such as autoimmune hemolytic anemia, chronic immune thrombocytopenia, Evans syndrome, severe aplastic anemia/refractory cytopenia, and others. A synopsis of pathomechanisms, novel differential diagnoses, and advances in treatment options for cytopenias in PID is provided to facilitate multidisciplinary management and to bridge different approaches.

[Humoral immunodeficiency : awareness for better support]

Les déficits immunitaires humoraux (DIH) sont des maladies hétérogènes allant des formes asymptomatiques rencontrés lors des déficits sélectifs en immunoglobulines A (IgA) et en sous-classes d'IgG aux formes graves des agammaglobulinémies congénitales. Les patients atteints de DIH présentent souvent des infections ORL ou des voies respiratoires récidivantes ou sévères. Ces patients peuvent présenter un certain nombre de complications non infectieuses, telles que des manifestations auto-immunes et des entéropathies, qui pourraient être le seul symptôme clinique révélateur. Les formes sévères des DIH sont facilement diagnostiquées grâce au dosage des IgG totaux, des IgA et des IgM. La thérapie substitutive par les immunoglobulines reste le traitement de choix chez ces patients.

Inborn errors of metabolism underlying primary immunodeficiencies

A number of inborn errors of metabolism (IEM) have been shown to result in predominantly immunologic phenotypes, manifesting in part as inborn errors of immunity. These phenotypes are mostly caused by defects that affect the (i) quality or quantity of essential structural building blocks (e.g., nucleic acids, and amino acids), (ii) cellular energy economy (e.g., glucose metabolism), (iii) post-translational protein modification (e.g., glycosylation) or (iv) mitochondrial function. Presenting as multisystemic defects, they also affect innate or adaptive immunity, or both, and display various types of immune dysregulation. Specific and potentially curative therapies are available for some of these diseases, whereas targeted treatments capable of inducing clinical remission are available for others. We will herein review the pathogenesis, diagnosis, and treatment of primary immunodeficiencies (PIDs) due to underlying metabolic disorders.