Antibody deficiency testing for primary immunodeficiency: A practical review for the clinician

Functional testing of humoral immunity in the Prevnar 20 era

Humoral immune disorders such as common variable immunodeficiency and specific antibody deficiency are prevalent in clinical practice and require accurate functional testing of humoral immunity for diagnosis and to guide treatment approach. Traditionally, the 23-valent pneumococcal polysaccharide vaccine (PPSV23) has been used to assess polysaccharide antibody responses by measuring pre- and post-vaccination pneumococcal titers. However, the recent introduction of pneumococcal conjugate vaccines (PCVs), such as PCV13, PCV15, and PCV20, into the childhood and adult vaccine schedules has significantly reduced the number of unique serotypes available for testing and in turn has complicated the evaluation process. We retrospectively analyzed serotype-specific antibody responses in patients aged 2 to 65 years who received PPSV23 at the University of Virginia Health System to compare diagnostic outcomes using all 23 serotypes vs the limited number of unique serotypes not included in previous PCVs-11 serotypes for PCV13 recipients and 4 for PCV20 recipients. Our findings reveal that although previous PCVs mean that there is a reduced number of serotypes available for interpretation, PPSV23 testing maintains diagnostic accuracy between 81% and 84%. Despite limitations, the use of PPSV23 remains a valuable tool for identifying patients with clinically significant humoral immune deficiencies. In the future, alternative diagnostic approaches such as Salmonella typhi polysaccharide vaccine response and opsonophagocytosis assays may become more frequently used as part of the evaluation of humoral immune disorders.

Inborn errors of immunity (primary immunodeficiencies)

Primary immunodeficiencies (PID), now often referred to as inborn errors of immunity (IEI), are a large heterogeneous group of disorders that result from deficiencies in immune system development and/or function. IEIs can be broadly classified as disorders of adaptive immunity (e.g., combined or humoral immunodeficiencies) or of innate immunity (e.g., phagocyte and complement disorders). Although the clinical manifestations of IEIs are highly variable, traditionally many disorders involve an increased susceptibility to infection. Research in recent years has underscored how IEI can present with features other than infection such as: severe atopy, autoimmunity, autoinflammation, lymphoproliferation, and/or malignancy resulting from immune dysregulation. Early consultation with a clinical immunologist is essential, as timely diagnosis and treatment are imperative for preventing significant disease-associated morbidity and mortality. The treatment of IEIs is complex and generally requires both supportive and definitive strategies, including but not limited to, immunoglobulin replacement therapy, antibiotic prophylaxis, immune response modifiers, and hematopoietic stem cell transplantation. This article provides an overview of the major categories of IEIs and strategies for the appropriate diagnosis and management of these disorders.

Assessing humoral immunity in daily practice: A retrospective study in a pediatric tertiary center

The evaluation of humoral immunity is usually performed through the assessment of serum immunoglobulin levels, vaccine titer responses, and B-cell enumeration and phenotyping. We performed a retrospective study assessing humoral immunity in 469 pediatric patients referred at the Sainte-Justine University Hospital Center. Almost half of the patients had at least one abnormal humoral immunological parameter at their evaluation, with low vaccine response titer to protein antigen being the most frequent. Fifteen patients (3.2 %) had a proven monogenic IEI, and 21 patients (4.5 %) required Ig replacement. Besides the infectious burden, hypoIgG remains the only parameter associated with Ig replacement therapy after the age of 6 years. Low antibody titers against conjugate vaccines had low sensitivity and positive predictive values for starting Ig replacement. Our study highlights the challenge of evaluating the humoral function in the pediatric population with suspected IEI with significant age and sex-dependent variability between parameters.

IgG testing, immunoglobulin replacement therapy, and infection outcomes in patients with CLL or NHL: real-world evidence

ABSTRACT

Patients with chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL) can develop hypogammaglobulinemia, a form of secondary immune deficiency (SID), from the disease and treatments. Patients with hypogammaglobulinemia with recurrent infections may benefit from immunoglobulin replacement therapy (IgRT). This study evaluated patterns of immunoglobulin G (IgG) testing and the effectiveness of IgRT in real-world patients with CLL or NHL. A retrospective, longitudinal study was conducted among adult patients diagnosed with CLL or NHL. Clinical data from the Massachusetts General Brigham Research Patient Data Registry were used. IgG testing, infections, and antimicrobial use were compared before vs 3, 6, and 12 months after IgRT initiation. Generalized estimating equation logistic regression models were used to estimate odds ratios, 95% confidence intervals, and P values. The study population included 17 192 patients (CLL: n = 3960; median age, 68 years; NHL: n = 13 232; median age, 64 years). In the CLL and NHL cohorts, 67% and 51.2% had IgG testing, and 6.5% and 4.7% received IgRT, respectively. After IgRT initiation, the proportion of patients with hypogammaglobulinemia, the odds of infections or severe infections, and associated antimicrobial use, decreased significantly. Increased frequency of IgG testing was associated with a significantly lower likelihood of severe infection. In conclusion, in real-world patients with CLL or NHL, IgRT was associated with significant reductions in hypogammaglobulinemia, infections, severe infections, and associated antimicrobials. Optimizing IgG testing and IgRT are warranted for the comprehensive management of SID in patients with CLL or NHL.

Evaluating patient immunocompetence through antibody response to pneumococcal polysaccharide vaccine using a newly developed 23 serotype multiplexed assay

Assessing T-cell independent antibody response to polysaccharide vaccines is crucial for diagnosing humoral immune deficiencies. However, immunocompetence criteria based on S. pneumoniae vaccination remain unclear. We evaluated IgG antibody vaccine response in healthy individuals to establish interpretive criteria. Pre- and 4-week post-vaccination sera were collected from 79 adults. Antibody concentrations to PNEUMOVAX 23 serotypes were measured using a multiplexed platform. Immunocompetence was determined by fold increase in post-vaccination response, percentage of serotypes achieving 4- or 2-fold antibody ratio, and post-vaccination concentration ≥ 1.3 μg/mL. Immunogenicity varied widely across the 23 serotypes (26.6% to 94.9% for ≥4-fold increase, 51.9% to 98.7% for ≥2-fold increase). Immunocompetence based on historic criteria of ≥4-fold increase in antibody ratio to ≥70% of serotypes was low (72.2%), but increased to 98.7% with criteria of at least a 2-fold increase and/or post-vaccination concentration ≥ 1.3 μg/mL. Current criteria for assessing immunocompetence may be overly stringent and require updating.

Serological responses and clinical outcomes following a three-dose primary COVID-19 vaccine schedule in kidney transplant recipients and people on dialysis

Objectives

Despite vaccination strategies, people with chronic kidney disease, particularly kidney transplant recipients (KTRs), remained at high risk of poor COVID-19 outcomes. We assessed serological responses to the three-dose COVID-19 vaccine schedule in KTRs and people on dialysis, as well as seroresponse predictors and the relationship between responses and breakthrough infection.

Methods

Plasma from 30 KTRs and 17 people receiving dialysis was tested for anti-Spike receptor binding domain (RBD) IgG and neutralising antibodies (NAb) to the ancestral and Omicron BA.2 variant after Doses 2 and 3 of vaccination.

Results

After three doses, KTRs achieved lower anti-Spike RBD IgG levels (P < 0.001) and NAb titres than people receiving dialysis (P = 0.002). Seropositive cross-reactive Omicron neutralisation levels were achieved in 11/27 (40.7%) KTRs and 11/14 (78.6%) dialysis recipients. ChAdOx1/viral-vector vaccine type, higher mycophenolate dose (> 1 g per day) and lower absolute B-cell counts predicted poor serological responses in KTRs. ChAdOx-1 vaccine type and higher monocyte counts were negative predictors in dialysis recipients. Among ancestral NAb seroresponders, higher NAb levels positively correlated with higher Omicron neutralisation (R = 0.9, P < 0.001). More KTRs contracted SARS-CoV-2 infection (14/30; 47%) than dialysis recipients (5/17; 29%) and had more severe disease. Those with breakthrough infections had significantly lower median interdose incremental change in anti-Spike RBD IgG and ancestral NAb titres.

Conclusion

Serological responses to COVID-19 vaccines in KTRs lag behind their dialysis counterparts. KTRs remained at high risk of breakthrough infection after their primary vaccination schedule underlining their need for booster doses, strict infection prevention measures and close surveillance.

Combined deficient response to polysaccharide-based and protein-based vaccines predicts a severe clinical phenotype

OBJECTIVES

Antibody response on polysaccharide- and protein-based vaccines is useful to test B cell functionality. As only few studies have explored the value of studying immune response to both vaccines, we evaluated the clinical value of anti-polysaccharide and anti-protein Luminex-based multiplex assays in context of primary immunodeficiency (PID) diagnosis.

METHODS

A 10-plex Luminex-based assay detecting antibodies to ten pneumococcal polysaccharide (PnPS) serotypes [present in unconjugated Pneumovax, not in 13-valent pneumococcal conjugated vaccine (PCV)] and a 5-plex assay detecting antibodies to five protein antigens (present in DTap/Tdap) were clinically validated in healthy individuals (n=99) and in retrospective (n=399) and prospective (n=108) patient cohorts. Clinical features of individuals with impaired response to PnPS and/or proteins were compared to those with normal response.

RESULTS

Antigen-specific antibody thresholds were determined in healthy individuals. Individuals with impaired anti-PnPS responses and deficient immunoglobulin levels suffered more from autoimmune diseases and had lower B cell levels compared to individuals with impaired anti-PnPS response with normal immunoglobulin levels. Individuals with combined impaired response to PnPS and proteins showed more severe clinical manifestations compared to individuals with isolated impaired response to PnPS or proteins. Eight of the 11 individuals with severely impaired responses to both PnPS and proteins had common variable immunodeficiency. Evaluation of the anti-PnPS response to four serotypes not contained in 20-valent PCV was comparable to evaluation to ten serotypes not contained in 13-valent PCV.

CONCLUSIONS

Multiplexed assessment of anti-PnPS and anti-protein responses combined with immunoglobulin quantification provides useful clinical information to support PID diagnosis.

Nano-biosensor for SARS-CoV-2/COVID-19 detection: methods, mechanism and interface design

The epidemic of coronavirus disease 2019 (COVID-19) was a huge disaster to human society. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which led to COVID-19, has resulted in a large number of deaths. Even though the reverse transcription-polymerase chain reaction (RT-PCR) is the most efficient method for the detection of SARS-CoV-2, the disadvantages (such as long detection time, professional operators, expensive instruments, and laboratory equipment) limit its application. In this review, the different kinds of nano-biosensors based on surface-enhanced Raman scattering (SERS), surface plasmon resonance (SPR), field-effect transistor (FET), fluorescence methods, and electrochemical methods are summarized, starting with a concise description of their sensing mechanism. The different bioprobes (such as ACE2, S protein-antibody, IgG antibody, IgM antibody, and SARS-CoV-2 DNA probes) with different bio-principles are introduced. The key structural components of the biosensors are briefly introduced to give readers an understanding of the principles behind the testing methods. In particular, SARS-CoV-2-related RNA mutation detection and its challenges are also briefly described. We hope that this review will encourage readers with different research backgrounds to design SARS-CoV-2 nano-biosensors with high selectivity and sensitivity.

Inborn Errors of Immunity: A Role for Functional Testing and Flow Cytometry in Aiding Clinical Diagnosis

With the exponential discovery of new inborn errors of immunity (IEI), it is becoming increasingly difficult to differentiate between a number of the more recently defined disorders. This is compounded by the fact that although IEI primarily present with immunodeficiency, the spectrum of disease is broad and often extends to features typical of autoimmunity, autoinflammation, atopic disease, and/or malignancy. Here we use case studies to discuss the laboratory and genetic tests used that ultimately led to the specific diagnoses.

Cellular assays to evaluate B-cell function

Inborn errors of immunity (IEI) that present with recurrent infections are largely due to antibody (Ab) deficiencies. Therefore, assessment of the B-cell and Ab compartment is a major part of immunologic evaluation. Here we provide an overview about cellular assays used to study B-cell function and focus on lymphocyte proliferation assay (LPA), opsonophagocytic assay (OPA), and the Enzyme-linked Immunosorbent Spot Assay (ELISPOT) including clinical applications and limitations of these techniques. LPAs assess ex-vivo cell proliferation in response to various stimuli. Clinically available LPAs utilize peripheral blood mononuclear cells and mostly assess T-cell proliferation with pokeweed mitogen considered the most B-cell specific stimulus. In the research setting, isolating B cells or using more B-cell specific stimuli such as CD40L with IL-4/IL-21 or the TLR9 ligand CpG can more specifically capture the proliferative ability of B cells. OPAs are functional in-vitro killing assays used to evaluate the ability of IgG Ab to induce phagocytosis applied when assessing the potency of vaccine candidates or along with avidity assays to evaluate the quality of secreted IgG. The B-cell ELISPOT assesses Ab production at a cellular level and can characterize the Ab response of particular B-cell subtypes. It can be used in patients on IgG therapy by capturing specific Abs produced by individual B cells, which is not affected by exogenous IgG from plasma donors, and when assessing the vaccine response in patients on immunomodulatory drugs that can affect memory B-cell function. Emerging approaches that are only available in research settings are also briefly introduced.

Management of secondary immunodeficiency in hematological malignancies in the era of modern oncology

Secondary immunodeficiency (SID) in patients with B-cell hematological malignancies is a common condition that presents with recurrent infection. SID is due to both the inherent immune defects due to the malignancy, as well as secondary to cancer therapies, many of which have B-cell depleting properties. The early diagnosis of SID and the optimization of intervention strategies are key to delivering the most effective cancer treatments and reducing infection-related morbidity and mortality. This review discusses current practice, recommendations, and challenges for SID diagnosis, based on the evaluation of clinical history and laboratory assessments, and the effectiveness of specific vaccines and immunoglobulin replacement therapy in reducing the frequency and recurrence of infections in patients with SID, and the healthcare system-associated costs.

Navigating diagnostic options for inborn errors of immunity in children: a case-based illustration

PURPOSE OF REVIEW

In recent years, there has been a dramatic increase in the number of recognized inborn errors of immunity (IEI), many of which present in childhood. This review discusses diagnostic approaches for some of the more common presentations of IEI in childhood.

RECENT FINDINGS

Implementation of newborn screening (NBS) using the T cell receptor excision circle (TREC) assay has led to the timely identification of patients with severe combined immunodeficiency (SCID) as well as both syndromic and nonsyndromic forms of T cell lymphopenia, including DiGeorge syndrome. Improvements in the availability of immunophenotyping assays, genetic testing and advanced diagnostic techniques such as the artificial thymic organoid system can improve diagnostic clarity and impact management plans. Diagnostic improvements in humoral immunodeficiency include development of novel assays to quantify and functionally evaluate polysaccharide vaccine response.

SUMMARY

IEI represent a rapidly growing field, particularly in paediatrics. Use of state-of-the-art diagnostic testing can facilitate rapid identification of IEI, hopefully allowing for initiation of prompt treatment and improved patient outcomes.

Application of vaccine response in the evaluation of patients with suspected B-cell immunodeficiency: Assessment of responses and challenges with interpretation

Diagnostic vaccination is an integral component in the evaluation of patients suspected to have a B cell or humoral deficiency. Evaluation of antibody production in response to both protein- and polysaccharide-based vaccines aids in distinguishing between specific categories of humoral deficiency. Although assessment of pneumococcal polysaccharide responses is widely available and included in diagnostic guidelines, significant variability still exists in the measurement and interpretation of these responses. Interpretation can also be complicated by age, vaccination history and treatment with immunoglobulin replacement therapy. Despite the challenges and limitations of evaluating pneumococcal polysaccharide vaccine responses, it can provide valuable diagnostic and prognostic information to guide therapeutic intervention. Future efforts are needed to further standardize measurement and interpretation of pneumococcal antibody responses to vaccination and to identify and establish other methods and/or vaccines as alternatives to pneumococcal vaccination to address the challenges in certain patient populations.

Specific antibody deficiency: Pearls and pitfalls for diagnosis

OBJECTIVE

Specific antibody deficiency is an immune deficiency defined by the presence of normal quantitative levels of immunoglobulins but impaired antibody responses to polysaccharide antigens in patients presenting with frequent otosinopulmonary infections with pyogenic bacteria. This review summarizes the pitfalls associated with defining exactly what constitutes an "impaired" antibody response to polysaccharide antigens and the importance of documenting actual pyogenic infections before making a diagnosis of an immune deficiency.

DATA SOURCES

PubMed review using the following words: specific antibody deficiency, pneumococcal vaccination, salmonella vaccination, infectious sinusitis Study Selection: This review focused on key studies that have been utilized to define what constitutes a "normal" humoral immune response to pneumococcal and salmonella vaccination in healthy subjects as well as published papers defining current expert opinion.

RESULTS

Published studies demonstrate wide variability in response to pneumococcal vaccination in healthy individuals making it daunting to define what constitutes an abnormal response. These challenges are exacerbated by striking laboratory variability in reporting results.

CONCLUSION

Clinical evaluations in individuals with self-reported recurrent acute sinusitis or lower respiratory infections need to document an infectious etiology with pyogenic bacteria and must rule out an underlying primary airway inflammatory disorder before consideration is made regarding the presence of an immune deficiency. In addition, decision making regarding diagnosis and treatment of patients being evaluated for humoral immunodeficiency should not hinge solely on the strict application of defined cutoffs for "normal" response to a single polysaccharide vaccine, but rather a global assessment of humoral immune function in the context of the clinical presentation.

Paediatric asthma - all that wheezes is not necessarily asthma - current diagnostic and management strategies

PURPOSE OF REVIEW

Asthma is a frequently encountered chronic medical condition encountered in paediatrics, affecting 7% of children under the age of 18 in the United States. Although asthma is one of the more common conditions that is associated with wheezing, there is a broad differential diagnosis to consider. The purpose of this review is to describe other causes of wheezing outside of asthma in a paediatric population and discuss diagnostic and management strategies to consider when evaluating a child or adolescent with wheezing.

RECENT FINDINGS

The characteristics of the wheezing along with other associated signs and symptoms can be helpful in narrowing the differential diagnosis. The age and the past medical history of the patient are also important aspects to consider when determining next steps in the evaluation and management of paediatric wheezing. In addition to considering other causes of wheezing, it is often necessary to assess for the presence of underlying asthma, and recently updated asthma guidelines from the National Heart, Lung and Blood Institute provide a graded review of various recommendations for making the diagnosis and managing asthma in the clinical setting.

SUMMARY

It is important to maintain a broad differential diagnosis when evaluating a paediatric patient with wheezing.

Antigen-Specific CD4+ T-Cell Activation in Primary Antibody Deficiency After BNT162b2 mRNA COVID-19 Vaccination

Previous studies on immune responses following COVID-19 vaccination in patients with common variable immunodeficiency (CVID) were inconclusive with respect to the ability of the patients to produce vaccine-specific IgG antibodies, while patients with milder forms of primary antibody deficiency such as immunoglobulin isotype deficiency or selective antibody deficiency have not been studied at all. In this study we examined antigen-specific activation of CXCR5-positive and CXCR5-negative CD4⁺ memory cells and also isotype-specific and functional antibody responses in patients with CVID as compared to other milder forms of primary antibody deficiency and healthy controls six weeks after the second dose of BNT162b2 vaccine against SARS-CoV-2. Expression of the activation markers CD25 and CD134 was examined by multi-color flow cytometry on CD4⁺ T cell subsets stimulated with SARS-CoV-2 spike peptides, while in parallel IgG and IgA antibodies and surrogate virus neutralization antibodies against SARS-CoV-2 spike protein were measured by ELISA. The results show that in CVID and patients with other milder forms of antibody deficiency normal IgG responses (titers of spike protein-specific IgG three times the detection limit or more) were associated with intact vaccine-specific activation of CXCR5-negative CD4⁺ memory T cells, despite defective activation of circulating T follicular helper cells. In contrast, CVID IgG nonresponders showed defective vaccine-specific and superantigen-induced activation of both CD4⁺T cell subsets. In conclusion, impaired TCR-mediated activation of CXCR5-negative CD4⁺ memory T cells following stimulation with vaccine antigen or superantigen identifies patients with primary antibody deficiency and impaired IgG responses after BNT162b2 vaccination.

A Critical Review on the Standardization and Quality Assessment of Nonfunctional Laboratory Tests Frequently Used to Identify Inborn Errors of Immunity

Inborn errors of immunity (IEI), which were previously termed primary immunodeficiency diseases, represent a large and growing heterogeneous group of diseases that are mostly monogenic. In addition to increased susceptibility to infections, other clinical phenotypes have recently been associated with IEI, such as autoimmune disorders, severe allergies, autoinflammatory disorders, benign lymphoproliferative diseases, and malignant manifestations. The IUIS 2019 classification comprises 430 distinct defects that, although rare individually, represent a group affecting a significant number of patients, with an overall prevalence of 1:1,200-2,000 in the general population. Early IEI diagnosis is critical for appropriate therapy and genetic counseling, however, this process is deeply dependent on accurate laboratory tests. Despite the striking importance of laboratory data for clinical immunologists, several IEI-relevant immunoassays still lack standardization, including standardized protocols, reference materials, and external quality assessment programs. Moreover, well-established reference values mostly remain to be determined, especially for early ages, when the most severe conditions manifest and diagnosis is critical for patient survival. In this article, we intend to approach the issue of standardization and quality control of the nonfunctional diagnostic tests used for IEI, focusing on those frequently utilized in clinical practice. Herein, we will focus on discussing the issues of nonfunctional immunoassays (flow cytometry, enzyme-linked immunosorbent assays, and turbidimetry/nephelometry, among others), as defined by the pure quantification of proteins or cell subsets without cell activation or cell culture-based methods.

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.

Factors associated with IgG levels in adults with IgG subclass deficiency

Background

Factors associated with IgG levels in adults with IgG subclass deficiency (IgGSD) are incompletely understood. We studied adults with IgGSD with subnormal IgG1 only, subnormal IgG1/IgG3, or subnormal IgG3 only without other subnormal IgG subclasses, IgA, or IgM. We compiled: age; sex; autoimmune condition(s) (AC); atopy; IgG, IgG subclasses, IgA, IgM; IgGsum (IgG1 + IgG2 + IgG3 + IgG4); and D (percentage difference between IgGsum and IgG). We compared attributes of patients with/without subnormal IgG (< 7.00 g/L; subnormal IgG1 subclass groups only) and analyzed IgGsum and IgG relationships. We performed backward stepwise regressions on IgG using independent variables IgG subclasses, age, and sex and on D using independent variables age and sex.

Results

There were 39 patients with subnormal IgG1 only (89.7% women), 53 with subnormal IgG1/IgG3 (88.7% women), and 115 with subnormal IgG3 only (91.3% women). Fifteen patients (38.5%) and 32 patients (60.4%) in the respective subnormal IgG1 subclass groups had subnormal IgG. Attributes of patients with/without IgG < 7.00 g/L were similar, except that AC prevalence was lower in patients with subnormal IgG1 only and IgG < 7.00 g/L than ≥ 7.00 g/L (p = 0.0484). Mean/median IgG1 and IgG2 were significantly lower in patients with IgG < 7.00 g/L in both subnormal IgG1 subclass groups (p < 0.0001, all comparisons). Regressions on IgG in three subclass groups revealed positive associations with IgG1 and IgG2 (p < 0.0001 each association). Regressions on D revealed no significant association. IgG1 percentages of IgGsum were lower and IgG2 percentages were higher in patients with subnormal IgG1 subclass levels than subnormal IgG3 only (p < 0.0001 all comparisons).

Conclusions

We conclude that both IgG1 and IgG2 are major determinants of IgG in patients with subnormal IgG1, combined subnormal IgG1/IgG3, or subnormal IgG3 and that in patients with subnormal IgG1 or combined subnormal IgG1/IgG3, median IgG2 levels are significantly lower in those with IgG < 7.00 g/L than those with IgG ≥ 7.00 g/L.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-021-00447-3.

The Heart of the Matter: Secondary Hypogammaglobulinemia and Constrictive Pericarditis

Constrictive pericarditis is the final common result of a number of processes that affect the pericardium. Establishing the diagnosis and determining the underlying etiology of constrictive pericarditis are often a diagnostic rendezvous. Here, we describe a patient who presented to the general practitioner with edema, ascites, and weight gain and was found to have constrictive pericarditis secondary to an inflammatory myofibroblastic tumor of the mediastinum. Interestingly, she had a relative lack of cardiorespiratory complaints, and, aside from the edema and mildly elevated jugular venous pressure, she had an unremarkable cardiac and pulmonary examination. During the diagnostic evaluation for constrictive pericarditis, she was found to have hypogammaglobulinemia and profound lymphocytopenia. A stool α-1-antitrypsin level was sent and was elevated, which confirmed the diagnosis of protein-losing enteropathy, a rare but important complication of constrictive pericarditis. This case highlights important diagnostic considerations and management of these complications for the general practitioner.

Rapid and unamplified identification of COVID-19 with morpholino-modified graphene field-effect transistor nanosensor

SARS-CoV-2 RNA is identified as a pivotal player to bolster energizing zones of COVID-19 detection. Herein, we develop a rapid and unamplified nanosensing platform for detection of SARS-CoV-2 RNA in human throat swab specimens. A gold nanoparticle (AuNP)-decorated graphene field-effect transistor (G-FET) sensor was fabricated, after which complementary phosphorodiamidate morpholino oligos (PMO) probe was immobilized on the AuNP surface. This sensor allowed for highly sensitive testing of SARS-CoV-2 RdRp as PMO does not have charges, leading to low background signal. Not only did the method present a low limit of detection in PBS (0.37 fM), throat swab (2.29 fM), and serum (3.99 fM), but also it achieved a rapid response to COVID-19 patients’ samples within 2 min. The developed nanosensor was capable of analyzing RNA extracts from 30 real clinical samples. The results show that the sensor could differentiate the healthy people from infected people, which are in high agreement with RT-PCR results (Kappa index = 0.92). Furthermore, a well-defined distinction between SARS-CoV-2 RdRp and SARS-CoV RdRp was also made. Therefore, we believe that this work provides a satisfactory, attractive option for COVID-19 diagnosis.

Comparison of management options for specific antibody deficiency

Background: Specific antibody deficiency is a primary immunodeficiency characterized by normal immunoglobulins with an inadequate response to polysaccharide antigen vaccination. This disease can result in recurrent infections, the most common being sinopulmonary infections. Treatment options include clinical observation, prophylactic antibiotic therapy, and immunoglobulin supplementation therapy, each with limited clinical data about their efficacy. Objective: This study aimed to identify whether there was a statistically significant difference in the rate of infections for patients who were managed with clinical observation, prophylactic antibiotics, or immunoglobulin supplementation therapy. Methods: A retrospective chart review was conducted. Patients were eligible for the study if they had normal immunoglobulin levels, an inadequate antibody response to polysaccharide antigen-based vaccination, and no other known causes of immunodeficiency. Results: A total of 26 patients with specific antibody deficiency were identified. Eleven patients were managed with immunoglobulin supplementation, ten with clinical observation, and five with prophylactic antibiotic therapy. The frequency of antibiotic prescriptions was assessed for the first year after intervention. A statistically significant rate of decreased antibiotic prescriptions after intervention was found for patients treated with immunoglobulin supplementation (n = 11; p = 0.0004) and for patients on prophylactic antibiotics (n = 5; p = 0.01). There was no statistical difference in antibiotic prescriptions for those patients treated with immunoglobulin supplementation versus prophylactic antibiotics (p = 0.21). Conclusion: Prophylactic antibiotics seemed to be equally effective as immunoglobin supplementation therapy for the treatment of specific antibody deficiency. Further studies are needed in this area.

Unknown cytomegalovirus serostatus in primary immunodeficiency disorders: A new category of transplant recipients

BACKGROUND

Cytomegalovirus (CMV) serostatus of recipient (R) and donor (D) influences hematopoietic stem cell transplant (HSCT) outcome. However, it is not a reliable indicator of CMV infection in primary immunodeficiency disorder (PIDD) recipients who are unable to make adequate antigen-specific immunoglobulin (Ig) or who receive intravenous Ig (IVIg) prior to testing.

OBJECTIVE

Since no data exist on PIDD with unknown CMV serostatus, we aimed to evaluate the relationship between pre-HSCT recipient and donor serostatus and incidence of CMV infection in recipients with unknown serostatus.

METHODS

A retrospective analysis of all pediatric PIDD HSCTs (2007-2018) was performed at University of California San Francisco. Recipients were separated into categories based on pre-transplant serostatus: 1) seropositive (R(+)), 2) seronegative (R(-)), and 3) unknown serostatus (R(x)). Patients with pre-HSCT active CMV viremia were excluded.

RESULTS

A total of 90 patients were included, 69% male. The overall incidence of CMV infection was 20%, but varied in R(+), R(-), and R(x) at 80%, 0%, and 14%, (P-value = .0001). Similarly, 5-year survival differed among groups, 60% R(+), 100% R(-), and 90% of R(x) (P-value = .0045). There was no difference in CMV reactivation by donor serostatus (P-value = .29), however, faster time to clearance of CMV was observed for R(x)/D(+) group (median 9.5 days (IQR 2.5-18), P-value = .024).

CONCLUSION

We identify a novel group of recipients, R(x), with an intermediate level of survival and CMV incidence post-HSCT, when compared to seropositive and seronegative recipients. No evidence of CMV transmission from D(+) in R(-) and R(x) was observed. We believe R(x) should be considered as a separate category in future studies to better delineate recipient risk status.