Immunoglobulin G Subclass Deficiencies in Adult Patients with Chronic Airway Diseases

Serum immunoglobulin levels in group E of chronic obstructive pulmonary disease: insights for clinical management and immunoglobulin therapy strategies

OBJECTIVE

The study aimed to characterize serum immunoglobulin (Ig) concentrations and their relationship with clinical and paraclinical features in patients with COPD group E in the stable stage. Additionally, the study focused on evaluating the relationship between serum Ig levels and the risk of exacerbations over the next 12 months, thereby clarifying the role of serum Ig deficiency in affecting the future risk for these patients.

METHODS

A prospective observational study assessed IgG, IgA, IgM, and IgE levels in 67 COPD patients and 30 healthy controls at Military Hospital 103 from October 2017 to August 2020. Primary outcomes included Ig isotype levels in COPD patients, with secondary outcomes exploring differences compared to controls and associations with clinical variables.

RESULTS

COPD patients showed significantly lower IgG concentrations and higher IgA levels than controls. IgM and IgE levels did not differ significantly. Subgroup analysis revealed notable decreases in IgG1 and IgG3 concentrations, with 10.4% of patients exhibiting reduced IgG levels and 0.3% diagnosed with common variable immunodeficiency. No significant associations were found between Ig levels and exacerbation risk or clinical variables.

CONCLUSIONS

Serum IgG and IgM concentrations were significantly reduced in COPD patients compared to normal individuals, with IgG1 and IgG3 concentrations notably low. Serum IgA levels were significantly higher in COPD patients compared with normal controls. However, no significant association was found between Ig concentrations, particularly serum IgG deficiency and its subclasses, with the frequency and risk of exacerbations during 12 months of longitudinal follow-up. Caution is warranted in the use of immunoglobulin therapy in the treatment of COPD patients.

TRIAL REGISTRATION

An independent ethics committee approved the study (Ethics Committee of Military Hospital 103 (No. 57/2014/VMMU-IRB), which was performed in accordance with the Declaration of Helsinki, Guidelines for Good Clinical Practice.

Suboptimal Response to Biologics in Severe Asthma-A Marker of Humoral Immunodeficiencies

BACKGROUND

Asthmatic patients with antibody deficiencies (AD) have more severe disease and higher risk of exacerbations. No data exist about the efficacy of biologics in severe asthma (SA) patients with AD.

OBJECTIVE

To evaluate the efficacy of biologics in SA patients with and without AD.

METHODS

A case-control real-life study was conducted including 68 patients divided into 2 groups: group 1 with SA-AD and group 2 with SA.

RESULTS

Treatment with biologics for 6 months was effective for decreasing the number of exacerbations, hospitalizations, and emergency department (ED) visits and improving the Asthma Control Questionnaire (ACQ) score; biologics also proved a systemic corticosteroid-sparing effect. Despite benefits, the number of exacerbations, hospitalizations, and ED visits, the mean ACQ score, and the cumulative dose of systemic corticosteroids remain higher in group 1 than in group 2, with lower lung function parameters. The rates of responses in group 1 were inferior to those in group 2, with a decrease by ≥50% of exacerbation rate in 76% versus 97% of patients (P = .006), no hospitalization in 44% versus 91% of patients (P < .001), no ED visit in 56% versus 82% of patients (P = .018), a significant improvement of the ACQ score by ≥0.5 in 68% versus 100% of patients (P < .001), and an increase of forced expiratory volume in the first second by >10% in 32% versus 65% of patients (P = .007).

CONCLUSIONS

Despite evident benefits, SA patients with AD have suboptimal responses to biologics compared with those immunocompetent. A multidisciplinary approach is necessary to optimize the management of these patients in practice.

Current Issues in the Management of IgG Subclass Deficiencies in Adults With Chronic Respiratory Diseases

Primary immunodeficiency diseases (PIDs) are uncommon in adults; however, immunoglobulin G subclass deficiency (IGGSCD) is often found in a subset of adult patients with chronic respiratory diseases. As quantitative laboratory tests are used to diagnose IGGSCD, the clinical significance of IGGSCD remains controversial. However, respiratory infection is a common presenting feature of IGGSCD, and respiratory complications are responsible for subsequent morbidities, such as severe asthma, bronchiectasis, chronic obstructive airway diseases, and mortality. This review summarizes the current epidemiological data for PIDs, focusing on IGGSCD in the adult population. In addition, the investigation, treatment, and management strategies are detailed, including distinct issues faced by patients with chronic airway disease and their physicians in the proper diagnosis and treatment of IGGSCD.

Clinical and laboratory evaluation of Turkish children with IgG subclass deficiency

BACKGROUND

IgG subclass deficiency is a laboratory diagnosis and becomes important with recurrent infections. This study aimed to examine the demographic, clinical, and laboratory results of pediatric cases with IgG subclass deficiency and to improve the understanding of the clinical significance of IgG subclass deficiency.

METHODS

In this study, the clinical and laboratory features of 111 pediatric patients, with at least one whose serum IgG subclasses was measured as lower than 2 standard deviation of healthy aged-matched control values, were evaluated. The clinical and laboratory features of the cases with isolated IgG subclass deficiency (Group 1) and those with low serum levels of any of IgG, IgA, and IgM in addition to the IgG subclass deficiency (Group 2) were compared.

RESULTS

A total of 55 (49.54%) and 56 (50.45%) patients were included in Groups 1 and 2, respectively. Among our studied cases, 20 (18.1%) had a history of hospitalization in the neonatal period, 61 (54.95%) had at least one hospitalization due to infection, and 55 (49.54%) had a history of recurrent infection. The frequencies of these three conditions were statistically significantly higher in Group 2 (p < 0.05). The frequencies of infections in the last year in Groups 1 and 2 were 4.4 ± 1.2 and 5.4 ± 1.9, respectively (p < 0.05). As a result of recurrent infections, 43.24% (n = 48) of our patients received antibiotic prophylaxis, and 21.62% (n = 24) had immunoglobulin replacement therapy. Furthermore, the numbers of patients who needed these treatments were higher in Group 2 (p < 0.05).

CONCLUSION

In cases with IgG subclass deficiencies, concomitant main-group immunoglobulin deficiencies may increase the number and severity of infections, leading to hospitalizations, antibiotic prophylaxis, and immunoglobulin therapy. More attention should be paid to cases of immunoglobulin main-group deficiencies in the follow-up of these cases.

Changes in Serum Immunoglobulin G Subclasses during the Treatment of Patients with Chronic Obstructive Pulmonary Disease with Infectious Exacerbations

Introduction: Despite the theoretical importance of serum immunoglobulin (Ig) in the outcome of COPD exacerbations, the existing evidence for this has not been enough. This study was performed to evaluate changes in serum Ig levels and their relationship with outcomes of acute infectious exacerbations in patients with COPD. Methods: The prospective study was conducted at Military Hospital 103 from August 2017 to April 2019. Group D patients with COPD with infectious exacerbation were selected for participation in the study. The control group consisted of 30 healthy people. The patients were provided clinical examination and laboratory service; simultaneously, we measured their serum Ig levels (total IgG, IgG1, IgG2, IgG3, IgG4) at two time points: at admission (T1) and the final health outcome (T2). Results: The median levels of total IgG in patients at times T1 and T2 were significantly lower compared with those in the healthy group (1119.3 mg/dL and 1150.6 mg/dL compared with 2032.2 mg/dL) (p < 0.001). Regarding changes among IgG subclasses, the IgG1, IgG3, and IgG4 levels measured at T1 and T2 were reduced significantly compared with the control group (p < 0.05); the IgG3 levels at T1 were significantly higher than those at T2. IgG3 levels in patients with life-threatening exacerbations were significantly lower than the remaining ones (24.6 (26.8−155.5) mg/dL and 25.6 (29.5−161.2) mg/dL, respectively, p = 0.023). Conclusions: In group D patients with COPD with infectious exacerbations, there was a decrease in the serum IgG, IgG1, IgG3, and IgG4 levels. IgG3 levels were associated with the severity of COPD exacerbation.

The impact of IgG subclass deficiency on the risk of mortality in hospitalized patients with COPD

Background

Immunoglobulin G (IgG) deficiency increases the risk of acute exacerbations and mortality in chronic obstructive pulmonary disease (COPD). However, the impact of IgG subclass deficiency on mortality in COPD is unknown. Here, we determined which IgG subclass, if any, is associated with increased risk of mortality in COPD.

Methods

We measured serum IgG subclass concentrations of 489 hospitalized patients with COPD who were enrolled in the Rapid Transition Program (clinicaltrials.gov identifier NCT02050022). To evaluate the impact of IgG subclass deficiency on 1-year mortality, Cox proportional hazards regression analyses were performed with adjustments for potential confounders.

Results

Deficiencies in IgG1, IgG2, IgG3, and IgG4 were present in 1.8%, 12.1%, 4.3%, and 11.2% of patients, respectively. One-year mortality was 56% in patients with IgG1 deficiency, 27% in IgG2 deficiency, 24% in IgG3 deficiency, and 31% in IgG4 deficiency. Cox proportional modeling showed that IgG1 and IgG4 deficiencies increased the 1-year mortality risk with an adjusted hazard ratio of 3.92 (95% confidence interval [CI] = 1.55–9.87) and 1.74 (95% CI = 1.02–2.98), respectively. Neither IgG2 nor IgG3 deficiency significantly increased 1-year mortality. Two or more IgG subclass deficiencies were observed in 5.3%. Patients with 2 or more IgG subclass deficiencies had a higher 1-year mortality than those without any deficiencies (46.2% vs. 19.7%, p < 0.001), with an adjusted hazard ratio of 2.22 (95% CI = 1.18–4.17).

Conclusions

IgG1 and IgG4 deficiency was observed in 1.8% and 11.2% of hospitalized patients with COPD, respectively, and these deficiencies were associated with a significantly increased risk of 1-year mortality.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02052-3.

Potent TRIM21 and complement-dependent intracellular antiviral immunity requires the IgG3 hinge

Humans have four IgG antibody subclasses that selectively or differentially engage immune effector molecules to protect against infections. Although IgG1 has been studied in detail and is the subclass of most approved antibody therapeutics, increasing evidence indicates that IgG3 is associated with enhanced protection against pathogens. Here, we report that IgG3 has superior capacity to mediate intracellular antiviral immunity compared with the other subclasses due to its uniquely extended and flexible hinge region, which facilitates improved recruitment of the cytosolic Fc receptor TRIM21, independently of Fc binding affinity. TRIM21 may also synergize with complement C1/C4-mediated lysosomal degradation via capsid inactivation. We demonstrate that this process is potentiated by IgG3 in a hinge-dependent manner. Our findings reveal differences in how the four IgG subclasses mediate intracellular immunity, knowledge that may guide IgG subclass selection and engineering of antiviral antibodies for prophylaxis and therapy.

Hydroxychloroquine Therapy and Serum Immunoglobulin Levels in Women with IgG Subclass Deficiency and Systemic Lupus Erythematosus, Sjögren Syndrome, and Rheumatoid Arthritis: A Retrospective Study

Hydroxychloroquine (HCQ) therapy decreased immunoglobulin (Ig) levels in patients with Sjögren syndrome (SS) and rheumatoid arthritis (RA) in previous studies. We found no report of Ig levels of women with IgG subclass deficiency (IgGSD) and systemic lupus erythematosus (SLE), SS, or RA treated with HCQ. We retrospectively evaluated IgG, IgG subclass, IgA, and IgM levels and other characteristics of women at IgGSD diagnosis who did and did not take HCQ for SLE, SS, or RA. There were 132 women (48 subnormal IgG1 only, 49 combined subnormal IgG1/IgG3, and 35 subnormal IgG3 only). Mean age was 49 ± 13 years. Twenty-two women with SLE, SS, RA, or combination thereof reported HCQ ≥ 200 mg/day ≥ 6 months. In each IgGSD subtype, median Ig levels of women who took HCQ were not significantly lower than those of women who did not take HCQ. Women with combined subnormal IgG1/IgG3 who took HCQ had greater median IgG2 than women who did not take HCQ (4.89 g/L (range 4.43, 4.94) vs. 2.57 g/L (1.21, 6.44), respectively; p = 0.0123). Regressions on IgG1, IgG2, and IgG3 revealed positive associations with HCQ therapy (p = 0.0043, 0.0037, and 0.0139, respectively). There were no significant Ig associations with age, SLE, SS, or RA as independent variables. HCQ therapy of SLE, SS, or RA in women with IgGSD was not associated with significantly lower IgG, IgG subclass, IgA, or IgM levels. IgG1, IgG2, and IgG3 were positively associated with HCQ therapy, after adjustment for other variables.

Lung Function and Health Status in Individuals with Severe Alpha-1-Antitrypsin Deficiency at the Age of 42

Background

Severe hereditary alpha-1-antitrypsin deficiency (AATD) is a known risk factor for the early development of pulmonary emphysema and COPD, especially in smokers. By the Swedish national screening programme carried out from 1972 to 1974, a cohort of individuals with severe (PiZZ) AATD was identified and has been followed up regularly. The aim of this study was to investigate health status, quality of life and lung function in this cohort at the age of 42 years compared with an age-matched control group randomly selected from the population registry.

Methods

All study participants answered a questionnaire on smoking habits, symptoms, occupation, exposure to airway irritants and quality of life using Saint George’s Respiratory Questionnaire (SGRQ). They underwent complete pulmonary function tests (PFT) and forced oscillation technique (FOT) for the measurement of airway resistance and reactance. Blood samples were taken for allergies and IgG-subclasses as an indicator of increased risk of airway infections.

Results

The residual volume (RV), total lung capacity (TLC) and RV/TLC ratio were significantly higher in the PiZZ ever-smokers compared to the PiMM ever-smokers and PiZZ never-smokers (p < 0.05). The resistance in the upper, small and total airways was significantly lower in PiZZ subjects compared to PiMM subjects (p < 0.05). A greater proportion of PiZZ never-smokers had an FEV₁/VC ratio <0.7 than PiMM never-smokers (p = 0.043). PiZZ subjects with occupational exposure to airway irritants showed a significantly lower FEV₁, VC and higher RV/TLC ratio than PiMM individuals with exposure (p < 0.05).

Conclusion

At the age of 42, ever-smoking PiZZ individuals have signs of COPD, and also PiZZ never-smokers have early, physiological signs of emphysema.

Association of mannose-binding lectin, ficolin-2 and immunoglobulin concentrations with future exacerbations in patients with chronic obstructive pulmonary disease: secondary analysis of the randomized controlled REDUCE trial

BACKGROUND

The innate and adaptive immune system is involved in the airway inflammation associated with acute exacerbations in patients with chronic obstructive pulmonary disease (COPD). We evaluated the association of mannose-binding lectin (MBL), immunoglobulin (Ig) and ficolin-2 concentrations with COPD exacerbations and according to the glucocorticoid treatment duration for an index exacerbation.

METHODS

Post-hoc analysis of the randomized, double-blind, placebo-controlled REDUCE trial of 5 vs. 14 days of glucocorticoid treatment for an index exacerbation. MBL, ficolin-2 and total IgG/IgA and subclass concentrations were determined in stored samples drawn (n = 178) 30 days after the index exacerbation and associated with the risk of re-exacerbation during a 180-day follow-up period.

RESULTS

IgG and subclass concentrations were significantly lower after 14 days vs. 5 days of glucocorticoid treatment. Patients with higher MBL concentrations were more likely to suffer from a future exacerbation (multivariable hazard ratio 1.03 per 200 ng/ml increase (95% confidence interval (CI) 1.00-1.06), p = 0.048), whereas ficolin-2 and IgG deficiency were not associated. The risk was most pronounced in patients with high MBL concentrations, IgG deficiency and 14 days of glucocorticoid treatment pointing towards an interactive effect of MBL and IgG deficiency in the presence of prolonged glucocorticoid treatment duration [Relative excess risk due to interaction 2.13 (95% CI - 0.41-4.66, p = 0.10)]. IgG concentrations were significantly lower in patients with frequent re-exacerbations (IgG, 7.81 g/L vs. 9.53 g/L, p = 0.03).

CONCLUSIONS

MBL modified the short-term exacerbation risk after a recent acute exacerbation of COPD, particularly in the setting of concurrent IgG deficiency and recent prolonged systemic glucocorticoid treatment. Ficolin-2 did not emerge as a predictor of a future exacerbation risk.

Coming together at the hinges: Therapeutic prospects of IgG3

The human IgG3 subclass is conspicuously absent among the formats for approved monoclonal antibody therapies and Fc fusion protein biologics. Concern about the potential for rapid degradation, reduced plasma half-life, and increased immunogenicity due to marked variation in allotypes has apparently outweighed the potential advantages of IgG3, which include high affinity for activating Fcγ receptors, effective complement fixation, and a long hinge that appears better suited for low abundance targets. This review aims to highlight distinguishing features of IgG3 and to explore its functional role in the immune response. We present studies of natural immunity and recombinant antibody therapies that elucidate key contributions of IgG3 and discuss historical roadblocks that no longer remain clearly relevant. Collectively, this body of evidence motivates thoughtful reconsideration of the clinical advancement of this distinctive antibody subclass for treatment of human diseases. Abbreviations: ADCC - Antibody-Dependent Cell-mediated CytotoxicityADE - Antibody-dependent enhancementAID - Activation-Induced Cytidine DeaminaseCH - Constant HeavyCHF - Complement factor HCSR - Class Switch RecombinationEM - Electron MicroscopyFab - Fragment, antigen bindingFc - Fragment, crystallizableFcRn - Neonatal Fc ReceptorFcγR - Fc gamma ReceptorHIV - Human Immunodeficiency VirusIg - ImmunoglobulinIgH - Immunoglobulin Heavy chain geneNHP - Non-Human Primate.

Low immunoglobulin G4 subclass level is associated with recurrent wheezing in young children

Background

The most important infectious trigger of asthma is the virus and patients with immunoglobulin deficiencies are prone to recurrent respiratory infections.

Objective

We investigated the relationship between immunoglobulin G subclass and recurrent respiratory symptom exacerbation and explored possible therapeutic effects of intravenous immunoglobulin administration.

Methods

Twenty-eight infants less than 24 months old with 2 or more recurrent wheezing episodes (infantile wheezer group) and 29 asthmatic children aged 24 months to 15 years (bronchial asthma [B-asthma] group) visited our hospital from October 2010 to January 2018. Serum immunoglobulin G, A, M, E, G1, G2, G3, and G4 were measured in each group and compared. In both groups, serum immunoglobulin and symptoms were compared before and after intravenous immunoglobulin administration.

Results

The 2 study groups exhibited several statistically significant differences when comparing respiratory virus infection rate (p < 0.001), coinfection rate (p < 0.0001), most commonly found viral infection (human bocavirus vs. human rhinovirus), and immunoglobulin A (p < 0.001), E (p = 0.008), G2 (p < 0.001), and G4 (p = 0.011) levels. In the infantile wheezer group, there was an inverse correlation between immunoglobulin G4 levels and wheezing numbers (R = -0.5538, P = 0.0022). Both groups showed significant changes in immunoglobulin levels and respiratory symptom exacerbations (recurrent wheezing, shortness of breath, chest tightness, cough, and fever) over 1 year after intravenous immunoglobulin administration.

Conclusion

There was an association between recurrent wheezing and specific immunoglobulin G deficiencies. We suggest that intravenous immunoglobulin therapy significantly elevates specific immunoglobulin G levels though it lasts only for short term and might be associated with decreased respiratory symptoms. Therefore, low IgG4 levels among infants with recurrent wheezing may be indicative for intravenous immunoglobulin therapy.

Characterization of adult patients with IgG subclass deficiency and subnormal IgG2

Background

Adults with IgG subclass deficiency (IgGSD) with subnormal IgG2 are inadequately characterized.

Methods

We retrospectively analyzed observations in unrelated adults with IgGSD evaluated in a single hematology clinic (1991–2019) and selected those with subnormal serum IgG2 (<117 mg/dL (<1.2 g/L)) without corticosteroid therapy to describe: age; prevalence of women; upper/lower respiratory infection; autoimmune condition(s); atopy; other allergy; frequent or severe respiratory tract infection in first-degree relatives; IgG, IgG subclasses, IgA, and IgM; blood lymphocyte subpopulations; human leukocyte antigen (HLA)-A and -B types and haplotypes; and 23-valent pneumococcal polysaccharide vaccination (PPSV23) responses. We determined the prevalence of subnormal IgG2 among unrelated adults with IgGSD without corticosteroid therapy and compared general characteristics of those with and without subnormal IgG2.

Results

There were 18 patients (94.4% women) with subnormal IgG2. Mean age was 52 ± 11 y. Upper/lower respiratory infection occurred in 94.4%/74.8%, respectively. Autoimmune condition(s), atopy, other allergy, and frequent or severe respiratory infection in first-degree relatives occurred in 44.4%, 44.4%, 61.1%, and 22.2%, respectively. Median IgG2 was 105 mg/dL (83, 116). Subnormal IgG, IgG1, IgG3, IgG4, IgA, and IgM was observed in 66.7%, 50.0%, 100.0%, 5.6%, 33.3%, and 0%, respectively. Lymphocyte subpopulations were normal in most patients. HLA frequencies were similar in patients and controls. Three of 4 patients had no protective S. pneumoniae serotype-specific IgG levels before or after PPSV23. These 18 patients represent 7.6% of 236 adults with IgGSD. Prevalence of subnormal IgG, subnormal IgG3, and subnormal IgA was significantly greater in 18 adults with subnormal IgG2 than 218 adults without subnormal IgG2. Prevalence of subnormal IgM was significantly lower in patients with subnormal IgG2.

Conclusions

Characteristics of adults with IgGSD with subnormal IgG2 include female predominance, other immunologic abnormalities, subnormal IgG3 and/or IgG1, lack of HLA-A and -B association, and suboptimal PPSV23 response.

Efficacy of immunoglobulin replacement therapy and azithromycin in severe asthma with antibody deficiency

BACKGROUND

Although antibody deficiency (AD) is a well-known cause of recurrent respiratory infections, there are few data on its impact in adults with asthma. The objective of the present study was to assess outcomes in adults with severe asthma and AD after treatment with either azithromycin or subcutaneous immunoglobulins (SCIg).

METHODS

We performed a 5-year, prospective, observational, two-centre study of adults with severe asthma and AD in France. Bronchiectasis was ruled out by high-resolution computed tomography. Patients were treated for one year with either azithromycin (250 mg every other day) or SCIg (0.4-0.6 g/kg/months, weekly). All patients were evaluated for exacerbations, asthma control and lung function at baseline and then one year after treatment initiation.

RESULTS

Thirty-nine patients with severe asthma were included in the study: 14 had been treated with azithromycin and 25 had been treated with SCIg. Before the initiation of treatment for AD, all patients had an Asthma Control Questionnaire (ACQ-7) score > 1.5 (mean ± SD: 2.71 ± 0.53) despite treatment at GINA step 4 or 5, and had a high exacerbation rate requiring oral corticosteroids and/or rescue antibiotics (∼7.2 ± 2.1/patient/year). One year after treatment initiation, we observed a significantly higher FEV1 (mean: 0.18 ± 0.22 L) and ACQ-7 score (1.26 ± 0.68), and a significantly lower exacerbation rate (1.63 ± 1.24/patient/year).

CONCLUSIONS

Treatment of AD dramatically improved asthma outcomes - suggesting that adults with severe asthma and recurrent respiratory infections should be screened and (if appropriate) treated for AD.

Reconstitution of IgG Subclasses following Immunoglobulin Therapy in Adult Primary Hypogammaglobulinemia

BACKGROUND

Immunoglobulin (Ig) therapy is highly effective in reducing the frequency and severity of infections. However, a subset of patients does not respond adequately.

OBJECTIVE

To determine in adult patients with primary hypogammaglobulinemia (a) if failure to reconstitute IgG subclass(es) is associated with inadequate clinical response, (b) whether reconstitution of IgG subclasses differs between routes of Ig administration, (c) which subclasses contribute to low total IgG, and (d) what are the most commonly impaired Streptococcus pneumoniae serotypes.

METHODS

A retrospective review of the records of patients with primary hypogammaglobulinemia followed up at the Immunology Clinic between 2010 and 2018 was conducted. Demographic, clinical, and laboratory data were collected.

RESULTS

Seventy-one patients with primary hypogammaglobulinemia were included. All subclasses were reconstituted in 85% of the patients. IgG3 and IgG4 were most commonly not reconstituted. Reconstitution occurred in 85% of the patients on intravenous Ig (IVIG), 81% of the patients on conventional subcutaneous Ig (SCIG), and 100% of the patients on enzyme-facilitated subcutaneous Ig (fSCIG). The annual infection rate was 0.87 with IVIG, 0.88 with conventional SCIG, and 0.6 with fSCIG. IgG subclasses contributing to low total IgG included IgG1 (61%), IgG2 (49%), IgG3 (23%), and IgG4 (28%). In patients with concomitant specific antibody deficiency (n = 47), the most commonly impaired antibody responses were against pneumococcal serotypes 3, 4, 6b, 12f, and 23f.

CONCLUSIONS

Failure to reconstitute subclasses does not correlate with an inadequate clinical response to immunoglobulin therapy in primary hypogammaglobulinemia. Full reconstitution of IgG subclasses was observed with fSCIG. A smaller panel of pneumococcal antibody responses may be used to define specific antibody deficiency.

Appropriate lung management in patients with primary antibody deficiencies

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

Duration of frequent or severe respiratory tract infection in adults before diagnosis of IgG subclass deficiency

Many adults with IgG subclass deficiency (IgGSD) experience long intervals of frequent/severe respiratory tract infection before IgGSD diagnosis, but reasons for delays in IgGSD diagnoses are incompletely understood. We performed a retrospective study of 300 white adults (ages ≥18 y) with IgGSD including frequency analyses of age at IgGSD diagnosis, duration of frequent/severe respiratory tract infection before IgGSD diagnosis, and age at onset of frequent/severe infection (calculated). We performed multivariable regressions on age at diagnosis, infection duration, and age at infection onset using these variables, as appropriate: sex; age at diagnosis; diabetes; autoimmune condition(s); atopy; allergy; corticosteroid use; body mass index; serum immunoglobulin isotype levels; blood lymphocyte subsets; three IgGSD-associated human leukocyte antigen-A and -B haplotypes; and referring physician specialties. Mean age at diagnosis was 50 ± 12 (standard deviation) y (median 50 y (range 19–79)). There were 247 women (82.3%). Mean infection duration at IgGSD diagnosis was 12 ± 13 y (median 7 y (range 1–66)). Mean age at infection onset was 38 ± 16 y (median 38 y (range 4, 76)). Age at infection onset was ≥18 y in 95.7% of subjects. Regressions on age at diagnosis and infection duration revealed no significant associations. Regression on age at infection onset revealed one positive association: age at diagnosis (p <0.0001). We conclude that the median duration of frequent/severe respiratory tract infection in adults before IgGSD diagnosis was 7 y. Older adults may be diagnosed to have IgGSD after longer intervals of infection than younger adults. Duration of frequent/severe respiratory tract infection before IgGSD diagnosis was not significantly associated with routine clinical and laboratory variables, including referring physician specialties.

The broad spectrum of lung diseases in primary antibody deficiencies

Human primary immunodeficiency diseases (PIDs) represent a heterogeneous group of more than 350 disorders. They are rare diseases, but their global incidence is more relevant than generally thought. The underlying defect may involve different branches of the innate and/or adaptive immune response. Thus, the clinical picture may range from severe phenotypes characterised by a broad spectrum of infections to milder infectious phenotypes due to more selective (and frequent) immune defects. Moreover, infections may not be the main clinical features in some PIDs that might present with autoimmunity, auto-inflammation and/or cancer. Primary antibody deficiencies (PADs) represent a small percentage of the known PIDs but they are the most frequently diagnosed, particularly in adulthood. Common variable immunodeficiency (CVID) is the most prevalent symptomatic PAD.

PAD patients share a significant susceptibility to respiratory diseases that represent a relevant cause of morbidity and mortality. Pulmonary complications include acute and chronic infection-related diseases, such as pneumonia and bronchiectasis. They also include immune-mediated interstitial lung diseases, such as granulomatous-lymphocytic interstitial lung disease (GLILD) and cancer. Herein we will discuss the main pulmonary manifestations of PADs, the associated functional and imaging findings, and the relevant role of pulmonologists and chest radiologists in diagnosis and surveillance.

The spectrum of lung complications in primary antibody deficiency ranges from asthma or COPD to extremely rare and specific ILDs. Early diagnosis of the underlying immune defect might significantly improve patients' lung disease, QoL and long-term prognosis.http://ow.ly/5cP230kZvOB

Serum IgG subclass levels and risk of exacerbations and hospitalizations in patients with COPD

BACKGROUND

The literature is scarce regarding the prevalence and clinical impact of IgG subclass deficiency in COPD. We investigated the prevalence of IgG subclass deficiencies and their association with exacerbations and hospitalizations using subjects from two COPD cohorts.

METHODS

We measured IgG subclass levels using immunonephelometry in serum samples from participants enrolled in two previous COPD trials: Macrolide Azithromycin for Prevention of Exacerbations of COPD (MACRO; n = 976) and Simvastatin for the Prevention of Exacerbations in Moderate-to-Severe COPD (STATCOPE; n = 653). All samples were collected from clinically stable participants upon entry into both studies. IgG subclass deficiency was diagnosed when IgG subclass levels were below their respective lower limit of normal: IgG1 < 2.8 g/L; IgG2 < 1.15 g/L; IgG3 < 0.24 g/L; and IgG4 < 0.052 g/L. To investigate the impact of IgG subclass levels on time to first exacerbation or hospitalization, we log-transformed IgG levels and performed Cox regression models, with adjustments for confounders.

RESULTS

One or more IgG subclass deficiencies were found in 173 (17.7%) and 133 (20.4%) participants in MACRO and STATCOPE, respectively. Lower IgG1 or IgG2 levels resulted in increased risk of exacerbations with adjusted hazard ratios (HR) of 1.30 (95% CI, 1.10-1.54, p < 0.01) and 1.19 (95% CI, 1.05-1.35, p < 0.01), respectively in the MACRO study, with STATCOPE yielding similar results. Reduced IgG1 or IgG2 levels were also associated with increased risk of hospitalizations: the adjusted HR for IgG1 and IgG2 was 1.52 (95% CI: 1.15-2.02, p < 0.01) and 1.33 (95% CI, 1.08-1.64, p < 0.01), respectively for the MACRO study; in STATCOPE, only IgG2 was an independent predictor of hospitalization. In our multivariate Cox models, IgG3 and IgG4 levels did not result in significant associations for both outcomes in either MACRO or STATCOPE cohorts.

CONCLUSIONS

Approximately 1 in 5 COPD patients had one or more IgG subclass deficiencies. Reduced IgG subclass levels were independent risk factors for both COPD exacerbations (IgG1 and IgG2) and hospitalizations (IgG2) in two COPD cohorts.

TRIAL REGISTRATION

This study used serum samples from participants of the MACRO ( NCT00325897 ) and STATCOPE ( NCT01061671 ) trials.

Primary immune deficiency diseases as unrecognized causes of chronic respiratory disease

BACKGROUND

More than half of all primary immune deficiency diseases (PIDD) affect antibody production and are well known as causes of recurrent sinusitis and lung infections. Chronic and recurrent infections of the upper and/or lower airways can contribute to inflammatory and obstructive processes in the lower airways which are initially reversible and considered "asthma", but can eventually cause irreversible remodeling and chronic obstructive pulmonary disease (COPD). Conversely, several lines of evidence suggest that many patients who present with a diagnosis of asthma have an increased incidence of infection, suggesting underlying host-defense defects. Asthma and respiratory infections in the first decades of life are recognized as risk factors for development of COPD, but when patients present with COPD as adults, underlying primary immune deficiency disease may be unrecognized.

MAIN FINDINGS AND CONCLUSIONS

Detection of PIDD as a potentially treatable underlying contributor to recurrent/acute exacerbations and morbidity of COPD, and provision of immunoglobulin (Ig) G replacement therapy, when appropriate, may decrease the progression of COPD. Decreasing the severity and rate of exacerbations and admissions should improve the quality of life and longevity of an important subset of patients with COPD, while decreasing costs. Major steps toward achieving these goals include developing a high index of suspicion, more frequent use and appropriate interpretation of screening tests such as quantitative immunoglobulins and vaccine responses, and prompt institution of IgG replacement therapy when antibody deficiency has been diagnosed.

The Pneumocell-study: Vaccination of IgG1- and IgG2-deficient patients with Prevnar13

BACKGROUND

Patients with IgG-deficiency often suffer from repeated bacterial infections with S. pneumoniae. Since there is a lack of knowledge regarding whether IgG-deficient patients would benefit from conjugate pneumococcal vaccination, we set out to evaluate the effect of Prevnar13 vaccination in IgG₁- and/or IgG₂-deficient patients.

METHOD

We designed a small pilot-study including IgG₁- and/or IgG₂-deficient patients (n=10) and age- and sex-matched healthy controls (n=10). Serum, plasma and heparin-blood were collected prior to vaccination, as well as 1, 2 and 4weeks post vaccination, and the levels of opsonophagocytic activity (Opa) titers and anti-pneumococcal IgG-antibodies were analyzed.

RESULTS

Patients generally had lower Opa-titers than controls for most serotypes, but they exhibited an almost normal vaccine response to serotypes 6A and 6B. Notably, 5/10 patients showed vaccine-response to at least one serotype. Most patients reached the presumably protective levels of Opa-titers ≥8 and anti-pneumococcal IgG levels of 0.35µg/ml by 4weeks post-vaccination for a majority of the serotypes.

CONCLUSION

Our results show that vaccination of IgG-deficient patients with Prevnar13 is likely to have a clinical benefit. Our initial findings will provide a framework for future vaccine-trials in this vulnerable patient group. Registered at www.clinicaltrials.gov as NCT01847781.

Effects of Immunoglobulin Replacement on Asthma Exacerbation in Adult Asthmatics with IgG Subclass Deficiency

Purpose

Recurrent respiratory tract infection is a common manifestation of primary immunodeficiency disease, and respiratory viruses or bacteria are important triggers of asthma exacerbations. Asthma often coexists with humoral immunodeficiency in adults, and some asthmatics with immunoglobulin (Ig) G subclass deficiency (IgGSCD) suffer from recurrent exacerbations. Although some studies suggest a benefit from Ig replacement, others have failed to support its use. This study aimed to assess the effect of Ig replacement on asthma exacerbation caused by respiratory infection as well as the asthma control status of adult asthmatics with IgGSCD.

Methods

This is a multi-center, open-label study of adult asthmatics with IgGSCD. All patients received monthly intravenous immunoglobulin (IVIG) for 6 months and were evaluated regarding asthma exacerbation related to infection, asthma control status, quality of life, and lung function before and after IVIG infusion.

Results

A total of 30 patients were enrolled, and 24 completed the study. Most of the patients had a moderate degree of asthma severity with partly (52%) or uncontrolled (41%) status at baseline. IVIG significantly reduced the proportion of patients with asthma exacerbations, lowered the number of respiratory infections, and improved asthma control status, compared to the baseline values (P<0.001). The mean asthma-specific quality of life and asthma control test scores were improved significantly (P=0.009 and P=0.053, respectively); however, there were no significant changes in lung function.

Conclusions

IVIG reduced the frequency of asthma exacerbations and improved asthma control status in adult asthmatics with IgGSCD, suggesting that IVIG could be an effective treatment option in this population.