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.

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

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

Tolerability and Efficacy of s.c. IgG Self-Treatment in ME/CFS Patients with IgG/IgG Subclass Deficiency: A Proof-of-Concept Study

BACKGROUND

Chronic fatigue syndrome (ME/CFS) is a complex disease frequently triggered by infections. IgG substitution may have therapeutic effect both by ameliorating susceptibility to infections and due to immunomodulatory effects.

METHODS

We conducted a proof of concept open trial with s.c. IgG in 17 ME/CFS patients suffering from recurrent infections and mild IgG or IgG subclass deficiency to assess tolerability and efficacy. Patients received s.c. IgG therapy of 0.8 g/kg/month for 12 months with an initial 2 months dose escalation phase of 0.2 g and 0.4 g/kg/month.

RESULTS

Primary outcome was improvement of fatigue assessed by Chalder Fatigue Scale (CFQ; decrease ≥ 6 points) and of physical functioning assessed by SF-36 (increase ≥ 25 points) at month 12. Of 12 patients receiving treatment per protocol 5 had a clinical response at month 12. Two additional patients had an improvement according to this definition at months 6 and 9. In four patients treatment was ceased due to adverse events and in one patient due to disease worsening. We identified LDH and soluble IL-2 receptor as potential biomarker for response.

CONCLUSION

Our data indicate that self-administered s.c. IgG treatment is feasible and led to clinical improvement in a subset of ME/CFS patients.

Immunoglobulin deficiencies in treated patients suffering from rheumatoid arthritis

Immunoglobulins and antibodies to immunoglobulins (autoimmunoglobulins) have been identified to be implicated in the pathogenesis of rheumatoid arthritis (RA). Immunoglobulin deficiencies have been suggested to account for the increased risk of infections in RA patients. This study was carried out to determine the prevalence of immunoglobulin deficiencies in patients with RA and the identification of putative contributing factors. Immunoglobulin levels in blood samples of patients with rheumatoid arthritis were evaluated by an immunonephelometric assay. Demographic and disease related data (including age, sex, smoking habits, disease duration and activity, inflammatory markers) were assessed, and associations were identified by regression analysis. 539 patients were enrolled between 2011 and 2013. The most common immunoglobulin (Ig) deficiencies were those of IgM (24.5%) and IgG (19.9%). Most frequent deficiencies of subclasses were observed for IgG1 (42.3%), followed by IgG4 (10.4%), IgG2 (7.2%), and IgG3 (5.4%). Regression analyses revealed that deficiencies of IgM, IgG, IgG1, and IgG2 were more prevalent in older patients. In addition, smoking was associated with IgG2 deficiency, and IgA deficiency was associated with female sex. Occurrence of infections was significantly increased in patients with IgG, IgG2, and IgG4 deficiencies. RA patients displayed high rates of IgG and IgM deficiencies. In consequence, the assessment of immunoglobulin status should precede the application of immune modulating drugs to prevent a potential risk of infectious diseases. Prospective studies are needed to investigate the influence of immune modulating drugs on IgG and IgG subclass levels.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Differentiation of Common Variable Immunodeficiency From IgG Deficiency

BACKGROUND

Common variable immunodeficiency (CVID) and IgG deficiency are 2 of the more prevalent primary humoral immune defects. The former is defined by consensus with criteria for quantitative and qualitative antibody defects, whereas the latter is used to describe patients with reduced IgG, who commonly have recurrent sinopulmonary infections but do not fulfill CVID criteria. However, these patients are often given this diagnosis.

OBJECTIVE

To compare immunologic findings and clinical manifestations of 2 large cohorts of patients with CVID or IgG deficiency to better delineate differences between these syndromes.

METHODS

We extracted clinical and laboratory data from electronic medical records of patients at our institution who had received International Classification of Disease codes for either CVID, or IgG deficiency. We gathered immunoglobulin levels, lymphocyte subpopulation counts, and serological vaccine responses. In some patients, we performed flow cytometry to determine percentages of memory and switched-memory B cells. We compiled and statistically compared clinical data related to infectious manifestations, bronchiectasis, autoimmune diseases, infiltrative inflammatory processes, and lymphoid malignancies.

RESULTS

In contrast to IgG-deficient patients, we found that patients with CVID had lower IgG levels, greater unresponsiveness to most vaccines, lower percentages of memory and isotype switched-memory B cells, and lower CD4 T-cell counts. Clinically, patients with CVID presented similar rates of sinusitis and pneumonias, but a significantly higher prevalence of bronchiectasis and especially noninfectious complications.

CONCLUSIONS

CVID and IgG deficiency do not share the same disease spectrum, the former being associated with immunodysregulative manifestations and markers of a more severe immune defect. These data may allow clinicians to distinguish these conditions and the management differences that these patients pose.

Performance evaluation of serum IgG subclass quantification using a SPAPLUS turbidimetric analyzer and comparison with the BNII nephelometer

IgG consists of four subclasses: IgG1, IgG2, IgG3, and IgG4. Changes in the serum concentration of each subclass reflect different clinical situations, and quantification of each subclass is important to assess patients' clinical states. Herein, we evaluated the analytical performance of the SPAPLUS turbidimetric analyzer (The Binding Site, Birmingham, UK) for IgG subclass. Precision, linearity, comparison with the BNII system (Siemens Healthineers, Erlangen, Germany), and reference interval were assessed according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. The repeatability and within-laboratory precision were within 5% for all IgG subclasses. The coefficient of determination (R²) was higher than 0.99 for the analytical measurement range in all IgG subclasses. Comparison between SPAPLUS and BNII revealed significant differences in IgG1, IgG3, and IgG4 (p < .0001). IgG1 and IgG4 values were lower in SPAPLUS than BNII. On the other hand, IgG3 values were higher in SPAPLUS than BNII. The SPAPLUS turbidimetric analyzer exhibited good analytical performance for quantification of four IgG subclasses. Because of the differences between SPAPLUS and BNII, follow-up test for disease monitoring should be performed with same instrument.

Disorders of Humoral Immunity in Children with IgG Subclass Deficiency and Recurrent Respiratory Infections

Respiratory tract infections in children are one of the most common causes for medical consultations. When the infections are of recurring nature, they are a major reason for the diagnostics for primary immunodeficiency that is in about 65% of cases underlain by disorders of humoral immunity. This study seeks to retrospectively evaluate the history of recurrent respiratory tract infections in children with humoral disorders and the associations among deficiencies in the immune system components. We evaluated 394 children aged 3 months to 18 years. We found 49.5% (195 cases) of children with IgG deficiencies, all of whom had normal IgE levels. There were 8.4% (33 cases) of IgA deficiency, 7.4% (29 cases) of IgM insufficiency, and 4.1% (16 cases) of CD19+ cells deficiency. The elevated level of CD19+ cells was found in 27.7% (109 out of the 394 children). Immunoglobulin deficiencies often coexisted with a deficiency in another immunoglobulin class above outlined. There was an interdependence between IgA abnormality and IgG, IgG3, and IgG4 abnormalities as well as between IgM abnormality and IgG and IgG1 abnormalities. We conclude that respiratory tract infections in children are often underlain by a convergence of IgG with both IgA and IgM abnormal states. The physiopathological meaning of this convergence for the infection course and resulting functional respiratory changes remains elusive.

Common infusion-related reactions to subcutaneous immunoglobulin therapy: Managing patient expectations

OBJECTIVE

The availability of weekly subcutaneous infusions of subcutaneous immunoglobulin (SCIg) provides an additional therapeutic option for patients with primary immunodeficiency disease. With proper patient education, individuals can safely transition to SCIg therapy and experience minimal side effects.

RESEARCH DESIGN

Case reports.

RESULTS

A plan for successful implementation of SCIg therapy is presented. Case reports illustrate the how to manage the transition from IVIg to home infusion of SCIg. In Case 1, despite training, home infusion was complicated by infusion-site reactions, the most common adverse event. Troubleshooting by the medical staff identified improper administration of SCIg, a correctable cause of reactions. In Case 2, patient education enabled this woman to successfully transition to SCIg without adverse effects, and without the headache and fatigue she experienced with IVIg.

CONCLUSIONS

Home infusion of SCIg can be successfully implemented with careful planning, patient/caregiver education, support, and follow-up.