Specific Antibody Deficiency: Controversies in Diagnosis and Management

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.

Exploring the Significance of Immune Checkpoints and EBV Reactivation in Antibody Deficiencies with Near-Normal Immunoglobulin Levels or Hyperimmunoglobulinemia

This study delves into the intricate landscape of primary immunodeficiencies, with a particular focus on antibody deficiencies characterized by near-normal immunoglobulin levels or hyperimmunoglobulinemia. Contrary to the conventional focus on genetic dysregulation, these studies investigate the key roles of immune checkpoints, such as PD-1/PD-L1, CTLA-4/CD86, and CD200R/CD200, on selected subpopulations of T and B lymphocytes and their serum concentrations of soluble forms in patients recruited for the studies in healthy volunteers. In addition, the studies also show the role of Epstein-Barr virus (EBV) reactivation and interactions with tested pathways of immune checkpoints involved in the immunopathogenesis of this disease. By examining the context of antibody deficiencies, this study sheds light on the nuanced interplay of factors beyond genetics, particularly the immune dysregulations that occur in the course of this type of disease and the potential role of EBV reactivation, which affects the clinical presentation of patients and may contribute to the development of cancer in the future, especially related to hematological malignancies.

Inborn Errors of Immunity in Children With Invasive Pneumococcal Disease: A Multicenter Prospective Study

BACKGROUND

In settings with universal conjugate pneumococcal vaccination, invasive pneumococcal disease (IPD) can be a marker of an underlying inborn error of immunity. The aim of this study was to determine the prevalence and characterize the types of immunodeficiencies in children presenting with IPD.

METHODS

Multicenter prospective audit following the introduction of routinely recommended immunological screening in children presenting with IPD. The minimum immunological evaluation comprised a full blood examination and film, serum immunoglobulins (IgG, IgA and IgM), complement levels and function. Included participants were children in whom Streptococcus pneumoniae was isolated from a normally sterile site (cerebrospinal fluid, pleura, peritoneum and synovium). If isolated from blood, features of sepsis needed to be present. Children with predisposing factors for IPD (nephrotic syndrome, anatomical defect or malignancy) were excluded.

RESULTS

Overall, there were 379 episodes of IPD of which 313 (83%) were eligible for inclusion and 143/313 (46%) had an immunologic evaluation. Of these, 17/143 (12%) were diagnosed with a clinically significant abnormality: hypogammaglobulinemia (n = 4), IgA deficiency (n = 3), common variable immunodeficiency (n = 2), asplenia (n = 2), specific antibody deficiency (n = 2), incontinentia pigmenti with immunologic dysfunction (n = 1), alternative complement deficiency (n = 1), complement factor H deficiency (n = 1) and congenital disorder of glycosylation (n = 1). The number needed to investigate to identify 1 child presenting with IPD with an immunologic abnormality was 7 for children under 2 years and 9 for those 2 years old and over.

CONCLUSIONS

This study supports the routine immune evaluation of children presenting with IPD of any age, with consideration of referral to a pediatric immunologist.

Immunoglobulin repertoire restriction characterizes the serological responses of patients with predominantly antibody deficiency

BACKGROUND

Predominantly antibody deficiency (PAD) is the most common category of inborn errors of immunity and is underpinned by impaired generation of appropriate antibody diversity and quantity. In the clinic, responses are interrogated by assessment of vaccination responses, which is central to many PAD diagnoses. However, the composition of the generated antibody repertoire is concealed from traditional quantitative measures of serological responses. Leveraging modern mass spectrometry-based proteomics (MS-proteomics), it is possible to elaborate the molecular features of specific antibody repertoires, which may address current limitations of diagnostic vaccinology.

OBJECTIVES

We sought to evaluate serum antibody responses in patients with PAD following vaccination with a neo-antigen (severe acute respiratory syndrome coronavirus-2 vaccination) using MS-proteomics.

METHODS

Following severe acute respiratory syndrome coronavirus-2 vaccination, serological responses in individuals with PAD and healthy controls (HCs) were assessed by anti-S1 subunit ELISA and neutralization assays. Purified anti-S1 subunit IgG and IgM was profiled by MS-proteomics for IGHV subfamily usage and somatic hypermutation analysis.

RESULTS

Twelve patients with PAD who were vaccine-responsive were recruited with 11 matched vaccinated HCs. Neutralization and end point anti-S1 titers were lower in PAD. All subjects with PAD demonstrated restricted anti-S1 IgG antibody repertoires, with usage of <5 IGHV subfamilies (median: 3; range 2-4), compared to ≥5 for the 11 HC subjects (P < .001). IGHV3-7 utilization was far less common in patients with PAD than in HCs (2 of 12 vs 10 of 11; P = .001). Amino acid substitutions due to somatic hypermutation per subfamily did not differ between groups. Anti-S1 IgM was present in 64% and 50% of HC and PAD cohorts, respectively, and did not differ significantly between HCs and patients with PAD.

CONCLUSIONS

This study demonstrates the breadth of anti-S1 antibodies elicited by vaccination at the proteome level and identifies stereotypical restriction of IGHV utilization in the IgG repertoire in patients with PAD compared with HC subjects. Despite uniformly pauci-clonal antibody repertoires some patients with PAD generated potent serological responses, highlighting a possible limitation of traditional serological techniques. These findings suggest that IgG repertoire restriction is a key feature of antibody repertoires in PAD.

Ciliary and immune dysfunctions and their genetic background in patients with non-cystic fibrosis bronchiectasis in Central Iran

OBJECTIVE

Bronchiectasis is usually caused by recurrent bacterial infections and is characterized by irreversible dilation of the bronchi. In this study, we aimed to give an overview of the genetic backgrounds of patients with non-cystic fibrosis bronchiectasis (NCFB) that have been suspected to an underlying ciliary dysfunction or inborn error of immunity (IEI).

METHOD

This is a retrospective cross-sectional study. Seventy-one NCFB patients who were referred to the Immunodeficiency Research Center, Isfahan University of Medical Sciences, Isfahan, Iran, from 1996 to 2020 were included. These patients were referred to this center for immunological and genetic evaluation. Genetic analysis with whole-exome sequencing and Sanger sequencing was confirmed in 30 patients. However, the genetic evaluations of 41 patients were either still under evaluation or the patients had refused to be genetically evaluated.

RESULT

Thirty-eight of our 71 patients (53.52%) were diagnosed with ciliary dysfunction and the detected mutations included mutations in the CCDC65, DNAH11, RSPH1, CCDC40, and GAS8 genes as well as a novel mutation. Thirty-three patients (46.47%) had an IEI and the detected mutations included mutations of the following genes: TNFRSF13B, PTPN2, ZNF341 BTK, TCF3, CD79a, PIK3CD, JAGN1, WAS, RFXANK, STK4, GSDMD, and NEMO.

CONCLUSION

This study presents an overview of the underlying ciliary and immune dysfunctions and their genetic mutations in NCFB in a highly consanguine population. This would give us a better understanding of the etiologies and the known and novel genetic mutations in NCFB in Iran and, in turn, in the Middle East and North Africa (MENA) region.

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.

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.

Systemic IgG exposure and safety in patients with primary immunodeficiency: a randomized crossover study comparing a novel investigational wearable infusor versus the Crono pump

Aim: A novel, Investigational Wearable Infusor (IWI) was evaluated in a randomized, controlled, crossover, open-label study to determine if its delivery of subcutaneous immunoglobulin (IgPro20) achieved a comparable area under the concentration-time curve (AUC) for immunoglobulin G (IgG) versus the Crono S-PID-50 infusion pump (CP). EudraCT: 2016-003798-16. Materials & methods: Patients with primary immunodeficiency (PID) were randomized to receive IgPro20 in Sequence 1 (CP/IWI) or 2 (IWI/CP). The primary end point was AUC for IgG during the final week of each 4-week period. Results: 23 patients were enrolled. Evaluation of area under the concentration-time curve from time 0 (pre-infusion) to 7 days after infusion (AUC_0-7 days) (IWI: 1806 h*g/l; CP: 1829 h*g/l) and geometric mean ratio indicated comparable AUCs for IgG for both devices. Conclusion: Similar IgG exposure, indicated by AUC values, can be achieved with IgPro20 using the IWI or CP in PID.

Immunoglobulin treatment for B-cell immunodeficiencies

This article aims to describe the rationale and utility of immunoglobulin therapies in patients with B-cell immunodeficiency states. We describe the historical perspective, mechanism of actions, and indications for use in this population. We then focus upon management pearls and special considerations for its utility. Finally, we elaborate upon the important economic implications for these patients and the need to develop individualized management strategies in this vulnerable population.

A low level of naturally occurring antibodies associates with functional antibody deficiency

Functional antibody deficiency is clinically assessed from antibody responses to vaccination. However, diagnostic vaccination is complex and may fail in practice. We hypothesized that the levels of naturally occurring antibodies against galactose-α-1,3-galactose (αGal) may represent alternative markers of functional antibody capacity. We included data from 229 patients with suspected primary immunodeficiency in a retrospective study. Antibody levels against αGal and twelve pneumococcal serotypes were determined with solid-phase immunoassays. Pneumococcal vaccinations and treatment with normal human immunoglobulin were assessed from medical records. Anti-αGal antibody levels correlated positively with anti-pneumococcal antibody levels measured before and after pneumococcal vaccination. Contrary to the anti-pneumococcal antibody levels, the anti-αGal antibody level showed potential for predicting subsequent immunoglobulin treatment - a marker of disease severity. Naturally occurring antibodies may reflect the functional capacity tested by diagnostic vaccination but add more useful clinical data. The clinical utility of this easy test should be evaluated in prospective studies.

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.

One-year intravenous immunoglobulin replacement therapy: efficacy in reducing hospital admissions in pediatric patients with Inborn Errors of Immunity

OBJECTIVES

To compare the frequency of hospitalization in children with Inborn Errors of Immunity with antibody deficiency previous to intravenous immunoglobulin (pre- IVIG) with a one-year period after initial IVIG (post-IVIG).

METHODS

Medical reports of 45 patients during an eight-year period were reviewed from 2018 to 2019. Wilcoxon-test was used for related samples.

RESULTS

Forty-five children were included in the study, aged 29-249 months of age, and most of them (64.4%) were males. Median ages at onset symptoms and at diagnosis were 6 and 73 months old, respectively. Specific antibody deficiency and unclassified hypogammaglobulinemia were the predominant diagnoses (31.1% and 17.8%, respectively). X-linked agammaglobulinemia, Hyper IgE syndrome, Hyper IgM, transient hypogammaglobulinemia of infancy, and Common Variable Immunodeficiency (CVID) were also reported, in a low frequency. Forty-four (97.8%) patients were hospitalized before IVIG, and 10 patients (22.2%) after. Annual mean hospital admission reduced from 2.5 to 0.5, pre and post-IVIG, respectively (p < 0.0001). Mean length of stay (LOS) reduced from 71 to 4.7 days/year (p < 0.0001) in general ward and in the PICU from 17.2 days/year to zero (p < 0.0002). Pneumonia was the main cause of hospital admission with a reduction in the number of episodes per patient from an average of 2.2-0.1 per year (p < 0.001). Concomitant use of antibiotic prophylaxis did not influence the number of hospital admission.

CONCLUSION

One-year intravenous IVIG significantly decreased the number of hospitalizations and length of stay in children with impaired antibody production. Social and economic impacts would be required.

Evaluation of Specific Antibody Responses in Patients with Selective IgA Deficiency and Ataxia Telangiectasia

BACKGROUND

Specific Antibody Deficiency (SAD) is a primary immunodeficiency disease (PID) characterized by the occurrence of recurrent infections and inadequate antibody response to polysaccharide new antigens.

OBJECTIVE

This study aims to determine the titer of specific antibodies against unconjugated 23-valent pneumococcal polysaccharide vaccine (PPSV-23), the presence of SAD, and its association with clinical and laboratory findings in Ataxia-telangiectasia (A-T) and selective immunoglobulin A deficiency (SIgAD) patients.

METHODS

32 A-T patients and 43 SIgAD patients were included in the study. Samples of the patients were obtained before and three weeks after vaccination with PPSV-23. Specific immunoglobulin G (IgG) directed towards pneumococcal capsular antigen and specific antibodies against whole pneumococcal antigens was measured.

RESULTS

Comparison of the response to vaccination revealed that 81.3% of A-T patients and 18.6% of the SIgAD patients had an inadequate response to PPSV-23 (p<0.001). The prevalence of recurrent infection (p=0.034) and pneumonia (p=0.003) in SIgAD patients was significantly higher in non-responders than responders. Likewise, the number of marginal zone B cells (p=0.037), transitional B cells (p=0.019), plasmablasts (p=0.019), CD8+ naïve T cells (p=0.036), and percentage of CD8+ T cells (p=0.047), switched memory B cells (SMB) (p=0.026) and immunoglobulin M (IgM) memory B cells (p=0.022) in SIgAD patients were significantly lower in non-responder group than responder group. In contrast, the percentage of CD4 T+ cells in A-T patients was lower in the non-responder group than responders (p=0.035).

CONCLUSION

SAD is more frequent in A-T patients than SIgAD patients. The role of SMB and T cells should not be underestimated in SAD.

Healthcare utilization for sinusitis after pneumococcal vaccination in patients with low antibody titers

BACKGROUND

Pneumococcal antibody deficiency has been the subject of limited study in chronic rhinosinusitis (CRS) and has not been studied in recurrent acute rhinosinusitis (RARS). The 23-valent pneumococcal polysaccharide vaccine (PPSV23) is considered for patients with non-protective Streptococcus pneumoniae titers. We hypothesized that both RARS and CRS patients with deficient S. pneumoniae titers and subsequent PPSV23 vaccination would have reduced healthcare encounters for sinusitis and fewer prescriptions for antibiotics or steroids.

METHODS

A retrospective cohort study was performed of patient encounters between January 2011 and December 2019. All patients included were ≥18 and ≤65 years old with a diagnosis of CRS or RARS and pneumococcal titer data. Patients with immunodeficiency and comorbid conditions requiring PPSV23 vaccination prior to the age of 65 were excluded.

RESULTS

A total of 938 patients were included. Non-protective antibody titers were present in 75.8% of CRS and 74.8% of RARS patients. 306 patients with deficient antibody titers received the PPSV23 vaccine. 89% of CRS and 90.1% of RARS patients had protective responses. Among 217 patients with continuous data from 2 years before through 2 years after PPSV23 vaccination, a decrease in the number of encounter diagnoses of CRS (p<0.0001) and RARS (p = 0.0006) was observed. Decreases in the frequency of antibiotic (p = 0.002) and corticosteroid (p = 0.04) prescriptions were also appreciated.

CONCLUSIONS

Most patients with CRS and RARS have non-protective antibody titers. PPSV23 administration significantly decreases healthcare utilization. This article is protected by copyright. All rights reserved.

Diagnostic Vaccination in Clinical Practice

Testing the antibody response to vaccination (diagnostic vaccination) is crucial in the clinical evaluation of primary immunodeficiency diseases. Guidelines from the American Academy of Allergy, Asthma & Immunology (AAAAI) provide detailed recommendations for diagnostic vaccination with pure pneumococcal polysaccharide vaccines (PPV). However, the degree of compliance with these guidelines and the utility of the guidelines in actual practice are undescribed. To address this, we systematically evaluated diagnostic vaccination in adult patients with suspected primary immunodeficiency diseases in a single tertiary center from 2011 to 2016 (n = 229). We found that full compliance with the AAAAI guidelines was achieved for only 39 patients (17%), suggesting that the guidelines are not easy to follow. Worse, interpretation according to the guidelines was heavily influenced by which serotype-specific antibodies that were used for the evaluation. We found that the arbitrary choices of serotype-specific antibodies could change the fraction of patients deemed to have ‘adequate immunity’ by a factor of four, exposing an inherent flaw in the guidelines. The flaw relates to dichotomous principles for data interpretation under the AAAAI guidelines. We therefore propose a revised protocol for diagnostic vaccination limited to PPV vaccination, subsequent antibody measurements, and data interpretation using Z-scores. The Z-score compiles multiple individual antibody levels, adjusted for different weighting, into one single continuous variable for each patient. In contrast to interpretation according to the AAAAI guidelines, the Z-scores were robust to variations in the choice of serotype-specific antibodies used for interpretation. Moreover, Z-scores revealed reduced immunity after vaccination in the patients with recurrent pneumonia (a typical symptom of antibody deficiency) compared with control patients. Assessment according to the AAAAI guidelines failed to detect this difference. We conclude that our simplified protocol and interpretation with Z-scores provides more robust clinical results and may enhance the value of diagnostic vaccination.

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.

Intravenous immunoglobulin and the current risk of moderate and severe anaphylactic events, a cohort study

This large cohort study from the US Premier Healthcare Database evaluated the risk and predictors of anaphylaxis in association with intravenous immunoglobulin (IvIg) therapy in the inpatient and outpatient setting. Data were collected retrospectively (January 2009-December 2018) from 24 919 patients administered IgPro10 IvIg, median age 54 years. Immunoglobulins of interest were IgPro10 and other IvIg given before or after IgPro10. Moderate and severe anaphylaxis was identified from same-day parenteral epinephrine and IvIg use and reviews of patient record summaries. Predictors for first anaphylactic reactions associated with IvIg administration were derived from adjusted incidence rate ratios (IRR) using Poisson regression. Moderate anaphylaxis in IvIg use was rare and severe anaphylaxis very rare based on a total of 124 moderate and four non-fatal severe first anaphylactic events, incidence rate of 7.11 and 0.23/10 000 IvIg administrations, respectively. Age under 18 years was an independent predictor of moderate or severe anaphylactic events [adjusted incidence rate ratio = 2.94, 0.95 confidence interval  = 1.91-4.52] compared with those aged 18 years and older. First IvIg administration was a strong predictor of anaphylaxis. The IRR in those with a subsequent IvIg administration in the preceding 42 days decreased to 0.27 (0.17-0.42) and in those effectively IvIg-naive (no IvIg for > 42 days) to 0.76 (0.44-1.32) compared with first IvIg use. The key conclusions from this study are that the risk of anaphylaxis has progressively reduced over the last decade, from 14.87 of 10 000 in 2009-10 to 4.39 of 10 000 IvIg administrations in 2017-18 and is rare overall, and that the risk of anaphylaxis is increased in those aged under 18 years.

Robust Antibody and T Cell Responses to SARS-CoV-2 in Patients with Antibody Deficiency

Immunocompromised patients, including those with inborn errors of immunity (IEI), may be at increased risk for severe or prolonged infections with SARS-CoV-2 (Zhu et al. N Engl J Med. 382:727-33, 2020; Guan et al. 2020; Minotti et al. J Infect. 81:e61-6, 2020). While antibody and T cell responses to SARS-CoV-2 structural proteins are well described in healthy convalescent donors, adaptive humoral and cellular immunity has not yet been characterized in patients with antibody deficiency (Grifoni et al. Cell. 181:1489-1501 e1415, 2020; Burbelo et al. 2020; Long et al. Nat Med. 26:845-8, 2020; Braun et al. 2020). Herein, we describe the clinical course, antibody, and T cell responses to SARS-CoV-2 structural proteins in a cohort of adult and pediatric patients with antibody deficiencies (n = 5) and controls (related and unrelated) infected with SARS-CoV-2. Five patients within the same family (3 with antibody deficiency, 2 immunocompetent controls) showed antibody responses to nucleocapsid and spike proteins, as well as SARS-CoV-2 specific T cell immunity at days 65-84 from onset of symptoms. No significant difference was identified between immunocompromised patients and controls. Two additional unrelated, adult patients with common variable immune deficiency were assessed. One did not show antibody response, but both demonstrated SARS-CoV-2-specific T cell immunity when evaluated 33 and 76 days, respectively, following SARS-CoV-2 diagnosis. This report is the first to show robust T cell activity and humoral immunity against SARS-CoV-2 structural proteins in some patients with antibody deficiency. Given the reliance on spike protein in most candidate vaccines (Folegatti et al. Lancet. 396:467-78, 2020; Jackson et al. N Engl J Med. 383:1920-31, 2020), the responses are encouraging. Additional studies will be needed to further define the timing of onset of immunity, longevity of the immune response, and variability of response in immunocompromised patients.

Inborn Errors of Immunity: how to diagnose them?

OBJECTIVES

Inborn Errors of Immunity are characterized by infectious conditions and manifestations of immune dysregulation. The diversity of clinical phenotypes can make it difficult to direct the laboratory investigation. This article aims to update the investigation of immunological competence in the context of primary defects of the immune system.

SOURCE OF DATA

Searches were carried out on Pubmed to review articles published in the last five years, in English, French or Spanish, using the terms "diagnosis" OR "investigation" AND "immunodeficiency" or "primary immunodeficiency" or "inborn errors of immunity" NOT "HIV". Recent textbook editions have also been consulted.

SUMMARY OF FINDINGS

The immune system competence investigation should be started based on clinical phenotypes. Relevant data are: characterization of infectious conditions (location, recurrence, types of infectious agents, response to treatment), age during symptom onset and associated manifestations (growth impairment, allergy, autoimmunity, malignancies, fever and signs of inflammation without the identification of infection or autoimmunity) and family history. These data contribute to the selection of tests to be performed.

CONCLUSIONS

The diagnostic investigation of Inborn Errors of Immunity should be guided by the clinical characterization of patients, aiming to optimize the use of complementary tests. Many diagnoses are attained only through genetic tests, which are not always available. However, the absence of a diagnosis of certainty should never delay the implementation of therapeutic measures that preserve patient life and health.

Bronchiectasis severity correlates with outcome in patients with primary antibody deficiency

Bronchiectasis is a well-recognised complication of primary antibody deficiency (PAD) syndromes. Previous data suggest that mortality in common variable immune deficiency (CVID) is not associated with isolated bronchiectasis. A retrospective analysis of patients with CVID and specific antibody deficiency in two tertiary referral centres with lung disease was conducted. Severity of bronchiectasis at presentation was associated with mortality. Lower FEV₁, colonisation with Pseudomonas aeruginosa and a diagnosis of COPD were also associated with mortality. Bronchiectasis is an important driver of mortality in patients with PAD syndromes.

Treating secondary antibody deficiency in patients with haematological malignancy: European expert consensus

OBJECTIVES

Secondary antibody deficiency (SAD), associated with severe, recurrent or persistent infections, is common in patients with haematological malignancies (HM), but unifying guidance on immunoglobulin replacement therapy (IgRT) in these patients is lacking. We aimed to develop consensus statements for the use of IgRT in patients with HM.

METHODS

A Delphi exercise was employed to test the level of agreement on statements developed by a Task Force based on available data and their clinical experience. In Round 1, an Expert Panel, comprising specialist EU physicians caring for patients with HM, helped to refine the statements. In Round 2, experts rated their agreement with the statements. In Round 3, experts who had scored their agreement as ≤4 were invited to review their agreement based on the overall feedback.

RESULTS

Three definitions and 20 statements were formulated and tested for consensus, covering measurement of IgG levels, initiation and discontinuation of IgRT, dosing, and the use of subcutaneous IgG. Consensus (agreement ≥70% on Likert-type scale) was reached for all three definitions and 18 statements.

CONCLUSIONS

Recommendations have been developed with the aim of providing guidance for the use of IgRT to prevent severe, recurrent or persistent infections in patients with HM and SAD.

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

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

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.

Comparison of Two Different Criteria for Specific Antibody Deficiency in Patients With Chronic and Recurrent Rhinosinusitis

Background

Specific antibody deficiency (SAD) is highly associated with chronic rhinosinusitis (CRS) and is defined by inadequate post-vaccination percentage of protective (≥1.3 ug/mL) pneumococcal antibody serotypes divided by total tested serotypes (post-pPA).

Objective

Although  < 70% post-pPA has been used commonly as the criterion for SAD, we sought to evaluate the clinical outcome of a different definition of SAD.

Methods

203 patients aged 6 to 70 years with CRS were classified, retrospectively by pre-vaccination pPA (pre-pPA) and post-pPA by two different criteria. Using 70% as the threshold for adequate pneumococcal antibody (PA) response, patients were classified as: Group A (adequate pre-pPA), Group B (inadequate pre-pPA, adequate post-pPA), Group C (inadequate pre-pPA, inadequate post-pPA, SAD). Using 50% as the threshold, patients were similarly classified as: Group A’, B’ and C’.

Results

The recurrence rate of sinusitis during the next one year in Group A (pre-pPA ≥70%) was significantly less than that of Group A’ (pre-pPA ≥50%) (10% vs. 34%, P = .03). Group A had lower incidence of sinusitis than Group B (pre-pPA < 70%, post-pPA ≥70%) (10% vs. 34%, P = .025). Among Group B’ patients, the recurrence rate of sinusitis was significantly less among those with post-pPA of ≥70% than those with 50%–69% (28% vs. 69%, P < .01).

Conclusion

Employment of a 70% pPA threshold for SAD in comparison to a 50% threshold would decrease the incidence of sinusitis in the next one year by vaccinating patients in 51–69% pPA range. Pre-existing PAs (Group A) yielded a higher protection against sinusitis than vaccine-acquired antibodies (Group B).

Infection Phenotypes Among Patients with Primary Antibody Deficiency Mined from a US Patient Registry

PURPOSE

Primary immunodeficiency disorders (PIDs) affect immune system development and/or function, increase infection susceptibility, and cause dysregulation or both. Recognition of PID requires assessment about the normal state of infection frequency and microbiology. To help clarify infection characteristics, we use data mined from the US Immunodeficiency Network (USIDNET) registry among primary antibody deficiency (PAD) patients before diagnosis.

METHODS

We analyzed PAD patient data from the USIDNET registry prior to ultimate diagnosis. Our analysis included basic descriptive statistics for 8 major infection subtypes and significance testing for comparing infection rate by specific organisms across 7 distinct PAD subtypes.

RESULTS

Of 2038 patients reviewed, 1259 (61.8%) had infections reported prior to diagnosis. Most (77.4%) had four or less reported infections prior to diagnosis; however, some suffered up to 16 infections. Infection patterns differed across the PAD subtypes. Patients with agammaglobulinemia differed significantly from patients with all other forms of PAD studied in at least one infection category, whereas patients with CVID differed from 3 other PAD categories in at least one infection category. Patterns of infections in patients with hypogammaglobulinemia, specific antibody deficiency, and transient hypogammaglobulinemia were less unique. For each of the infection types, bacteria were the most prevalent cause of disease.

CONCLUSIONS

Our data shows that distinct subtypes of PAD display unique infection patterns. We also show that patients with agammaglobulinemia suffer more invasive infections and differ most significantly from all other forms of PAD studied. Our analysis has broad implications about infection surveillance, progression, and vulnerability by PAD subtype.

Isolating polysaccharide IgG pneumococcal antibody responses by pre-adsorption of conjugate vaccine serotypes: A modified approach for the conjugate vaccine era

BACKGROUND

Assessment of pure polysaccharide response to the 23-valent pneumococcal polysaccharide vaccine (PPV23) can be biased by previous exposure to the conjugate vaccine (PCV). We applied pre-analytical modification to the existing ELISA by pre-incubating serum with PCV.

METHODS

PCV-adsorbed and non-adsorbed sera were prepared before measuring the concentration of anti-pneumococcal capsular polysaccharide (PCP) IgG antibodies by the whole pneumococcal ELISA. Paired pre and post-pneumococcal vaccination sera from 73 subjects were analyzed and the baseline anti-PCP IgG for each sample was subtracted from the post-vaccination value to measure vaccine responses. Absolute change in titers and fold changes were then compared between both methods.

RESULTS

In the PCV-vaccinated group (n = 28), pre-adsorption with PCV significantly reduced the vaccine responses compared to non-adsorbed sera [median increase in anti-PCP titers: 27.55 mg/l and 45.98 mg/l, respectively]. In addition, the median fold change dropped significantly from 3.026 to 2.313. In PPV23-vaccinated immunocompetent subjects (n = 28) there was a significant difference in anti-PCP responses with PCV adsorption [median values: 73.71 mg/l without and 51.04 mg/l with adsorption]. All the antibody deficiency patients (n = 17) displayed poor PPV23 responses. Although PPV23 responsiveness was not statistically different between both methods, we have observed a trend for lower anti-PCP IgG titers in PCV-adsorbed sera compared to non-adsorbed ones. Serotype-specific IgG analysis using a multiplexed bead-based immunoassay performed on 10 paired samples confirmed that the adsorption observed is specific to PCV serotypes.

CONCLUSION

Pre-analytical modification to the conventional ELISA by removing the PCV-specific serotypes may differentiate true polysaccharide response from recall response induced by previous PCV vaccination.

B Cell Disorders in Children: Part II

PURPOSE OF REVIEW

B cell disorders result in decreased levels or function of immunoglobulins in an individual. Genetic mutations have been reported in a variety of B cell disorders. This review, in follow-up to a previous review, describes some rare B cell disorders as well as their known underlying genetic etiologies.

RECENT FINDINGS

Genetic studies identify and permit precise classification of an increasing number of B cell disorders, leading to a greater understanding of B cell development and function. The B cell disorders are rare diseases. While clinicians are most familiar with X-linked agammaglobulinemia and so-called common variable immunodeficiency (CVID), there are many causes of hypogammaglobulinemia. Genetic testing provides a specific diagnosis, offers useful information for genetic counseling, and can identify previously unrecognized B cell disorders.

Diagnosis and management of Specific Antibody Deficiency

Specific antibody deficiency is a primary immunodeficiency disease recognized by the International Union of Immunology Societies and defined by recurrent respiratory infections with normal immunoglobulins, but diminished antibody responses to polysaccharide antigens after vaccination with the 23 valent pneumococcal polysaccharide vaccine. Clinical immunologists struggle with diagnosis and treatment, because the definition of an adequate response to immunization remains controversial. Specific antibody deficiency is managed clinically with close follow-up and prompt treatment of infections, antibiotic prophylaxis, or immune globulin therapy. Treatment is individualized using clinical judgment and existing practice guidelines, which will likely evolve as more studies become available.

The architecture of the IgG anti-carbohydrate repertoire in primary antibody deficiencies

Immune system failure in primary antibody deficiencies (PADs) has been linked to recurrent infections, autoimmunity, and cancer, yet clinical judgment is often based on the reactivity to a restricted panel of antigens. Previously, we demonstrated that the human repertoire of carbohydrate-specific immunoglobulin G (IgG) exhibits modular organization related to glycan epitope structure. The current study compares the glycan-specific IgG repertoires between different PAD entities. Distinct repertoire profiles with extensive qualitative glycan-recognition defects were observed, which are characterized by the common loss of Galα and GalNAc reactivity and disease-specific recognition of microbial antigens, self-antigens, and tumor-associated carbohydrate antigens. Antibody repertoire analysis may provide a useful tool to elucidate the degree and the clinical implications of immune system failure in individual patients.

Pneumococcal vaccination in lung transplant patients

Introduction: This review analyzes the efficacy of pneumococcal vaccinations in lung transplant patients before and after transplantation.Areas covered: This review addresses the risk for respiratory infections, in particular pneumococcal infections, in lung transplantation patients in the context of immunodeficiency and immunosuppressive medication. Vaccination is recommended to counteract the increased risk of pneumococcal infection, and the relevant guidelines are discussed in this review. The design of specific vaccination schedules is required because of the impaired antibody response in specific patient categories.Expert opinion: Lung transplantation candidates should be vaccinated with pneumococcal vaccines prior to transplantation. Currently, the 23-valent pneumococcal polysaccharide vaccine offers the broadest coverage, but the antibody response should be monitored. New generation pneumococcal conjugate vaccines with equally broad serotype coverage could be used in the future. During the post-transplantation period, the immune status of the patients should be monitored regularly, and vaccination should be repeated when indicated.

Low Baseline Pneumococcal Antibody Titers Predict Specific Antibody Deficiency, Increased Upper Respiratory Infections, and Allergy Sensitization

Background

Inadequate titers of pneumococcal antibody (PA) are commonly present among patients with recurrent respiratory infections.

Objective

We sought to determine the effect of the degree of inadequacy in baseline PA titers on the subsequent polysaccharide vaccine response, the incidence of sinusitis, and allergic conditions.

Methods

A total of 313 patients aged 6 to 70 years with symptoms of recurrent respiratory infections were classified by baseline-pPA (percentage of protective [≥1.3 µg/mL] PA serotypes/total tested serotypes) and postvaccination pPA (post-pPA): Group A (adequate baseline-pPA), Group B (inadequate baseline-pPA, adequate post-pPA, responders), and Group C (inadequate baseline-pPA, inadequate postpPA, nonresponders, specific antibody deficiency [SAD]). Immunity against Streptococcus pneumoniae was defined as adequate when the pPA was ≥70%. Each group and combined groups, Group AB (inadequate baseline-pPA), and Group BC (adequate post-pPA) were analyzed for demographics, history of sinusitis, recurrent sinusitis in the following year, allergic conditions, and association with inadequate individual serotype titers.

Results

Over 80% of patients with respiratory symptoms had inadequate baseline-pPA. Baseline-pPA and SAD prevalence are inversely related (odds ratio = 2.02, 95% CI: 1.15–3.57, P = .01). Inadequate serotype 3 antibody titer is highly associated with SAD (odds ratio = 2.02, 96% CI: 1.61–5.45, P < .01). The groups with inadequate pPA (Group B and C, or BC) had significantly higher percentage of patients with chronic rhinosinusitis (P < .001), allergic sensitization, and allergic rhinitis (P < .05). Group A contained higher percentage of patients with recurrent upper airway infections (P < .001).

Conclusion

Low baseline-pPA and low antibody titers to serotype 3 are highly associated with SAD, increased incidence of respiratory infections including CRS and allergic conditions.

Specific Antibody Immunodeficiency Presenting With Streptococcal pneumonia-Induced Spontaneous Bacterial Peritonitis

Specific antibody immunodeficiency (SAD) is a primary immunodeficiency disorder characterized by normal levels of serum immunoglobulins (IgG, IgA, and IgM) associated with a dysfunctional immune response. SAD is associated with recurrent infections in the setting of an insufficient response to polysaccharide vaccinations. Streptococcus pneumoniae is a well-established cause of respiratory infections in SAD. However, there has been a paucity of evidence of pneumococcal peritonitis in SAD patients, being reported as spontaneous in acquired immunodeficiency such as AIDS. We report the first case of S. pneumoniae-induced peritonitis as the presenting sign for SAD.

Prophylactic Antibiotics Versus Immunoglobulin Replacement in Specific Antibody Deficiency

PURPOSE

Prophylactic antibiotics (PA) and immunoglobulin replacement (IGRT) are commonly used in specific antibody deficiency (SAD); however, optimal treatment is not well-established. Our purpose is to compare treatment outcomes with IGRT and/or PA among SAD patients.

METHODS

A retrospective chart review of SAD patients treated at two tertiary centers between January 2012 and May 2017 was performed. Clinical and laboratory data, and rates of infections prior to and after treatment with IGRT or PA were analyzed. Descriptive analyses, between-group comparisons of rates of infection after 1 year of treatment, and a stepwise logistic regression model were employed to explore factors contributing to treatment outcomes.

RESULTS

We identified 65 SAD patients with mean age were 18 years (2-71 years). The baseline mean number of infections in the PA group and IGRT group was 4.71 (SD 3.15) and 7.73 (SD 6.65), respectively. Twenty-nine (44.6%) received IGRT, 7 (10.7%) received PA, 7 (10.7%) received both IGRT and PA, 15 (23.1%) failed PA and switched to IGRT, and 7 did not receive any specific treatment. After 1 year of treatment, the difference in the mean number of infections in PA vs. IGRT was not statistically significant [2.86 (2.73) vs. 4.44 (4.74), p = 0.27]. Reporting autoimmunity increased the odds for persistent infections (OR = 4.29; p = 0.047), while higher IgG levels decreased the odds for persistent infections (OR = 0.68, p = 0.018).

CONCLUSIONS

PA and IGRT are equally effective as first line in preventing infections in SAD patients. However, patients who fail PA would benefit from IGRT.

Defining Polysaccharide Antibody Deficiency: Measurement of Anti-Pneumococcal Antibodies and Anti-Salmonella typhi Antibodies in a Cohort of Patients with Recurrent Infections

BACKGROUND

The correlation between different methods for the detection of pneumococcal polysaccharide vaccine (PPV) responses to diagnose specific polysaccharide antibody deficiency (SAD) is poor and the criteria for defining a normal response lack consensus. We previously proposed fifth percentile (p5) values of PPV responses as a new cutoff for SAD.

OBJECTIVE

To analyze the association of SAD (determined by either World Health Organization (WHO)-standardized ELISA or multiplex bead-based assay) with abnormal response to Salmonella (S.) typhi Vi vaccination in a cohort of patients with recurrent infections.

METHODS

Ninety-four patients with a clinical history suggestive of antibody deficiency received PPV and S. typhi Vi vaccines. Polysaccharide responses to either 3 or 18 pneumococcal serotypes were measured by either the WHO ELISA or a multiplex in-house bead-based assay. Anti-S. typhi Vi IgG were measured by a commercial ELISA kit. Allohemagglutinins (AHA) were measured by agglutination method.

RESULTS

Based on the American Academy of Allergy, Asthma and Immunology (AAAAI) criteria for WHO ELISA, 18/94 patients were diagnosed with SAD and 22/93 based on serotype-specific p5 cutoffs for bead-based assay. The association between the two methods was significant, with 10 subjects showing abnormal response according to both techniques. Abnormal response to S. typhi Vi vaccination was found in 7 patients, 6 of which had SAD. No correlation was found between polysaccharide response and AHA, age, or clinical phenotype.

CONCLUSION

The lack of evidence-based gold standards for the diagnosis of SAD represents a challenge in clinical practice. In our cohort, we confirmed the insufficient correlation between different methods of specific PPV response measurement, and showed that the S. typhi Vi response was not contributive. Caution in the interpretation of results is warranted until more reliable diagnostic methods can be validated.

Focusing on Good Responders to Pneumococcal Polysaccharide Vaccination in General Hospital Patients Suspected for Immunodeficiency. A Decision Tree Based on the 23-Valent Pneumococcal IgG Assay

Background and Aim: Recently, the 23-valent IgG-assay was suggested as screening assay to identify poor responders to pneumococcal polysaccharide (PnPS)-vaccination with the serotype-specific assay as a second-line test. However, in a low pre-test probability general hospital setting predicting good responders could be more valuable to reduce the number of samples needing serotyping. Methods: Serotype-specific PnPS antibody-assays were performed for suspected immunodeficiency in two Dutch general hospitals (Jeroen Bosch Hospital, 's-Hertogenbosch; Elisabeth Tweesteden Hospital, Tilburg). 23-Valent PnPS antibody-assays were subsequently performed in archived material. Data were analyzed using receiver operating characteristic curves (AUC) and agreement indices (ICC). Results: Sera of 284 patients (348 samples) were included; 23-valent IgG-titres and the corresponding sum of PnPS-serotype specific antibodies showed moderate correlation (ICC = 0.63). In 232 conjugated-pneumococcal-vaccine-naïve patients (270 samples), a random 23-valent IgG-titer could discriminate between samples with and without ≥7/11, ≥7/13, or ≥6/9 pneumococcal serotypes when both cut-off values 0.35 and 1.0 μg/ml were used (AUC 0.86 and 0.92, respectively). All patients with a pre-immunization-titer ≥38.2 μg/ml and/or post-immunization-titer ≥96.1 μg/ml and none with a post-immunization-titer ≤38.5 μg/ml exhibited a good response to PnPS vaccination. Using these breakpoints as screening test to predict good responders, only 24% of patients would require further serotyping, as opposed to 68% if breakpoints to predict poor responders would have been used. Conclusion: In a low pre-test probability setting, the 23-valent IgG-assay proved to be a reliable screening test for good responders in conjugated-pneumococcal-vaccine-naïve patients, reducing the overall number of patient samples needing further serotyping, thus reducing overall costs of pneumococcal vaccination response assessment.

Laboratory Assays of Immune Cell Function in Immunodeficiencies

Laboratory assays of immune cell function are essential for understanding the type and function of immune defects. These assessments should be performed in conjunction with a detailed history and physical examination, which should guide the evaluation of patients with a suspected immune deficiency. Laboratory assays of immune cell function are critical for assessing and demonstrating the functional impact of genetic mutations. Advances in diagnostic techniques continue to expand the ability of clinicians and researchers to understand the complex immune pathophysiology that underlies these disorders.

Intravenous immunoglobulin therapy: a snapshot for the internist

Intravenous immunoglobulins are the cornerstone for the treatment of primary humoral immunodeficiencies and may be used for a great number of other autoimmune, neurological and hematological conditions as well. Given their wide application, the possibility of running across a patient who needs this kind of therapy is becoming increasingly common. Generally, intravenous immunoglobulins are well tolerated. However, numerous adverse reactions ranging from mild to severe have been reported and linked to patient- and product-related factors. For all these reasons, we present herein a comprehensive review of the on- and off-label applications of intravenous immunoglobulins and provide a guide for the internist how to minimize the risk of adverse reactions and manage them.

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.

Progress in mucosal immunization for protection against pneumococcal pneumonia

Introduction: Lower respiratory tract infections are the fourth cause of death worldwide and pneumococcus is the leading cause of pneumonia. Nonetheless, existing pneumococcal vaccines are less effective against pneumonia than invasive diseases and serotype replacement is a major concern. Protein antigens could induce serotype-independent protection, and mucosal immunization could offer local and systemic immune responses and induce protection against pneumococcal colonization and lung infection. Areas covered: Immunity induced in the experimental human pneumococcal carriage model, approaches to address the physiological barriers to mucosal immunization and improve delivery of the vaccine antigens, different strategies already tested for pneumococcal mucosal vaccination, including live recombinant bacteria, nanoparticles, bacterium-like particles, and nanogels as well as, nasal, pulmonary, sublingual and oral routes of vaccination. Expert opinion: The most promising delivery systems are based on nanoparticles, bacterial-like particles or nanogels, which possess greater immunogenicity than the antigen alone and are considered safer than approaches based on living cells or toxoids. These particles can protect the antigen from degradation, eliminating the refrigeration need during storage and allowing the manufacture of dry powder formulations. They can also increase antigen uptake, control release of antigen and trigger innate immune responses.

Common Variable Immune Deficiency and Associated Complications

Common variable immunodeficiency disorders refer to a relatively common primary immune deficiency group of diseases that present with infectious and inflammatory complications secondary to defects in antibody production and sometimes in cellular immunity. The disorder often presents in middle age or later with recurrent sinopulmonary infections, bronchiectasis, or a plethora of noninfectious complications such as autoimmune disorders, granulomatous interstitial lung disease, GI diseases, malignancies (including lymphoma), and multisystem granulomatous disease resembling sarcoidosis. Infusion of immunoglobulin by IV or subcutaneous is the mainstay of therapy. Management of complications is often difficult as immune suppression may be necessary in these conditions and entails the use of medications and biologicals which may further increase the risk for infections. Specifically, bronchiectasis, granulomatous lymphocytic interstitial lung disease, repeated sinopulmonary infections, and malignancies are sequelae of antibody deficiency that may present to the pulmonologist. This review will provide an updated understanding of the molecular aspects, differential diagnosis, presentations, and the management of common variable immunodeficiency disorders.