Differentiation of Common Variable Immunodeficiency From IgG Deficiency

IPINeT Ped-unPAD Study: Goals, Design, and Preliminary Results

Background: An unclassified primary antibody deficiency (unPAD) is a widely heterogeneous clinical entity, recently identified within the spectrum of Inborn Errors of Immunity (IEIs). Since unPAD has been traditionally considered as a mild condition, it has incorrectly received little attention, resulting in the paucity of extensive and comparable studies describing its natural history. To address the gaps in characterizing, understanding, and managing pediatric unPAD patients, the Italian Primary Immunodeficiency Network (IPINet) Ped-unPAD study has recently been launched. Methods: Seventeen IPINeT Centers have expressed interest to participate, and data collection is still on-going. Hereby, we anticipate preliminary key issues emerging from the first 110 enrolled patients, attending three IPINet Centers. Results: A proportion of unPAD patients have experienced a severe infectious phenotype, which required hospitalization in a quarter of patients and antibiotic prophylaxis or Immunoglobulin Replacement Therapy in approximately 10% of patients. In this partial cohort, a mean follow-up (FU) of 5 years confirmed unPAD diagnosis in fifty percent of cases, with the remaining being reclassified as the Transient Hypogammaglobulinemia of Infancy (25%) and other IEIs (25%), such as a Common Variable Immunodeficiency, Selective IgA deficiency, Selective IgM deficiency, and IgG3 subclass deficiency. Conclusions: Despite a phenotype overlap at diagnosis, clinicians should be aware that unPAD is a mutable condition that deserves comprehensive evaluation and long-term monitoring to dissect the final diagnosis for optimal treatment.

Interstitial lung diseases (ILD) in common variable immunodeficiency (CVID) patients: a study from Iran

INTRODUCTION

Interstitial lung disease (ILD) is a prevalent complication in patients with common variable immunodeficiency (CVID) and is often related to other characteristics such as bronchiectasis and autoimmunity. Because the term ILD encompasses a variety of acute and chronic pulmonary conditions, diagnosis is usually based on imaging features. Histopathology is less available. This study was conducted with the aim of investigating the ILD in patients with CVID.

MATERIALS AND METHODS

In this retrospective cross-sectional study, sixty CVID patients who referred to the pulmonology and immunodeficiency clinics of Mofid Children's Hospital between 2013 and 2022 were included. The diagnosis of ILD were based on transbronchial lung biopsy (TBB) or clinical and radiological symptoms. The prevalence of ILD in CVID patients was determined. Also, the CVID patients with and without ILD were compared in terms of demographic characteristics, clinical, laboratory and radiologic findings.

RESULTS

Among all patients, ten patients had ILD (16.6%). In terms of laboratory parameters, there was a significant difference between platelets in the two groups of CVID patients with and without ILD, and the level of platelets was higher in the group of patients with ILD. Moreover, in terms of clinical symptoms, pneumonia, diarrhea and hepatomegaly were significantly different between the two groups and were statistically higher in the group of patients with ILD (P < 0.05). Autoimmunity and malignancy were not significantly different in two groups. There was a significant difference in, hyperinflation between the two groups of CVID patients with and without ILD, and the frequency of, hyperinflation was higher in the patients without ILD (P = 0.040).

CONCLUSION

Understanding the pathogenesis of ILD plays an essential role in revealing non-infectious pulmonary complications that occur in CVID patients. Increasing efforts to understand ILD not only shed light on its hidden pathogenesis and clinical features, but also enhance our understanding of CVID in a broader sense.

A Nationwide Study of the Delayed Diagnosis and the Clinical Manifestations of Predominantly Antibody Deficiencies and CTLA4-Mediated Immune Dysregulation Syndrome in Greece

Background and Objectives: Predominantly antibody deficiencies (PAD) represent the most common type of primary immunodeficiencies in humans, characterized by a wide variation in disease onset, clinical manifestations, and outcome. Considering that the prevalence of PAD in Greece is unknown, and there is limited knowledge on the clinical and laboratory characteristics of affected patients, we conducted a nationwide study. Materials and Methods: 153 patients (male/female: 66/87; median age: 43.0 years; range: 7.0-77.0) diagnosed, and followed-up between August 1979 to September 2023. Furthermore, we classified our cohort into five groups according to their medical history, immunoglobulin levels, and CTLA4-mutational status: 123 had common variable immunodeficiency (CVID), 12 patients with "secondary" hypogammaglobulinemia due to a previous B-cell depletion immunotherapy for autoimmune or malignant disease several years ago (median: 9 years, range 6-14) displaying a typical CVID phenotype, 7 with combined IgA and IgG subclass deficiencies, 5 patients with CVID-like disease due to CTLA4-mediated immune dysregulation syndrome, and 6 patients with unclassified hypogammaglobulinemia. Results: We demonstrated a remarkable delay in PAD diagnosis, several years after the onset of related symptoms (median: 9.0 years, range: 0-43.0). A family history of PAD was only present in 11.8%, with the majority of patients considered sporadic cases. Most patients were diagnosed in the context of a diagnostic work-up for recurrent infections, or recurrent/resistant autoimmune cytopenias. Interestingly, 10 patients (5.6%) had no history of infection, diagnosed due to either recurrent/resistant autoimmunity, or during a work-up of their medical/family history. Remarkable findings included an increased prevalence of lymphoproliferation (60.1%), while 39 patients (25.5%) developed bronchiectasis, and 16 (10.5%) granulomatous disease. Cancer was a common complication in our cohort (25 patients, 16.3%), with B-cell malignancies representing the most common neoplasms (56.7%). Conclusion: Our findings indicate the necessity of awareness about PAD and their complications, aiming for early diagnosis and the appropriate management of affected patients.

In Vivo Antiviral Efficacy of LCTG-002, a Pooled, Purified Human Milk Secretory IgA product, Against SARS-CoV-2 in a Murine Model of COVID-19

Immunoglobulin A (IgA) is the most abundant antibody (Ab) in human mucosal compartments including the respiratory tract, with the secretory form of IgA (sIgA) being dominant and uniquely stable in these environments. sIgA is naturally found in human milk, which could be considered a global resource for this biologic, justifying the development of human milk sIgA as a dedicated airway therapeutic for respiratory infections such as SARS-CoV-2. In the present study, methods were therefore developed to efficiently extract human milk sIgA from donors who were either immunologically naïve to SARS-CoV-2 (pooled as a control IgA) or had recovered from a PCR-confirmed SARS-CoV-2 infection that elicited high-titer anti-SARS-CoV-2 Spike sIgA Abs in their milk (pooled together to make LCTG-002). Mass spectrometry determined that proteins with a relative abundance of 1.0% or greater were all associated with sIgA. None of the proteins exhibited statistically significant differences between batches. Western blot demonstrated all batches consisted predominantly of sIgA. Compared to control IgA, LCTG-002 demonstrated significantly higher binding to Spike, and was also capable of blocking the Spike - ACE2 interaction in vitro with 6.3x greater potency compared to control IgA (58% inhibition at ∼240ug/mL). LCTG-002 was then tested in vivo for its capacity to reduce viral burden in the lungs of K18+hACE2 transgenic mice inoculated with SARS-CoV-2. LCTG-002 was demonstrated to significantly reduce SARS-CoV-2 titers in the lungs compared to control IgA when administered at either 250ug/day or 1 mg/day, as measured by TCID50, plaque forming units (PFU), and qRT-PCR, with a maximum reduction of 4.9 logs. This innovative study demonstrates that LCTG-002 is highly pure, efficacious, and well tolerated in vivo, supporting further development of milk-derived, polyclonal sIgA therapeutics against SARS-CoV-2 and other mucosal infections.

Low and high serum IgG associates with respiratory infections in a young and working age population

BACKGROUND

We investigated health consequences and genetic properties associated with serum IgG concentration in a young and working age general population.

METHODS

Northern Finland Birth Cohort 1966 (NFBC1966, n = 12,231) health data have been collected from birth to 52 years of age. Relationships between life-long health events, medications, chronic conditions, lifestyle, and serum IgG concentration measured at age 46 years (n = 5430) were analysed. Regulatory mechanisms of serum IgG concentration were considered.

FINDINGS

Smoking and genetic variation (FCGR2B and TNFRSF13B) were the most important determinants of serum IgG concentration. Laboratory findings suggestive of common variable immunodeficiency (CVID) were 10-fold higher compared to previous reports (73.7 per 100,000 vs 0.6-6.9 per 100,000). Low IgG was associated with antibiotic use (relative risk 1.285, 95% CI 1.001-1.648; p = 0.049) and sinus surgery (relative risk 2.257, 95% CI 1.163-4.379; p = 0.016). High serum IgG was associated with at least one pneumonia episode (relative risk 1.737, 95% CI 1.032-2.922; p = 0.038) and with total number of pneumonia episodes (relative risk 2.167, 95% CI 1.443-3.254; p < 0.001).

INTERPRETATION

CVID-like laboratory findings are surprisingly common in our unselected study population. Any deviation of serum IgG from normal values can be harmful; both low and high serum IgG may indicate immunological insufficiency. Critical evaluation of clinical presentation must accompany immunological laboratory parameters.

FUNDING

Oulu University Hospital VTR, CSL Behring, Foundation for Pediatric Research.

Activated PI3Kδ syndrome - reviewing challenges in diagnosis and treatment

Activated PI3Kδ syndrome (APDS) is a rare inborn error of immunity (IEI) characterized primarily by frequent infections, lymphoproliferation and autoimmunity. Since its initial description in 2013, APDS has become part of the growing group of nearly 500 IEIs affecting various components of the immune system. The two subtypes of APDS - APDS1 and APDS2 - are caused by variants in the PIK3CD and PIK3R1 genes, respectively. Due to the rarity of the disease and the heterogeneous clinical picture, many patients are not diagnosed until years after symptom onset. Another challenge is the large number of PIK3CD and PIK3R1 variants whose functional significance for developing APDS is inconclusive. Treatment of APDS has so far been mostly symptom-oriented with immunoglobulin replacement therapy, immunosuppressive therapies and antibiotic or antiviral prophylaxes. Additionally, allogeneic stem cell transplantation as well as new targeted therapies are options targeting the root cause that may improve patients' quality of life and life expectancy. However, the clinical course of the disease is difficult to predict which complicates the choice of appropriate therapies. This review article discusses diagnostic procedures and current and future treatment options, and highlights the difficulties that physicians, patients and their caretakers face in managing this complex disease. This article is based on cohort studies, the German and US guidelines on the management of primary immunodeficiencies as well as on published experience with diagnosis and compiled treatment experience for APDS.

The Evolutionary Scenario of Pediatric Unclassified Primary Antibody Deficiency to Adulthood

BACKGROUND

Unclassified primary antibody deficiency (unPAD) is a relatively novel inborn error of immunity (IEI) condition that can vary with time to more defined entities. Since long-term follow-up (FU) studies are scarce, we aimed to provide insight into the evolutionary clinical and immunological scenario of unPAD children to adulthood and identification of biomarkers of primary immune deficiency (PID) persistence.

METHODS

A total of 23 pediatric unPAD patients underwent clinical and immunological FU for a mean time of 14 years (range 3-32 years, median 16 years).

RESULTS

UnPAD diagnosis may change over time. At the last FU, 10/23 (44%) children matched the diagnosis of transient hypogammaglobulinemia of infancy and 13/23 (56%) suffered from a persistent PID. In detail, an unPAD condition was confirmed in 7/23 (30%) patients, whereas 3/23 (13%), 2/23 (9%), and 1/23 (4%) were reclassified as common variable immunodeficiency, selective IgA deficiency, and isolated IgM deficiency, respectively. Low IgA, low specific antibody response to pneumococcus, and lower respiratory tract infections at diagnosis were independently associated with IEI persistence.

CONCLUSIONS

Long-term monitoring of unPAD patients is required to define their outcome and possible evolution towards a definitive IEI diagnosis.

CTLA4 protects against maladaptive cytotoxicity during the differentiation of effector and follicular CD4+ T cells

As chronic antigenic stimulation from infection and autoimmunity is a feature of primary antibody deficiency (PAD), analysis of affected patients could yield insights into T-cell differentiation and explain how environmental exposures modify clinical phenotypes conferred by single-gene defects. CD57 marks dysfunctional T cells that have differentiated after antigenic stimulation. Indeed, while circulating CD57⁺ CD4⁺ T cells are normally rare, we found that they are increased in patients with PAD and markedly increased with CTLA4 haploinsufficiency or blockade. We performed single-cell RNA-seq analysis of matched CD57⁺ CD4⁺ T cells from blood and tonsil samples. Circulating CD57⁺ CD4⁺ T cells (CD4cyt) exhibited a cytotoxic transcriptome similar to that of CD8⁺ effector cells, could kill B cells, and inhibited B-cell responses. CTLA4 restrained the formation of CD4cyt. While CD57 also marked an abundant subset of follicular helper T cells, which is consistent with their antigen-driven differentiation, this subset had a pre-exhaustion transcriptomic signature marked by TCF7, TOX, and ID3 expression and constitutive expression of CTLA4 and did not become cytotoxic even after CTLA4 inhibition. Thus, CD57⁺ CD4⁺ T-cell cytotoxicity and exhaustion phenotypes are compartmentalised between blood and germinal centers. CTLA4 is a key modifier of CD4⁺ T-cell cytotoxicity, and the pathological CD4cyt phenotype is accentuated by infection.

Assessment of low immunoglobulin levels and clinical manifestations in patients with mastocytosis

Background

Patients with a low IgG level alone or with low IgA or IgM levels have been reported to be susceptible to respiratory tract infections and recurrent sinusitis. Patients diagnosed with CVID have a higher prevalence of autoimmune diseases and lymphoid malignancies. Mastocytosis is a myeloproliferative disease, not typically associated with autoimmune disease or frequent infections.

Objective

We sought to determine the distribution of immunoglobulins in children and adults with mastocytosis. Evaluate the impact of low immunoglobulins on the clinical management of patients with mastocytosis.

Methods

We performed a 10-year retrospective analysis on 320 adult and pediatric patients with mastocytosis for immunoglobulins using an electronic medical query. We identified 25 adults and 9 children with one or more low immunoglobulins. Patient records were examined for a history of infections and autoimmune disorders.

Results

Serum immunoglobulins in children and adults with mastocytosis fell within a normal range. Among patients with low IgG levels alone or with low IgM and /or IgA, 20% had a history of infections and 20% of adults had autoimmune disorders. The most common infection was recurrent otitis media (OM).

Conclusion

Patients with mastocytosis typically have normal immunoglobulins. With few exceptions, those with low immunoglobulins did not have frequent infections or autoimmune diseases. This data supports the conclusion that routine determination of immunoglobulins in patients with mastocytosis is not required and reserved for patients with clinical conditions, which might be related to an immunoglobulin deficiency.

Defining Clinical and Immunological Predictors of Poor Immune Responses to COVID-19 mRNA Vaccines in Patients with Primary Antibody Deficiency

Immune responses to coronavirus disease 2019 (COVID-19) mRNA vaccines in primary antibody deficiencies (PADs) are largely unknown. We investigated antibody and CD4+ T-cell responses specific for SARS-CoV-2 spike protein (S) before and after vaccination and associations between vaccine response and patients' clinical and immunological characteristics in PADs. The PAD cohort consisted of common variable immune deficiency (CVID) and other PADs, not meeting the criteria for CVID diagnosis (oPADs). Anti-S IgG, IgA, and IgG subclasses 1 and 3 increased after vaccination and correlated with neutralization activity in HCs and patients with oPADs. However, 42% of CVID patients developed such responses after the 2nd dose. A similar pattern was also observed with S-specific CD4+ T-cells as determined by OX40 and 4-1BB expression. Patients with poor anti-S IgG response had significantly lower levels of baseline IgG, IgA, CD19+ B-cells, switched memory B-cells, naïve CD8+ T-cells, and a higher frequency of EM CD8+ T-cells and autoimmunity compared to patients with adequate anti-S IgG responses. Patients with oPADs can develop humoral and cellular immune responses to vaccines similar to HCs. However, a subset of CVID patients exhibit impairment in developing such responses, which can be predicted by the baseline immune profile and history of autoimmunity.

Turning walking pneumonia into recurrent abscesses: a curious case of CVID and review of the literature

Background

Common variable immunodeficiency (CVID) is a primary immunodeficiency disorder associated with a broad symptom presentation that is still being characterized. We report a rare case of recurrent mycoplasma skin abscesses in a patient with a history of autoimmune disorders and prolonged mycoplasma pneumonia who was diagnosed with CVID.

Case presentation

A 34-year-old woman presented with a history of recurrent abscesses previously confirmed positive for Mycoplasma pneumoniae. Her past medical history of recurrent mycoplasma abscesses, prolonged mycoplasma pneumonia, and autoimmune disorders (mixed connective tissue disease and immune thrombocytopenia) raised suspicion of CVID. Workup included negative anti-mycoplasma antibody titers, hypogammaglobulinemia, and negative anti-pneumococcal antibody titers despite prior vaccination, solidifying the diagnosis of CVID. The patient was discharged on antibiotic and intravenous immunoglobulin therapy and now follows allergy and immunology long-term for treatment.

Conclusions

Her diagnostic history underscores the importance of considering the various criteria of CVID for diagnosis, and her unique presentation of M. pneumoniae skin abscesses highlights the broad sequelae patients with CVID can manifest.

Protocol for the unclassified primary antibody deficiency (unPAD) study: Characterization and classification of patients using the ESID online Registry

Background

Primary antibody deficiencies (PADs) without an identified monogenetic origin form the largest and most heterogeneous group of primary immunodeficiencies. These patients often remain undiagnosed for years and many present to medical attention in adulthood after several infections risking structural complications. Not much is known about their treatment, comorbidities, or prognosis, nor whether the various immunological forms (decreased total IgG, IgG subclass(es), IgM, IgA, specific antibody responses, alone or in combination(s)) should be considered as separate, clearly definable subgroups. The unclassified primary antibody deficiency (unPAD) study aims to describe in detail all PAD patients without an identified specific monogenetic defect regarding their demographical, clinical, and immunological characteristics at presentation and during follow-up. In constructing these patterns, the unPAD study aims to reduce the number of missed and unidentified PAD patients in the future. In addition, this study will focus on subclassifying unPAD to support the identification of patients at higher risk for infection or immune dysregulation related complications, enabling the development of personalized follow-up and treatment plans.

Methods and analysis

We present a protocol for a multicenter observational cohort study using the ESID online Registry. Patients of all ages who have given informed consent for participation in the ESID online Registry and fulfill the ESID Clinical Working Definitions for ‘unclassified antibody deficiency’, ‘deficiency of specific IgG’, ‘IgA with IgG subclass deficiency’, ‘isolated IgG subclass deficiency’, ‘selective IgM deficiency’, ‘selective IgA deficiency’ or ‘common variable immunodeficiency’ will be included. For all patients, basic characteristics can be registered at first registration and yearly thereafter in level 1 forms. Detailed characteristics of the patients can be registered in level 2 forms. Consecutive follow-up forms can be added indefinitely. To ensure the quality of the collected data, all data will be fully monitored before they are exported from the ESID online Registry for analysis. Outcomes will be the clinical and immunological characteristics of unPAD at presentation and during follow-up. Subgroup analyses will be made based on demographical, clinical and immunological characteristics.

Immunological evaluation of patients with orthopedic infections: taking the Cierny-Mader classification to the next level

Introduction: Cierny–Mader osteomyelitis classification is used to label A, B, or C hosts based on comorbidities. This study's purpose was to define the “true” host status of patients with orthopedic infection using serologic markers to quantify the competence of their immune system while actively infected. Methods: Retrospective chart review identified patients at a single-surgeon practice who were diagnosed with orthopedic infection between September 2013 and March 2020 and had immunological laboratory results. All patients were A or B hosts who underwent surgery to eradicate infection. Medical history, physical examination, and Cierny–Mader classification were recorded. Laboratory results included complement total, C3, C4, immunoglobulin G (IgG), immunoglobulin M (IgM), immunoglobulin A (IgA), immunoglobulin E (IgE), rheumatoid factor, and antineutrophil cytoplasmic antibodies (ANCA) panel. Clinically significant results were defined as flagged abnormal. Normal complement levels and normal IgG levels were considered abnormal when infection was present. Results: Of 105 patients, 99 (94 %) had documented lab abnormalities. Clinically significant abnormalities were found in 33 of 34 (97 %) type-A hosts and 66 of 71 (93 %) type-B hosts. Eleven of 105 (10.5 %) patients were formally diagnosed with primary immunodeficiency by a hematologist. IgG deficiency, of either low or normal value, in the face of infection comprised 91 % (30 of 34) type-A hosts and 86 % (56 of 71) type-B hosts. Six (5.7 %) patients received IgG replacement therapy. Twenty-eight patients had abnormal total complement levels (low or normal): 7.4 % (2 of 34) A hosts and 40 % (26 of 71) B hosts (p=0.002). B hosts had statistically significantly lower complement levels and significantly more no-growth cultures (p<0.03). Thirteen of 14 patients with recurrent infections had low or normal IgG levels. IgM was significantly lower between reinfected patients and those without reinfection (p=0.0005). Conclusions: Adding immunologic evaluation to the Cierny–Mader classification more accurately determines patients' true host status and better quantifies risk and outcome with respect to orthopedic infection. Immunologically deficient A hosts should be quantified as B hosts. IgG deficiencies may be addressed when deemed appropriate by the consulting hematologist/immunologist. Patients with recurrent infections had significantly lower IgM levels than their nonrecurrent infection counterparts.

Lymphoid malignancy in common variable immunodeficiency in a single-center cohort

One of the complications of common variable immunodeficiency (CVID) is the development of lymphoid malignancy. In this retrospective, single-center study of 647 CVID subjects followed over 4 decades, we present immunologic and clinical phenotypes, pathology, treatment, and outcomes of 45 patients (15 males and 30 females, 7%) who developed 49 lymphoid malignancies. The mean age at CVID diagnosis was 42.6 years) and at lymphoma diagnosis was 48.8 years. Of the 41 with known follow up, 29 (70%) have died, 27 of these due to this diagnosis. Twelve are alive, in remission or have achieved cure; four others were alive at last encounter. Some patients had a history of only recurrent infections (36.3%); others had autoimmunity (33%), enteropathy (20%), and/or granulomatous disease (11%). Six had previously been treated for another cancer. This report also includes 6 additional living CVID patients who had been diagnosed with NHL; 4 were given treatment for this. However, on pathology review, the initial diagnosis was reversed, as the findings were more consistent with a benign lymphoproliferative process. This study outlines the high incidence of lymphoma in this single CVID cohort, and some of the diagnostic challenges presented due to immune dysregulation characteristic of this immune defect.

Humoral Immune Deficiencies of Childhood

The most common primary immune deficiencies are those of the humoral immune system, and most of these present in childhood. The severity of these disorders ranges from transient deficiencies to deficiencies that are associated with a complete loss of ability to make adequate or functional antibodies, and have infectious as well as noninfectious complications. This article reviews, in a case-based discussion, the most common of the humoral immune deficiencies; their presentations, diagnoses, treatments; and, when known, the genetic defects.

Antibody Deficiency, Chronic Lung Disease, and Comorbid Conditions: A Case-Based Approach

New emerging pulmonary phenotypes associated with antibody deficiency, such as neutrophilic asthma, frequent exacerbations of chronic obstructive pulmonary disease, and unexplained interstitial lung disease, particularly in younger adults, are discussed in this review through a case-based approach. Also discussed in similar fashion are antibody deficiency syndromes that lead to end-stage lung disease and the indications for lung transplantation in primary immunodeficiency disease. These challenging cases require timely and individualized strategies for genetic and immunologic diagnosis, decisions about therapeutic approaches, and long-term monitoring.

Spectrum of Disease Manifestations in Patients with Selective Immunoglobulin E Deficiency

BACKGROUND

Selective IgE deficiency (SIgED) has been previously evaluated in selected patients from allergy units. This study investigates the effects of SIgED on the entire population in a hospital setting and sought to delineate in detail the clinical aspects of SIgED.

METHODS

A retrospective study of the data obtained from electronic medical records of 52 adult patients (56% female) with a mean age of 43 years and IgE levels of <2.0 kU/L with normal immunoglobulin (Ig) IgG, IgA, and IgM levels, seen at our hospital, without selection bias, from 2010 to 2019.

RESULTS

Recurrent upper respiratory infections were recorded in 18 (34.6%) patients, pneumonia was recorded in 16 (30.7%) patients, bronchiectasis was recorded in 16 (30.7%) patients, and asthma was recorded in 10 (19.2%) patients. Eighteen patients (34.6%) suffered autoimmune clinical manifestations either isolated (19%) or combining two or more diseases (15%), Hashimoto's thyroiditis being the most frequent (19%), which was followed by arthritis (10%) and thrombocytopenia and/or neutropenia (5.7%). Other less frequent associations were Graves' disease, primary sclerosing cholangitis, Sjögren's syndrome, and autoimmune hepatitis. Eczematous dermatitis (15.3%), chronic spontaneous urticaria (17.3%), and symptoms of enteropathy (21%) were also highly prevalent. Thirty percent of patients developed malignancies, with non-Hodgkin lymphomas (13.4%) being the most prevalent.

CONCLUSIONS

The clinical manifestations of SIgED encompass a variety of infectious, non-infectious complications, and malignancy. Since it cannot be ruled out that some type of selection bias occurred in the routine assessment of IgE serum Ievels, prospective studies are required to better characterize SIgED and to determine whether it should be added to the list of antibody deficiencies.

An enzyme-linked immunospot assay to evaluate Pneumovax response when on intravenous immunoglobulin

BACKGROUND

Testing for common variable immunodeficiency (CVID) requires evaluation of specific antibody responses to vaccines. Current practice of evaluating pneumococcal serotype-specific immunoglobulin (Ig)G levels after Pneumovax (P23) has several limitations and is not accurate for patients already on immunoglobulin replacement. In contrast, the enzyme-linked immunospot (ELISPOT) assay can be interpreted in patients on immunoglobulin replacement as ex vivo measurement of specific antibody-secreting cells (ASCs).

OBJECTIVE

To optimize and test an ELISPOT assay to evaluate vaccination response to P23 and compare with P23 serotype-specific IgG for patients on intravenous immunoglobulin (IVIG).

METHODS

We prospectively enrolled a total of 15 adults: normal controls (n = 8), patients with CVID on IVIG replacement (n = 2), patients on IVIG replacement for recurrent infections who did not meet diagnostic criteria for CVID, considered IgG deficiency (n = 2), and patients without immunodeficiency on high-dose IVIG for other diagnosis (n = 3). We measured P23 serotype-specific IgG before and 4 weeks after P23 and ELISPOT ASCs before and 1 week after P23 (with B-cell subpopulation analysis by flow cytometry in patients on IVIG).

RESULTS

Normal controls had a vaccination response by P23 serotype-specific IgG, whereas patients on IVIG did not. Except for true patients with CVID on IVIG, a P23 ELISPOT ASC response was found in normal controls (highest) and most patients on IVIG for recurrent infections or other diagnosis.

CONCLUSION

Our pilot study suggests that an optimized ELISPOT protocol has utility to evaluate the P23-specific antibody response after vaccination. Our ELISPOT assay seemed reliable for patients on IVIG and may help differentiate true patients with CVID from those with a less stringent diagnosis while on IVIG.

Lessons Learned From the Clinical Presentation of Common Variable Immunodeficiency Disorders: A Systematic Review and Meta-Analysis

Background

Diagnostic delay in common variable immunodeficiency disorders (CVID) is considerable. There is no generally accepted symptom-recognition framework for its early detection.

Objective

To systematically review all existing data on the clinical presentation of CVID.

Methods

PubMed, EMBASE and Cochrane were searched for cohort studies, published January/1999-December/2019, detailing the clinical manifestations before, at and after the CVID-diagnosis.

Results

In 51 studies (n=8521 patients) 134 presenting and 270 total clinical manifestations were identified. Recurrent upper and/or lower respiratory infections were present at diagnosis in 75%. Many patients had suffered severe bacterial infections (osteomyelitis 4%, meningitis 6%, septicemia 8%, mastoiditis 8%). Bronchiectasis (28%), lymphadenopathy (27%), splenomegaly (13%), inflammatory bowel disease (11%), autoimmune cytopenia (10%) and idiopathic thrombocytopenia (6%) were also frequently reported. A bimodal sex distribution was found, with male predominance in children (62%) and female predominance in adults (58%). 25% of CVID-patients developed other manifestations besides infections in childhood, this percentage was much higher in adults (62%). Immune-dysregulation features, such as granulomatous-lymphocytic interstitial lung disease and inflammatory bowel disease, were more prominent in adults.

Conclusions

The shift from male predominance in childhood to female predominance in adults suggests differences in genetic and environmental etiology in CVID and has consequences for pathophysiologic studies. We confirm the high frequency of respiratory infections at presentation, but also show a high incidence of severe bacterial infections such as sepsis and meningitis, and immune dysregulation features including lymphoproliferative, gastrointestinal and autoimmune manifestations. Early detection of CVID may be improved by screening for antibody deficiency in patients with these manifestations.

Interstitial Lung Disease in Common Variable Immunodeficiency

Interstitial lung disease (ILD) is a common complication in patients with common variable immunodeficiency (CVID) and often associated with other features, such as bronchiectasis and autoimmunity. As the ILD term encompasses different acute and chronic pulmonary conditions, the diagnosis is commonly made based on imaging features; histopathology is less frequently available. From a cohort of 637 patients with CVID followed at our center over 4 decades, we reviewed the data for 46 subjects (30 females, 16 males) who had lung biopsies with proven ILD. They had a median age at CVID diagnosis of 26 years old, with a median IgG level at diagnosis of 285.0 mg/dL with average isotype switched memory B cells of 0.5%. Lung biopsy pathology revealed granulomas in 25 patients (54.4%), lymphoid interstitial pneumonia in 13 patients (28.3%), lymphoid hyperplasia not otherwise specified in 7 patients (15.2%), cryptogenic organizing pneumonia in 7 patients (15.2%), follicular bronchitis in 4 patients (8.7%), and predominance of pulmonary fibrosis in 4 patients (8.7%). Autoimmune manifestations were common and were present in 28 (60.9%) patients. Nine patients (19.6%) died, with a median age at death of 49-years-old. Lung transplant was done in 3 of these patients (6.5%) who are no longer alive. These analyses reveal the high burden of this complication, with almost one-fifth of the group deceased in this period. Further understanding of the causes of the development and progression of ILD in CVID patients is required to define the best management for this patient population.

Perspective: Evolving Concepts in the Diagnosis and Understanding of Common Variable Immunodeficiency Disorders (CVID)

Common variable immunodeficiency disorders (CVID) are the most frequent symptomatic primary immune deficiency in adults. At this time, the causes of these conditions are unknown. Patients with CVID experience immune system failure consequent to late onset antibody failure. They have increased susceptibility to infections and are also at risk of severe autoimmune and inflammatory disorders as a result of immune dysregulation. An increasing number of monogenic causes as well as a digenic disorder have been described in patients with a CVID phenotype. If a causative mutation is identified, patients are removed from the umbrella diagnosis of CVID and are reclassified as having a CVID-like disorder, resulting from a specific mutation. In non-consanguineous populations, next-generation sequencing (NGS) identifies a genetic cause in approximately 25% of patients with a CVID phenotype. It is six years since we published our diagnostic criteria for CVID. There is ongoing debate about diagnostic criteria, the role of vaccine responses and genetic analysis in the diagnosis of CVID. There have been several recent studies, which have addressed some of these uncertainties. Here we review this new evidence from the perspective of our CVID diagnostic criteria and speculate on future approaches, which may assist in identifying and assessing this group of enigmatic disorders.

Current genetic landscape in common variable immune deficiency

Using whole-exome sequencing to examine the genetic causes of immune deficiency in 235 common variable immunodeficiency (CVID) patients seen in the United States (Mount Sinai, New York), 128 patients from Sweden, and 208 from Iran revealed 68 known disease-causing genes underlying this heterogeneous immune defect. The patients at the time of study ranged from 4 to 90 years of age. Overall, 31%, 36%, and 54% of the patients in the US, Swedish, or Iranian cohorts had mutations. The multiplicity of genes identified in the 571 subjects reflects the complex requirements of B-cell antigen signaling, activation, survival, migration, maturation, and maintenance of antibody-secreting memory B-cell populations to the plasma cell stage. For the US and Swedish cohorts, CVID subjects with noninfectious complications, lymphoid infiltrations, inflamatory conditions, or autoimmunity were somewhat more likely to have an identifiable gene, but in both cohorts, numerous subjects with these medical conditions had no potential gene that could be assigned. Specific clinical patterns of illnesses were also not linked to any given gene defect as there was considerable overlap in clinical presentations. These observations led to a new perspective on the complexity of the immunologic phenotype found in CVID syndrome.

Targeting FcRn for immunomodulation: Benefits, risks, and practical considerations

The neonatal fragment crystallizable (Fc) receptor (FcRn) functions as a recycling mechanism to prevent degradation and extend the half-life of IgG and albumin in the circulation. Several FcRn inhibitors selectively targeting IgG recycling are now moving rapidly toward clinical practice in neurology and hematology. These molecules accelerate the destruction of IgG, reducing pathogenic IgG and IgG immune complexes, with no anticipated effects on IgA, IgM, IgE, complement, plasma cells, B cells, or other cells of the innate or adaptive immune systems. FcRn inhibitors have potential for future use in a much wider variety of antibody-mediated autoimmune diseases. Given the imminent clinical use, potential for broader utility, and novel mechanism of action of FcRn inhibitors, here we review data from 4 main sources: (a) currently available activity, safety, and mechanism-of-action data from clinical trials of FcRn inhibitors; (b) other procedures and treatments that also remove IgG (plasma donation, plasma exchange, immunoadsorption); (c) diseases resulting in loss of IgG; and (d) primary immunodeficiencies with potential mechanistic similarities to those induced by FcRn inhibitors. These data have been evaluated to provide practical considerations for the assessment, monitoring, and reduction of any potential infection risk associated with FcRn inhibition, in addition to highlighting areas for future research.

Immunoglobulin G and immunoglobulin G subclass concentrations differ according to sex and race

BACKGROUND

Serum immunoglobulin G (IgG) concentrations are integral to the workup of immune deficiencies and IgG4-related disease (IgG4-RD). Demographic differences in IgG concentrations are poorly described but can influence test interpretation, contribute to racial disparities in primary immunodeficiency diagnosis, and explain demographic differences in IgG concentrations in IgG4-RD.

OBJECTIVE

To assess differences in IgG and IgG subclass concentrations according to sex and race.

METHODS

We identified patients with IgG and IgG subclass concentrations measured in a large health care system. Multivariate-adjusted differences in IgG and IgG subclass concentrations and the proportion of subjects with results outside of reference ranges according to sex and race were estimated.

RESULTS

Of the 12,851 patients, the mean age was 54.7 years and 7917 (62%) were female. Of these, 11,673 (91%) were white, 611 (5%) were black, and 302 (2%) were Asian. Compared with the mean concentrations of white patients, Asian and black patients had higher mean concentrations of IgG (1340.0 and 1504.4 vs 988.1 mg/dL, P < .001), IgG1 (782.0 and 938.4 vs 592.4 mg/dL, P < .001), IgG2 (493.5 and 384.2 vs 305 mg/dL, P < .001), IgG3 (76.6 and 91.9 vs 55.9 mg/dL, P < .001), and IgG4 (140.4 and 53.6 vs 41.6 mg/dL, P < .001). Immunoglobin G subclass 4 concentrations were higher in males than those in females (56.3 vs 37.4 mg/dL, P < .001). Similar observations were made when comparing the proportions of patients with results outside of reference ranges and after stratifying by diagnosis.

CONCLUSION

Immunoglobin G and IgG subclass concentrations differ according to sex and race. These findings may have implications for the interpretation of these test results but require confirmation in diverse, healthy populations.

Defining Common Variable Immunodeficiency Disorders in 2020

Common variable immunodeficiency disorders (CVID) are the most frequent symptomatic primary immune deficiency in adults. Because there is no known cause for these conditions, there is no single clinical feature or laboratory test that can confirm the diagnosis with certainty. If a causative mutation is identified, patients are deemed to have a CVID-like disorder caused by a specific primary immunodeficiency/inborn error of immunity. In the remaining patients, the explanation for these disorders remains unclear. The understanding of CVID continues to evolve and the authors review recent studies, which have addressed some of these uncertainties.

Immunological and Clinical Phenotyping in Primary Antibody Deficiencies: a Growing Disease Spectrum

PURPOSE

Although common variable immunodeficiency (CVID) is considered the most prevalent symptomatic primary antibody deficiency (PAD), there is a population with symptomatic PADs that do not meet criteria for CVID. We analyzed clinical and immunological profiles of patients with different PADs to better understand the differences and similarities between CVID and other PADs.

METHODS

We extracted clinical and laboratory data of patients with PADs from electronic medical records. Patients were categorized into CVID, IgG subclass 2 deficiency (IgG2D), IgG deficiency (IgGD), and specific antibody deficiency (sAbD) based on basal immunoglobulin levels and pneumococcal vaccine responses. We compared clinical and immunological characteristics in these groups.

RESULTS

All patients, regardless of PAD types, showed similar frequencies of infections, bronchiectasis, and interstitial lung disease (ILD). Hematopoietic malignancies were more frequently found in the CVID than in the IgG2D, IgGD, and sAbD groups, while the latter groups trended towards an increased frequency of connective tissue diseases (CTD). Low counts of natural killer (NK) cells were associated with malignancy, autoimmunity, and ILD in CVID but not in other PAD groups.

CONCLUSIONS

Higher frequency of hematopoietic malignancy in CVID than in the other PADs and association of lower NK cell counts with non-infectious complications in CVID suggest a relationship between immune alterations and the development of non-infectious manifestations in PADs.

The presence of overlapping quality of life symptoms in primary antibody deficiency (PAD) and chronic fatigue syndrome (CFS)

Background

Fatigue, sleep disturbance and altered mood are frequently reported in patients with primary antibody deficiency syndrome (PADS) on adequate immunoglobulin replacement therapy. This study aimed to determine the frequency of symptoms compatible with chronic fatigue syndrome (CFS) in patients with PADS.

Methods

The study involved the distribution of 682 self-completed postal questionnaires to ascertain the presence and frequency of symptoms compatible with CFS in patients with PADS. The reporting of symptoms for each patient were scored against the CFS diagnostic criteria used within our own South London Chronic Fatigue service.

Results

The frequency of symptoms compatible with CFS were evident in 26 of the 188 patients (16.25%) returning adequately completed questionnaires. We considered a bias in the return of questionnaires amongst PADS patients with fatigue to be likely. As such we estimated the minimum frequency of CFS in patients with PADS to be 4% based on the 682 PAD patients to whom the questionnaire was distributed. This was significantly higher than the 0.5% estimate of the prevalence of CFS in the community in western populations. While the presence of significant fatigue correlated with the presence of anxiety and depression, there was no association with self-reported lung damage. Sleep disturbance affected 60% of the PAD patients returning satisfactory questionnaires and as expected the CFS score was higher in those with greater physical limitation.

Conclusions

We conclude that patients with PADS have a high frequency of fatigue, low mood and anxiety. We suggest routine questioning for the symptoms of fatigue, disturbed sleep and altered mood in patients with PADS. The use of several treatment strategies in CFS may prove beneficial in improving the quality of life of patients with PAD.

Bronchiectasis in common variable immunodeficiency: A systematic review and meta-analysis

BACKGROUND

Common variable immunodeficiency (CVID) is the most prevalent symptomatic primary immunodeficiency disorder characterized by infectious and noninfectious complications. Bronchiectasis continues to be a common respiratory problem and therapeutic challenge in CVID. The aim of this study is to estimate the overall prevalence of bronchiectasis and its associated phenotype in patients with CVID.

METHODS

A systematic literature search was performed in Web of Science, PubMed, and Scopus from the earliest available date to February 2019 with standard keywords. All pooled analyses of bronchiectasis prevalence and the corresponding 95% confidence intervals (CIs) were based on random-effects models.

RESULTS

Fifty-five studies comprising 8535 patients with CVID were included in the meta-analysis. Overall prevalence of bronchiectasis was 34% (95% CI: 30-38; I²  = 90.19%). CVID patients with bronchiectasis had significantly lower serum immunoglobulin A (IgA) and IgM levels at the time of diagnosis compared with those without bronchiectasis. Among the clinical features, the frequencies of splenomegaly, pneumonia, otitis media, and lymphocytic interstitial pneumonia were significantly higher in CVID patients with bronchiectasis compared with those without bronchiectasis, respectively.

CONCLUSION

A higher prevalence of bronchiectasis in patients with CVID should be managed by controlling recurrent and severe pneumonia episodes which are immune dysregulation since this complication is associated with poor prognosis in these patients.

The Journal of Allergy and Clinical Immunology: In Practice 2019 Highlights

This article provides highlights of the clinically impactful original studies and reviews published in The Journal of Allergy and Clinical Immunology: In Practice in 2019 on the subjects of anaphylaxis, asthma, dermatitis, drug allergy, food allergy, immunodeficiency, immunotherapy, rhinitis/sinusitis, and urticaria/angioedema/mast cell disorders. Within each topic, practical aspects of diagnosis and management are emphasized. Treatments discussed include lifestyle modifications, allergen avoidance therapy, positive and negative effects of pharmacologic therapy, and various forms of immunologic and desensitization management. We designed this review to help readers consolidate and use this extensive and practical knowledge for the benefit of their patients.

Making a Diagnosis of Common Variable Immunodeficiency: A Review

Common variable immunodeficiency (CVID) is a condition that inhibits the function of the immune system, making those with the condition more susceptible to infection from external pathogens, including bacteria and, less often, viruses. The immune disorder is marked by low immunoglobulin levels of immunoglobulin G (IgG) and IgA as well as IgM in some patients. These immune abnormalities typically result in recurrent sinopulmonary infections and can result in serious complications such as pneumonia and chronic lung disease. Other manifestations include poor vaccine response and defective antibodies in a patient’s immune system. The disorder affects approximately one in 25,000 to one in 50,000 individuals worldwide, with the condition varying across different populations. While the underlying mechanism of disease activity remains poorly understood, only 10% of cases are known to have an underlying genetic link and approximately 25% of patients also have an autoimmune disorder. CVID commonly presents in individuals in their twenties or thirties but can present at any time between childhood through adulthood, with mortality dependent on the severity of illness and frequency of recurrent infections. Potential life-threatening consequences of CVID include malignancies, enteropathy, and autoimmune manifestations. Treatment can help alleviate symptoms and prevent continued recurrent infections and serious complications. However, the lack of awareness among primary care physicians (PCPs) makes the condition difficult to diagnose and manage. In this review article, we will provide insight into the clinical manifestations as well as the diagnosis and management of CVID. This will provide clinical practitioners with tools to recognize the disease earlier on to improve patient outcomes and prevent serious complications. We will also afford a better understanding of genetic components tied to CVID and new research efforts.

Serum B-Cell Maturation Antigen (BCMA) Levels Differentiate Primary Antibody Deficiencies

BACKGROUND

Primary antibody deficiencies (PADs) are the most prevalent primary immunodeficiencies. More severe forms of PADs-common variable immunodeficiency (CVID) and X-linked agammaglobulinemia (XLA)-require immunoglobulin replacement therapy (IRT) and may have serious complications. Differentiating severe PAD from milder hypogammaglobulinemia not requiring IRT can involve prolonged evaluations and treatment discontinuation. Severe PAD is defined by plasma cell deficiency, but this requires a biopsy to establish. Serum B-cell maturation antigen (sBCMA) is elevated in multiple myeloma, but levels are reduced among patients with myeloma in remission who have hypogammaglobulinemia.

OBJECTIVE

To measure the sBCMA level in 165 subjects to determine whether it differentiates severe PAD-CVID and XLA-from less severe forms not requiring IRT and those without PAD.

METHODS

sBCMA, B cells, and tissue plasma cells were measured among subjects with and without PAD, and correlated to clinical and laboratory data.

RESULTS

Subjects with an IgG level of less than 600 mg/dL had reduced sBCMA levels compared with subjects with PAD with IgG levels of greater than or equal to 600 mg/dL and controls without PAD. sBCMA level was lower in patients with CVID and XLA compared with patients with IgA or IgG deficiency and controls. sBCMA level correlated with gastrointestinal plasma cells. sBCMA level of less than 15 ng/mL had 97% positive predictive value for CVID or XLA, whereas 25 ng/mL or more had an 88% negative predictive value.

CONCLUSIONS

sBCMA level is profoundly reduced in patients with severe PAD, including those with CVID and XLA and those with IgG levels of less than 600 mg/dL. sBCMA level measurement has potential to augment clinical evaluation of PAD. Prospective studies are needed to evaluate sBCMA for new PAD diagnosis and determine the necessity of IRT.

Common variable immune deficiency: case studies

Common variable immune deficiency (CVID) is one of the most common congenital immune defects encountered in clinical practice. The condition occurs equally in males and females, and most commonly in the 20- to 40-year-old age group. The diagnosis is made by documenting reduced serum concentrations of immunoglobulin G (IgG), IgA, and usually IgM, together with loss of protective antibodies. The genetics of this syndrome are complex and are still being unraveled, but the hallmarks for most patients, as with other immune defects, include acute and chronic infections of the sinopulmonary tract. However, other noninfectious autoimmune or inflammatory conditions may also occur in CVID, and indeed these may be the first and only sign that a significant immune defect is present. These manifestations include episodes of immune thrombocytopenia, autoimmune hemolytic anemia, or neutropenia, in addition to splenomegaly, generalized or worrisome lymphadenopathy, and malignancy, especially lymphoma. These issues commonly bring the patient to the attention of hematologists for both evaluation and treatment. This article discusses 3 cases in which patients with CVID had some of these presenting issues and what hematology input was required.

Common variable immune deficiency: case studies

Common variable immune deficiency (CVID) is one of the most common congenital immune defects encountered in clinical practice. The condition occurs equally in males and females, and most commonly in the 20- to 40-year-old age group. The diagnosis is made by documenting reduced serum concentrations of immunoglobulin G (IgG), IgA, and usually IgM, together with loss of protective antibodies. The genetics of this syndrome are complex and are still being unraveled, but the hallmarks for most patients, as with other immune defects, include acute and chronic infections of the sinopulmonary tract. However, other noninfectious autoimmune or inflammatory conditions may also occur in CVID, and indeed these may be the first and only sign that a significant immune defect is present. These manifestations include episodes of immune thrombocytopenia, autoimmune hemolytic anemia, or neutropenia, in addition to splenomegaly, generalized or worrisome lymphadenopathy, and malignancy, especially lymphoma. These issues commonly bring the patient to the attention of hematologists for both evaluation and treatment. This article discusses 3 cases in which patients with CVID had some of these presenting issues and what hematology input was required.

Humoral Immune Deficiencies of Childhood

The most common primary immune deficiencies are those of the humoral immune system, and most of these present in childhood. The severity of these disorders ranges from transient deficiencies to deficiencies that are associated with a complete loss of ability to make adequate or functional antibodies, and have infectious as well as noninfectious complications. This article reviews, in a case-based discussion, the most common of the humoral immune deficiencies; their presentations, diagnoses, treatments; and, when known, the genetic defects.

Appropriate lung management in patients with primary antibody deficiencies

Introduction: Human primary immunodeficiency diseases (PIDs) include a broad spectrum of more than 350 disorders, involving different branches of the immune system and classified as 'rare diseases.' Predominantly antibody deficiencies (PADs) represent more than half of the PIDs diagnosed in Europe and are often diagnosed in the adulthood. Areas covered: Although PAD could first present with autoimmune or neoplastic features, respiratory infections are frequent and respiratory disease represents a relevant cause of morbidity and mortality. Pulmonary complications may be classified as infection-related (acute and chronic), immune-mediated, and neoplastic. Expert opinion: At present, no consensus guidelines are available on how to monitor and manage lung complications in PAD patients. In this review, we will discuss the available diagnostic, prognostic and therapeutic instruments and we will suggest an appropriate and evidence-based approach to lung diseases in primary antibody deficiencies. We will also highlight the possible role of promising new tools and strategies in the management of pulmonary complications. However, future studies are needed to reduce of diagnostic delay of PAD and to better understand lung diseases mechanisms, with the final aim to ameliorate therapeutic options that will have a strong impact on Quality of Life and long-term prognosis of PAD patients.

The Natural History of Untreated Primary Hypogammaglobulinemia in Adults: Implications for the Diagnosis and Treatment of Common Variable Immunodeficiency Disorders (CVID)

Background: Adults with primary hypogammaglobulinemia are frequently encountered by clinicians. Where IgG levels are markedly decreased, most patients are treated with subcutaneous or intravenous immunoglobulin (SCIG/IVIG), because of the presumed risk of severe infections. The natural history of untreated severe asymptomatic hypogammaglobulinemia is thus unknown. Similarly, there are no long-term prospective studies examining the natural history of patients with moderate reductions in IgG.

Methods: In 2006, we began a prospective cohort study of patients with symptomatic and asymptomatic reductions in IgG who were not immediately commenced on SCIG/IVIG. Over the course of 12 years, 120 patients were enrolled in the NZ hypogammaglobulinemia study (NZHS) including 59 who were asymptomatic.

Results: Five patients with profound primary hypogammaglobulinemia (IgG < 3 g/l), who were not on regular SCIG/IVIG have remained well for a mean duration of 139 months. This study has also shown most asymptomatic patients with moderate hypogammaglobulinemia (IgG 3.0–6.9 g/l) have been in good health for a mean observation period of 96 months. We have only identified one asymptomatic patient with moderate hypogammaglobulinemia who experienced progressive decline in IgG levels to <3 g/l and was accepted for IVIG replacement. Prospective monitoring has shown that none have suffered catastrophic infections or any of the severe autoimmune or inflammatory sequelae associated with Common Variable Immunodeficiency Disorders (CVID). Unexpectedly, 18.1% of asymptomatic and 41.6% of symptomatic hypogammaglobulinemic patients spontaneously increased their IgG into the normal range (≥7.0 g/l) on at least one occasion, which we have termed transient hypogammaglobulinemia of adulthood (THA). In this study, vaccine challenge responses have correlated poorly with symptomatic state and long-term prognosis including subsequent SCIG/IVIG treatment.

Conclusions: In spite of our favorable experience, we recommend patients with severe asymptomatic hypogammaglobulinemia are treated with SCIG/IVIG because of the potential risk of severe infections. Patients with moderate asymptomatic hypogammaglobulinemia have a good prognosis. Patients with symptomatic hypogammaglobulinemia are a heterogeneous group where some progress to SCIG/IVIG replacement, while many others spontaneously recover. This study has implications for the diagnosis and treatment of CVID.