Serum immunoglobulins and risk of infection: how low can you go?

Vaccinations in patients with chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is characterized by immune dysfunction resulting in heightened susceptibility to infections and elevated rates of morbidity and mortality. A key strategy to mitigate infection-related complications has been immunization against common pathogens. However, the immunocompromised status of CLL patients poses challenges in eliciting an adequate humoral and cellular immune response to vaccination. Most CLL-directed therapy disproportionately impairs humoral immunity. Vaccine responsiveness also depends on the phase and type of immune response triggered by immunization. In this review, we discuss the immune dysfunction, vaccine responsiveness, and considerations for optimizing vaccine response in patients with CLL.

Drugs Targeting CD20 in Multiple Sclerosis: Pharmacology, Efficacy, Safety, and Tolerability

Currently, there are four monoclonal antibodies (mAbs) that target the cluster of differentiation (CD) 20 receptor available to treat multiple sclerosis (MS): rituximab, ocrelizumab, ofatumumab, and ublituximab. B-cell depletion therapy has changed the therapeutic landscape of MS through robust efficacy on clinical manifestations and MRI lesion activity, and the currently available anti-CD20 mAb therapies for use in MS are a cornerstone of highly effective disease-modifying treatment. Ocrelizumab is currently the only therapy with regulatory approval for primary progressive MS. There are currently few data regarding the relative efficacy of these therapies, though several clinical trials are ongoing. Safety concerns applicable to this class of therapeutics relate primarily to immunogenicity and mechanism of action, and include infusion-related or injection-related reactions, development of hypogammaglobulinemia (leading to increased infection and malignancy risk), and decreased vaccine response. Exploration of alternative dose/dosing schedules might be an effective strategy for mitigating these risks. Future development of biosimilar medications might make these therapies more readily available. Although anti-CD20 mAb therapies have led to significant improvements in disease outcomes, CNS-penetrant therapies are still needed to more effectively address the compartmentalized inflammation thought to play an important role in disability progression.

Effects of donation frequency on U.S. source plasma donor health

BACKGROUND

Plasma-derived medicinal products (PDMPs) are essential, life-saving medicines manufactured from plasma donated by healthy human volunteers. PDMPs are used to treat a range of rare, serious, and chronic conditions, often genetic in origin. Approximately 70% of the Source Plasma (SP) used for PDMP manufacturing comes from United States (US). The hypothesis of the study is that US donation frequency does not impair donor self-reported functional health and well-being.

STUDY DESIGN AND METHODS

A total of 5608 SP donors from 14 US SP centers were enrolled in a cross-sectional study to assess self-reported health related quality of life (HRQoL) and well-being. By sex, donors were assigned to one of four groups, according to their frequency of SP donation in the 12 months before enrollment. The SF-36v2® Health Survey (SF-36v2) and a survey assessing the frequency of various health conditions that may be associated with impaired immune function over different time periods were used.

RESULTS

There were no statistically significant differences in SF-36v2 scores between any of the donor frequency groups, compared with new donors after controlling for potential confounding and accounting for multiple comparisons among males and females. Cough, cold, occasional fatigue, and sore throat were the most reported health conditions or symptoms, but there was no clear difference among sex or frequency groups.

DISCUSSION

The self-reported data in this study support the hypothesis that compensated donations at US FDA permitted frequencies and volumes are consistent with maintaining donor health. Compared with the general population, SP donors have comparable or better health than the general population.

Associations between Antiepileptic Use and Hypogammaglobulinaemia: Findings from a Population-Based Case-Control Study Using Data Linkage

BACKGROUND AND OBJECTIVES

Increased mortality in epilepsy due to infections (other than pneumonia) has been demonstrated. Small case series of people on antiepileptic drugs (AEDs) have described hypogammaglobulinaemia, which may predispose to infections. It is unclear whether hypogammaglobulinaemia is more frequent in people on AEDs, what AEDs it is associated with, or what clinical impact it has. In this population-based study, we aimed to determine whether AEDs were associated with hypogammaglobulinaemia, which AEDs were associated, and whether the associations may be causal.

METHODS

We conducted an unmatched case-control study using data linkage of routinely collected biochemistry, prescribing, and morbidity datasets in North-East Scotland from 2009-2021. Cases were participants with immunoglobulin levels less than the reference range. Controls were those with normal/high immunoglobulin levels. Logistic regression was used to investigate associations between AED exposure and any hypogammaglobulinaemia, adjusting for age, sex, and comorbidity. We also analysed low IgA, IgM, and IgG separately. We analysed "any AED" exposure and common individual drugs separately. Cumulative exposure data were used to determine whether an exposure-response relationship was present.

RESULTS

18,666 cases and 127,157 controls were identified. Use of any AED was associated with increased risk of hypogammaglobulinaemia (adjusted odds ratio [aOR] 1.20 [95% CI: 1.15-1.25]). Phenytoin use was strongly associated with low IgA (aOR 5.90 [95% CI: 3.04, 10.43]). Carbamazepine and lamotrigine were also associated with low IgA. Apart from topiramate, which was associated with a non-significant decrease in odds of hypogammaglobulinaemia, there was a consistent increase in odds of hypogammaglobulinaemia across most AEDs studied. Panhypogammaglobulinaemia was associated with any AED use, carbamazepine, lamotrigine, gabapentin, and multiple AED use. There was evidence of an exposure-response relationship between any AED use and any hypogammaglobulinaemia, low IgA, and low IgG. Carbamazepine and probably lamotrigine also had an exposure-response relationship with any hypogammaglobulinaemia.

DISCUSSION

AEDs may increase hypogammaglobulinaemia risk. Specific classes of immunoglobulins are differentially affected, and the exposure-response analysis suggests this may be causal. Further work should investigate the clinical impact of these findings. Clinicians should check immunoglobulin levels if unusual or recurrent infections occur in patients treated with AEDs.

Circulation of Respiratory Viruses in the City: Towards an Agent-Based Ecosystem model

Mathematical models play an important role in management of outbreaks of acute respiratory infections (ARI). While such models are generally used to study the spread of a solitary virus, in reality multiple viruses co-circulate in the population. These viruses have been studied in detail, including the course of infection and immune defense mechanisms. We developed an agent-based model, called ABM-ARI, assimilating heterogeneous data and theoretical knowledge into a biologically motivated system, that allows to reproduce the seasonal patterns of ARI incidence and simulate interventions. ABM-ARI uses city-specific data to create a synthetic population and to construct realistic contact networks in different activity settings. Characteristics of infection, immune protection and non-specific resistance were varied between individuals to account for the population heterogeneity. For the calibration, we minimised the normalised mean absolute error between simulated and observed epidemic curves. ABM-ARI was built based on the quantitative assessment of features of predominant respiratory viruses and epidemiological characteristics of the population. It provides a good fit to the observed epidemic curves for different age groups and viruses. We also simulated one-week school closures when student absences were at or above 10%, 20% or 30% and found that only 10% and 20% thresholds resulted in a reduction of the incidence. ABM-ARI has a great potential in tackling the challenge of emerging infections by simulating and evaluating the effectiveness of various interventions.

The association between hypogammaglobulinemia severity and infection risk in rituximab-treated patients with childhood-onset idiopathic nephrotic syndrome

BACKGROUND

Hypogammaglobulinemia is a major adverse effect from rituximab. However, the association between rituximab-induced hypogammaglobulinemia and infection frequency is unknown.

METHODS

Patients who received rituximab for complicated nephrotic syndrome between February 2006 and October 2020 were enrolled in this retrospective observational study. Infections requiring antibacterial or antiviral agents or hospitalization were identified, and the characteristics of infections were compared according to infection type.

RESULTS

One hundred and forty patients were enrolled. Fifty infection events were detected in 36 patients, 45 infection events in 32 patients required hospitalization, and 1 severe infection event required intensive care unit admission. In eight patients who developed severe hypogammaglobulinemia (serum IgG level < 200 mg/dL) for more than 1 year after rituximab treatment, eight infections occurred in six patients; six of these infections did not occur during the period of severe hypogammaglobulinemia. Febrile neutropenia accounted for 54.2% (13/24) of all infections among the patients with hypogammaglobulinemia. The incidence of infections was 0.028 (95% confidence interval = 0.017-0.448), 0.071 (95% [CI] = 0.041-0.114), and 0.096 (95% [CI] = 0.019-0.282) patient-years in patients with normal serum IgG levels and those with mild and severe hypogammaglobulinemia, respectively. Immunoglobulin replacement therapy was not administered to any patients except for the treatment of infection.

CONCLUSIONS

Our results showed no statistically significant association between hypogammaglobulinemia severity and infection rate. In addition, the frequency of infection was relatively low even in patients with severe hypogammaglobulinemia, suggesting that immunoglobulin replacement therapy may not be necessary for rituximab-treated patients with severe hypogammaglobulinemia. A higher resolution version of the Graphical abstract is available as Supplementary information.

The effect of cladribine on immunoglobulin levels compared to B cell targeting therapies in multiple sclerosis

Background

Cladribine is a useful therapeutic option in RRMS with moderate to high disease activity. Its oral formulation and tolerability make it a useful alternative to infusion therapies. Cladribine is known to deplete CD19⁺ B lymphocytes, but its effect on immunoglobulin subsets is unclear.

Objective

To identify whether cladribine therapy in pwMS reduces immunoglobulin subset levels as a surrogate marker of infection risk.

Methods

A 'real-world' retrospective analysis of 341 pwMS presenting to a single tertiary centre between March 2017 and July 2021. Differences in immunoglobulin levels between cladribine, other disease-modifying therapies and no active treatment were assessed using a univariate ANOVA.

Results

Three hundred and forty-one patients had immunoglobulin levels assessed, with 29 patients treated with cladribine. The mean IgG, IgM and IgA levels on cladribine therapy were 10.44 ± 0.40, 0.99 ± 0.09 and 2.04 ± 0.18 g/L respectively. These were not significantly different from patients not on active treatment. There was a statistically significant reduction in IgG and IgM levels for patients treated with ocrelizumab (9.37 ± 0.19 and 0.68 ± 0.04 g/L) and natalizumab (8.72 ± 0.53 and 0.69 ± 0.12 g/L) compared to patients not on treatment.

Conclusion

Cladribine therapy for RRMS was not associated with immunoglobulin subset deficiencies. This is contrasted to ocrelizumab and natalizumab which demonstrate significant reductions in both IgG and IgM levels.

Efgartigimod alfa for the treatment of primary immune thrombocytopenia

Primary immune thrombocytopenia (ITP) is an acquired autoimmune disorder characterized by isolated thrombocytopenia. Most patients with ITP have antiplatelet antibodies of the immunoglobulin G (IgG) subtype which through interaction with platelet and megakaryocyte glycoproteins result in increased platelet destruction and inhibition of platelet production. There are a variety of therapeutic options available for the treatment of ITP including corticosteroids, IVIgG, TPO-RA, rituximab, fostamatinib, and splenectomy. Long-term remissions with any of these therapies can vary widely and patients may require additional therapy. The neonatal Fc receptor (FcRn) plays a pivotal role in IgG and albumin physiology through recycling pathways. Efgartigimod is a human IgG1-derived fragment that has been modified by ABDEG technology to increase its affinity for FcRn at both physiologic and acidic pH. The binding of efgartigimod to FcRn blocks the interaction of IgG with FcRn facilitating increased lysosomal degradation of IgG and decreasing total IgG levels. Based on the mechanism of action and the known pathophysiology of ITP as well as the efficacy of other therapies such as intravenous immunoglobulin (IVIG), the use of efgartigimod in patients with ITP is attractive. This article will briefly discuss the pathophysiology of ITP, current treatments, and the data available on efgartigimod in ITP.

Advancing Biologic Therapy for Refractory Autoimmune Hepatitis

Biologic agents may satisfy an unmet clinical need for treatment of refractory autoimmune hepatitis. The goals of this review are to present the types and results of biologic therapy for refractory autoimmune hepatitis, indicate opportunities to improve and expand biologic treatment, and encourage comparative clinical trials. English abstracts were identified in PubMed by multiple search terms. Full-length articles were selected for review, and secondary and tertiary bibliographies were developed. Rituximab (monoclonal antibodies against CD20 on B cells), infliximab (monoclonal antibodies against tumor necrosis factor-alpha), low-dose recombinant interleukin 2 (regulatory T cell promoter), and belimumab (monoclonal antibodies against B cell activating factor) have induced laboratory improvement in small cohorts with refractory autoimmune hepatitis. Ianalumab (monoclonal antibodies against the receptor for B cell activating factor) is in clinical trial. These agents target critical pathogenic pathways, but they may also have serious side effects. Blockade of the B cell activating factor or its receptors may disrupt pivotal B and T cell responses, and recombinant interleukin 2 complexed with certain interleukin 2 antibodies may selectively expand the regulatory T cell population. A proliferation-inducing ligand that enhances T cell proliferation and survival is an unevaluated, potentially pivotal, therapeutic target. Fully human antibodies, expanded target options, improved targeting precision, more effective delivery systems, and biosimilar agents promise to improve efficacy, safety, and accessibility. In conclusion, biologic agents target key pathogenic pathways in autoimmune hepatitis, and early experiences in refractory disease encourage clarification of the preferred target, rigorous clinical trial, and comparative evaluations.

Hypogammaglobulinemia in pediatric kidney transplant recipients

Infections remain the most common cause of hospitalization after kidney transplantation, contributing to significant post-transplant morbidity and mortality. There is a growing body of literature that suggests that immunoglobulins may have a significant protective role against post-transplant infections, although the literature remains sparse, inconsistent, and not well publicized among pediatric nephrologists. Of great concern are data indicating a high prevalence of immunoglobulin abnormalities following transplantation and a possible link between these abnormalities and poorer outcomes. Our educational review focuses on the epidemiology and risk factors for the development of immunoglobulin abnormalities after kidney transplantation, the outcomes in patients with low immunoglobulin levels, and studies evaluating possible interventions to correct these immunoglobulin abnormalities.

Rituximab-Induced Hypogammaglobulinemia and Risk of Infection in Neuromyelitis Optica Spectrum Disorders

Background and Objectives

To investigate the frequency and predictors of hypogammaglobulinemia during long-term rituximab (RTX) treatment in patients with neuromyelitis optica spectrum disorder (NMOSD) and its association with infections.

Methods

We retrospectively reviewed the data of patients with NMOSD who received RTX through the maintenance regimen based on memory B-cell detection for at least 1 year from 2006 to 2021 at an institutional referral center for NMOSD.

Results

A total of 169 patients received a median of 10 courses (range 1–27) of RTX reinfusion after induction over a median of 8 (range, 1–15) years. Their mean serum immunoglobulin (Ig)G level began to decline significantly after 2 years of treatment, steadily declined at a rate of 2%–8% per year for the following 8 years, and then plateaued after 10 years. The proportion of patients with hypo-IgG (<6 g/L) increased from 1.2% after 1 year of treatment to 41% after 14 years of treatment. While being treated with RTX, 58 (34%) patients had 114 infections, of whom 14 (8%) patients had 15 severe infections. Multivariable logistic regression analyses identified duration of RTX treatment in years (odds ratio [OR] 1.234, 95% confidence interval [CI] 1.015–1.502), mean annual RTX dose (OR 0.063, 95% CI 0.009–0.434), history of mitoxantrone (OR 3.318, 95% CI 1.109–9.93), hypo-IgG at baseline (OR 40.552, 95% CI 3.024–543.786), and body mass index >25 kg/m² (OR 4.798, 95% CI 1.468–15.678) as independent predictors of hypo-IgG. The risk of infection during RTX treatment was independently associated with high Expanded Disability Status Scale scores (OR 1.427, 95% CI 1.2–1.697) and relapses during RTX treatment (OR 1.665, 95% CI 1.112–2.492), but not with hypogammaglobulinemia.

Discussion

Over 14 years of long-term RTX treatment, IgG levels gradually decreased, and the frequency of hypo-IgG increased to 41% of the patients. Patients with prolonged memory B-cell depletion after RTX, previous mitoxantrone history, hypo-IgG at baseline, or obesity were at risk of developing RTX-induced hypogammaglobulinemia. Nevertheless, infection rates remained low during treatment, and reduced immunoglobulin levels were not associated with an increased incidence of infections.

Immunodeficiency in patients with thymoma-associated myasthenia gravis

Thymoma with immunodeficiency is sometimes accompanied by myasthenia gravis (MG), but the clinical characteristics have not been elucidated. This study aimed to characterize its clinical and immunological features. Of the 132 thymoma-associated MG patients, 9 patients presented with immunodeficiency. All suffered from severe pneumonia, and most had invasive thymoma and autoimmune disorders. DRB1*08:03 and DQB1*06:01 alleles were frequently detected. Compared to group without immunodeficiency, they showed no significant differences in the severity of MG, significantly lower IgG concentrations and higher mortality rate. Thymoma-associated MG with immunodeficiency is a distinct subset requiring special attention to prevent infection during the follow-up period.

Targeting neonatal Fc receptor: potential clinical applications in pregnancy

The neonatal Fc receptor (FcRn) plays an important role in the transfer of the immunoglobulin G isotype (IgG) from the mother to the fetus. FcRn expressed on endothelial cells also binds to IgG and albumin, regulating the circulating half-lives of these proteins. Alloimmune and autoimmune IgG antibodies have been implicated in various perinatal immune-mediated diseases. FcRn-mediated placental transfer of pathogenic antibodies can result in cell and tissue injury in the fetus and neonate, with devastating outcomes. Thus, blockade of FcRn may be an effective treatment strategy in managing these conditions and could additionally reduce the concentration of pathogenic antibodies in the maternal circulation by preventing IgG recycling. In this review, we discuss the biology of FcRn, the rationale and considerations for development of FcRn-blocking agents, and their potential clinical applications in various perinatal immune-mediated diseases. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Isolated IgG2 deficiency is an independent risk factor for exacerbations in bronchiectasis

BACKGROUND

Immunoglobulin G (IgG) subclass 2 deficiency is the most frequent IgG subclass deficiency identified in patients with bronchiectasis, but its clinical significance is not known.

AIM

To analyse if bronchiectasis patients with isolated IgG2 deficiency at risk of recurrent exacerbations and/or hospitalization? Do patients with IgG2 deficiency have worse disease progression?

DESIGN AND METHODS

This is a retrospective study (2015-20) exploring independent risk factors for recurrent exacerbations (3 or more per year) and/or hospitalization with bronchiectasis exacerbations using multivariable models using binary logistic regression. There was no patient with IgG deficiency, IgG 1, 3 or 4 deficiency, or IgA or IgM deficiency included. In this model, the authors included: serum IgG2 level; lung function; body mass index; MRC breathlessness scale; age; sex; number of bronchiectatic lobes; bacterial colonization; comorbidities; and the use of long-term immunosuppressant drugs or antibiotics for more than 28 days. Analysing 2-year longitudinal data, one-way ANOVA and Mann-Whitney U-test were used to compare bronchiectasis severity between patients with different IgG2 levels.

RESULTS

Serum IgG2 levels (<2.68 g/l, 2.68-3.53 g/l and 3.54-4.45 g/l); hospital admission in the preceding 2 years; bacterial colonization with potentially pathogenic organisms and asthma were independent predictors for three or more bronchiectasis exacerbations. Those with low IgG2 levels (<2.68 g/l and 2.68-3.53 g/l), had worsening progression of their bronchiectasis, using the Bronchiectasis Severity Index, over 1 year compared with those who were IgG2 replete (>4.45 g/l) (P = 0.003, 0.013).

CONCLUSION

Reduced IgG2 levels were an independent predictor for bronchiectasis exacerbations and have increased disease progression.

Polysaccharides from Spores of Cordyceps cicadae Protect against Cyclophosphamide-Induced Immunosuppression and Oxidative Stress in Mice

This study investigated the purification, preliminary structure and in vivo immunomodulatory activities of polysaccharides from the spores of Cordyceps cicadae (CCSP). The crude CCSP was purified by diethylaminoethyl (DEAE)-cellulose and Sephadex G-100 chromatography, affording CCSP-1, CCSP-2 and CCSP-3 with molecular weights of 1.79 × 10⁶, 5.74 × 10⁴ and 7.93 × 10³ Da, respectively. CCSP-2 consisted of mannose and glucose, while CCSP-1 and CCSP-3 are composed of three and four monosaccharides with different molar ratios, respectively. CCSP-2 exhibited its ameliorative effects in cyclophosphamide-induced immunosuppressed mice through significantly increasing spleen and thymus indices, enhancing macrophage phagocytic activity, stimulating splenocyte proliferation, improving natural killer (NK) cytotoxicity, improving bone marrow suppression, regulating the secretion of cytokines and immunoglobulins, and modulating antioxidant enzyme system. These results indicate that CCSP-2 might be exploited as a promising natural immunomodulator.

Maintained partial protection against Streptococcus pneumoniae despite B-cell depletion in mice vaccinated with a pneumococcal glycoconjugate vaccine

OBJECTIVES

Anti-CD20 monoclonal antibody therapy rapidly depletes > 95% of CD20⁺ B cells from the circulation. B-cell depletion is an effective treatment for autoimmune disease and B-cell malignancies but also increases the risk of respiratory tract infections. This effect on adaptive immunity could be countered by vaccination. We have used mouse models to investigate the effects of B-cell depletion on pneumococcal vaccination, including protection against infection and timing of vaccination in relation to B-cell depletion.

METHODS

C57BL/6 female mice were B-cell depleted using anti-CD20 antibody and immunized with two doses of Prevnar-13 vaccine either before or after anti-CD20 treatment. B-cell repertoire and Streptococcus pneumoniae-specific IgG levels were measured using whole-cell ELISA and flow cytometry antibody-binding assay. Protection induced by vaccination was assessed by challenging the mice using a S. pneumoniae pneumonia model.

RESULTS

Antibody responses to S. pneumoniae were largely preserved in mice B-cell depleted after vaccination resulting in full protection against pneumococcal infections. In contrast, mice vaccinated with Prevnar-13 while B cells were depleted (with > 90% reduction in B-cell numbers) had decreased circulating anti-S. pneumoniae IgG and IgM levels (measured using ELISA and flow cytometry antibody binding assays). However, some antibody responses were maintained, and, although vaccine-induced protection against S. pneumoniae infection was impaired, septicaemia was still prevented in 50% of challenged mice.

CONCLUSIONS

This study showed that although vaccine efficacy during periods of profound B-cell depletion was impaired some protective efficacy was preserved, suggesting that vaccination remains beneficial.

Effectiveness of Belimumab After Rituximab in Systemic Lupus Erythematosus : A Randomized Controlled Trial

BACKGROUND

B-cell depletion with rituximab is commonly used for patients with systemic lupus erythematosus (SLE) that is refractory to conventional therapy, but it yields variable responses. We hypothesized that high B-cell activating factor (BAFF) levels after rituximab can cause disease flares, thereby limiting its effectiveness.

OBJECTIVE

To obtain preliminary evidence for efficacy of the anti-BAFF therapeutic belimumab after rituximab in SLE.

DESIGN

Phase 2, randomized, double-blind (patients, assessors, researchers, care providers), placebo-controlled, parallel-group, superiority trial. (ISRCTN: 47873003).

SETTING

England.

PARTICIPANTS

Fifty-two patients who had SLE that was refractory to conventional treatment and whose physicians had recommended rituximab therapy were recruited between 2 February 2017 and 28 March 2019.

INTERVENTION

Participants were treated with rituximab and 4 to 8 weeks later were randomly assigned (1:1) to receive intravenous belimumab or placebo for 52 weeks.

MEASUREMENTS

The prespecified primary end point was serum IgG anti-double-stranded DNA (anti-dsDNA) antibody levels at 52 weeks. Secondary outcomes included incidence of disease flares and adverse events.

RESULTS

At 52 weeks, IgG anti-dsDNA antibody levels were lower in patients treated with belimumab compared with placebo (geometric mean, 47 [95% CI, 25 to 88] vs. 103 [CI, 49 to 213] IU/mL; 70% greater reduction from baseline [CI, 46% to 84%]; P < 0.001). Belimumab reduced risk for severe flare (BILAG-2004 grade A) compared with placebo (hazard ratio, 0.27 [CI, 0.07 to 0.98]; log-rank P = 0.033), with 10 severe flares in the placebo group and 3 in the belimumab group. Belimumab did not increase incidence of serious adverse events. Belimumab significantly suppressed B-cell repopulation compared with placebo (geometric mean, 0.012 [CI, 0.006 to 0.014] vs. 0.037 [CI, 0.021 to 0.081] × 10⁹/L) at 52 weeks in a subset of patients (n = 25) with available data.

LIMITATIONS

Small sample size; biomarker primary end point.

CONCLUSION

Belimumab after rituximab significantly reduced serum IgG anti-dsDNA antibody levels and reduced risk for severe flare in patients with SLE that was refractory to conventional therapy. The results suggest that this combination could be developed as a therapeutic strategy.

PRIMARY FUNDING SOURCE

Versus Arthritis.

Safety, efficacy, and tolerability of efgartigimod in patients with generalised myasthenia gravis (ADAPT): a multicentre, randomised, placebo-controlled, phase 3 trial

BACKGROUND

There is an unmet need for treatment options for generalised myasthenia gravis that are effective, targeted, well tolerated, and can be used in a broad population of patients. We aimed to assess the safety and efficacy of efgartigimod (ARGX-113), a human IgG1 antibody Fc fragment engineered to reduce pathogenic IgG autoantibody levels, in patients with generalised myasthenia gravis.

METHODS

ADAPT was a randomised, double-blind, placebo-controlled, phase 3 trial done at 56 neuromuscular academic and community centres in 15 countries in North America, Europe, and Japan. Patients aged at least 18 years with generalised myasthenia gravis were eligible to participate in the study, regardless of anti-acetylcholine receptor antibody status, if they had a Myasthenia Gravis Activities of Daily Living (MG-ADL) score of at least 5 (>50% non-ocular), and were on a stable dose of at least one treatment for generalised myasthenia gravis. Patients were randomly assigned by interactive response technology (1:1) to efgartigimod (10 mg/kg) or matching placebo, administered as four infusions per cycle (one infusion per week), repeated as needed depending on clinical response no sooner than 8 weeks after initiation of the previous cycle. Patients, investigators, and clinical site staff were all masked to treatment allocation. The primary endpoint was proportion of acetylcholine receptor antibody-positive patients who were MG-ADL responders (≥2-point MG-ADL improvement sustained for ≥4 weeks) in the first treatment cycle. The primary analysis was done in the modified intention-to-treat population of all acetylcholine receptor antibody-positive patients who had a valid baseline MG-ADL assessment and at least one post-baseline MG-ADL assessment. The safety analysis included all randomly assigned patients who received at least one dose or part dose of efgartigimod or placebo. This trial is registered at ClinicalTrials.gov (NCT03669588); an open-label extension is ongoing (ADAPT+, NCT03770403).

FINDINGS

Between Sept 5, 2018, and Nov 26, 2019, 167 patients (84 in the efgartigimod group and 83 in the placebo group) were enrolled, randomly assigned, and treated. 129 (77%) were acetylcholine receptor antibody-positive. Of these patients, more of those in the efgartigimod group were MG-ADL responders (44 [68%] of 65) in cycle 1 than in the placebo group (19 [30%] of 64), with an odds ratio of 4·95 (95% CI 2·21-11·53, p<0·0001). 65 (77%) of 84 patients in the efgartigimod group and 70 (84%) of 83 in the placebo group had treatment-emergent adverse events, with the most frequent being headache (efgartigimod 24 [29%] vs placebo 23 [28%]) and nasopharyngitis (efgartigimod ten [12%] vs placebo 15 [18%]). Four (5%) efgartigimod-treated patients and seven (8%) patients in the placebo group had a serious adverse event. Three patients in each treatment group (4%) discontinued treatment during the study. There were no deaths.

INTERPRETATION

Efgartigimod was well tolerated and efficacious in patients with generalised myasthenia gravis. The individualised dosing based on clinical response was a unique feature of ADAPT, and translation to clinical practice with longer term safety and efficacy data will be further informed by the ongoing open-label extension.

FUNDING

argenx.

Preoperative lymphopaenia, mortality, and morbidity after elective surgery: systematic review and meta-analysis

BACKGROUND

In the general adult population, lymphopaenia is associated with an increased risk for hospitalisation with infection and infection-related death. The quality of evidence and strength of association between perioperative lymphopaenia across different surgical procedures and mortality/morbidity has not been examined by systematic review or meta-analysis.

METHODS

We searched MEDLINE, Embase, Web of Science, Google Scholar, and Cochrane databases from their inception to June 29, 2020 for observational studies reporting lymphocyte count and in-hospital mortality rate in adults. We defined preoperative lymphopaenia as a lymphocyte count 1.0-1.5×109 L-1. Meta-analysis was performed using either fixed or random effects models. Quality was assessed using the Newcastle-Ottawa Scale. The I2 index was used to quantify heterogeneity. The primary outcome was in-hospital mortality rate and mortality rate at 30 days.

RESULTS

Eight studies met the inclusion criteria for meta-analysis, comprising 4811 patients (age range, 46-91 yr; female, 20-79%). These studies examined preoperative lymphocyte count exclusively. Studies were of moderate to high quality overall, ranking >7 using the Newcastle-Ottawa Scale. Preoperative lymphopaenia was associated with a threefold increase in mortality rate (risk ratio [RR]=3.22; 95% confidence interval [CI], 2.19-4.72; P<0.01, I2=0%) and more frequent major postoperative complications (RR=1.33; 95% CI, 1.21-1.45; P<0.01, I2=6%), including cardiovascular morbidity (RR=1.77; 95% CI, 1.45-2.15; P<0.01, I2=0%), infections (RR=1.45; 95% CI, 1.19-1.76; P<0.01, I2=0%), and acute renal dysfunction (RR=2.66; 95% CI, 1.49-4.77; P<0.01, I2=1%).

CONCLUSION

Preoperative lymphopaenia is associated with death and complications more frequently, independent of the type of surgery.

PROSPERO REGISTRY NUMBER

CRD42020190702.

Hypogammaglobulinemia after rituximab for rheumatoid arthritis is not rare and is related with good response: 13 years real-life experience

OBJECTIVES

Rituximab (RTX) use in the treatment of RA can be complicated by decrease in IgG, IgM or IgA levels (hypogammaglobulinemia-HGG). The aim of this study was to define the frequency of HGG in RA patients treated with RTX and to identify associations between its occurrence and patients' characteristics, disease outcomes and serious infections rate.

METHODS

RA patients treated with RTX in two rheumatology centers from January 2007 to January 2020 were retrospectively examined. Demographical, clinical and laboratory parameters were recorded at baseline and at last visit.

RESULTS

Eighty-three patients (84.3% females) with a mean age of 63.2 years were enrolled. They had baseline DAS28(CRP) of 5.2  (1.1) and received a median (range) of 8 (2-20) RTX cycles. A total of 43.4%, 24.1% and 31.3% developed 'any HGG', 'low IgG' and 'low IgM', respectively. Lower baseline IgG and IgM levels were predictors of 'low IgG' and 'low IgM' occurrence, respectively. Patients who developed 'low IgM' exhibited lower DAS28(CRP) and increased rates of remission and low disease activity compared with those with normal IgM levels. Patients who maintained normal IgG were receiving methotrexate more frequently. No differences were observed in serious infections rate among subgroups.

CONCLUSION

HGG occurred in 43% of RTX-treated patients. Patients who developed low IgG or low IgM had lower baseline levels than those who did not. Concomitant DMARD and corticosteroid therapy was not associated with HGG. Low IgM, but not low IgG, development was associated with better disease outcomes. HGG was not associated with an increased incidence of serious infections.

Development and Validation of a Clinical Predictive Model for Bacterial Infection in Hepatitis B Virus-Related Acute-on-Chronic Liver Failure

INTRODUCTION

Bacterial infection is one of the most frequent complications in hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF), which leads to high mortality. However, a predictive model for bacterial infection in HBV-ACLF has not been well established. This study aimed to establish and validate a predictive model for bacterial infection in two independent patient cohorts.

METHODS

Admission data from a prospective cohort of patients with HBV-ACLF without bacterial infection on admission was used for derivation. Bacterial infection development from day 3 to 7 of admission was captured. Independent predictors of bacterial infection development on multivariate logistic regression were used to develop the predictive model. External validation was performed on a separate retrospective cohort.

RESULTS

A total of 377 patients were enrolled into the derivation cohort, including 88 patients (23.3%) who developed bacterial infection from day 3 to 7 of admission. On multivariate regression analysis, admission serum globulin (OR 0.862, 95% CI 0.822-0.904; P < 0.001), interleukin-6 (OR 1.023, 95% CI 1.006-1.040; P = 0.009), and C-reactive protein (OR 1.123, 95% CI 1.081-1.166; P < 0.001) levels were independent predictors for the bacterial infection development, which were adopted as parameters of the predictive model (GIC). In the derivation cohort, the area under the curve (AUC) of GIC was 0.861 (95% CI 0.821-0.902). A total of 230 patients were enrolled into the validation cohort, including 57 patients (24.8%) who developed bacterial infection from day 3 to 7 of admission, and the AUC of GIC was 0.836 (95% CI 0.782-0.881). The Hosmer-Lemeshow test showed a good calibration performance of the predictive model in the two cohorts (P = 0.199, P = 0.746). Decision curve analysis confirmed the clinical utility of the predictive model.

CONCLUSION

GIC was established and validated for the prediction of bacterial infection development in HBV-ACLF, which may provide a potential auxiliary solution for the primary complication of HBV-ACLF.

Bacteremia with ESBL-producing Enterobacterales is associated with IgG antibodies reacting with CTX-M-15 and/or CTX-M-27

OBJECTIVES

The adaptive humoral immune response following clinical infection with extended spectrum beta-lactamase (ESBL)-producing Enterobacterales (EPE) has not been thoroughly investigated. The aim of this study was to investigate the presence of anti-CTX-M-15 and/or anti-CTX-M-27 IgG antibodies in bacteremia patients diagnosed with EPE compared to a control group consisting of patients suffering from bacteremia with third generation cephalosporin-susceptible Escherichia coli (3GCSE).

METHODS

Patientswith EPE (n = 59) or 3GCSE (n = 42) bacteremia were recruited in this case control study in the Skåne County (South of Sweden). Sera were collected 1-26 months after bacteremia. Enzyme-linked immunosorbent assay (ELISA) was used for detection of specific IgG antibodies directed against recombinant beta-lactamases CTX-M-15 and CTX-M-27. The beta-lactamase resistance genes of the corresponding EPE blood isolates were determined by DNA sequencing.

RESULTS

The majority (n = 47; 80 %) of the 59 EPE blood isolates carried bla_CTX-M-15 or bla_CTX-M-27 genes. IgG antibodies reacting to the corresponding CTX-M enzyme was seen in 28 % (13/47) of patients suffering from EPE-bacteremia, while antibodies were detected in only 9.5 % (4/42) of patients with 3GCSE (p = 0.03). Patients with EPE had a statistically significantly higher median Charlson comorbidity index and prevalence of renal disease (p = 0.01), compared to the 3GCSE control group.

CONCLUSION

This study implies that EPE bacteremia can trigger production of IgG antibodies targeting ESBL. Further investigations are required to determine the functional role of anti-ESBL antibodies against EPE bacteremia.

A comparison for the effects of raw, smoked, and smoked and brined areca nut extracts on the immune and inflammatory responses in the Kunming mice

Chewing of areca nuts is quite popular in various regions worldwide. Previous studies have demonstrated the pharmacological and toxicological effects of fresh areca nuts. However, processed areca nuts, which are popular in the Hunan province of China, have not been extensively studied for its biological effect. This study aimed at investigating the impact of the acrea nut extracts (ANE) prepared from the raw material, the semi-product, and the final product on the immune system and inflammation-related markers in the Kunming mice. The mice were assigned to seven different groups and administered different ANE at two concentrations (1X and 5X) for four weeks. Total body weight gain and organ coefficient of the liver, spleen, and kidney, as well as the immune system and inflammation-related markers were evaluated. The results revealed that processed areca nuts have a much milder effect on the mice immune system and some inflammatory markers than fresh areca nut in the Kunming mice. PRACTICAL APPLICATIONS: Chewing various forms of areca nuts is popular in China, Southeast Asia, and other regions. People from Hunan, China prefer to chew a processed areca nut, which has rarely been studied. This manuscript explores the effects of three kinds of areca nut extracts on the immune system- and inflammation-related indicators in Kunming mice. The obtained results revealed that processed areca nuts had significantly milder effects than the raw nut/nut extract, particularly on the body weight, immune responses, and inflammatory markers. The results of the present study provide some new directions for the areca nut industry and raise public awareness for the undesirable effects of areca nuts.

Oral management of a patient with down syndrome and agammaglobulinemia: a case report

Background

Down syndrome is characterized by a variety of dysmorphic features and congenital malformations, such as congenital heart disease, gastrointestinal disease, and other conditions like leukemia and autoimmune disorders. Patients with Down syndrome are highly prone to respiratory tract infections, which might be fatal to them. However, there are only few available data on patients diagnosed with Down syndrome and agammaglobulinemia. In this report, we describe a case of successful prevention of post-dental treatment complications (e.g., pneumonia and other bacterial infections) in a patient with Down syndrome and agammaglobulinemia.

Case presentation

A 43-year-old man with Down syndrome, untreated agammaglobulinemia, and a history of recurrent pneumonia, was referred to our clinic for tooth mobility. To reduce the risk of post-operative infections, gammaglobulin treatment and prophylactic administration of antibiotics was scheduled before the dental procedure. Furthermore, the dental treatment, which included a filling and extractions, was conducted under general anesthesia and with the supervision of a hematologist. The dental procedures were successfully performed without any post-operative infection, and the patient is undergoing follow-up care.

Conclusions

The purpose of this case report was to recommend a close liaison between physicians and dentists who may encounter a similar case, and to emphasize the importance of improving oral health of immunodeficient patients to prevent infections caused by oral microbial flora.

Phase 2 study of efgartigimod, a novel FcRn antagonist, in adult patients with primary immune thrombocytopenia

Primary immune thrombocytopenia (ITP) is an acquired autoimmune bleeding disorder, characterized by a low platelet count (<100 × 10⁹/L) in the absence of other causes associated with thrombocytopenia. In most patients, IgG autoantibodies directed against platelet receptors can be detected. They accelerate platelet clearance and destruction, inhibit platelet production, and impair platelet function, resulting in increased risk of bleeding and impaired quality of life. Efgartigimod is a human IgG1 antibody Fc‐fragment, a natural ligand of the neonatal Fc receptor (FcRn), engineered for increased affinity to FcRn, while preserving its characteristic pH‐dependent binding. Efgartigimod blocks FcRn, preventing IgG recycling, and causing targeted IgG degradation. In this Phase 2 study, 38 patients were randomized 1:1:1 to receive four weekly intravenous infusions of either placebo (N = 12) or efgartigimod at a dose of 5 mg/kg (N = 13) or 10 mg/kg (N = 13). This short treatment cycle of efgartigimod in patients with ITP, predominantly refractory to previous lines of therapy, was shown to be well tolerated, and demonstrated a favorable safety profile consistent with Phase 1 data. Efgartigimod induced a rapid reduction of total IgG levels (up to 63.7% mean change from baseline), which was associated with clinically relevant increases in platelet counts (46% patients on efgartigimod vs 25% on placebo achieved a platelet count of ≥50 × 10⁹/L on at least two occasions, and 38% vs 0% achieved ≥50 × 10⁹/L for at least 10 cumulative days), and a reduced proportion of patients with bleeding. Taken together, these data warrant further evaluation of FcRn antagonism as a novel therapeutic approach in ITP.

Benefit-Risk Assessment of Blinatumomab in the Treatment of Relapsed/Refractory B-Cell Precursor Acute Lymphoblastic Leukemia

Blinatumomab is the first-and-only Food and Drug Administration (FDA)-approved cluster of differentiation (CD) 19-directed CD3 bispecific T-cell engager (BiTE^®) immunotherapy. It is currently FDA approved for the treatment of adults and children with Philadelphia chromosome-positive (Ph+) and Philadelphia chromosome-negative (Ph-) relapsed/refractory (R/R) B-cell precursor acute lymphoblastic leukemia (ALL) and B-cell precursor ALL with minimal residual disease. Similarly, initial marketing authorization for blinatumomab in the European Union was granted for the treatment of adults with Ph- R/R B-cell precursor ALL. The benefits of treating R/R B-cell precursor ALL patients with blinatumomab include increased overall survival, more favorable hematologic remission and molecular response rates, and a lower incidence rate of selected adverse events when compared with standard-of-care chemotherapy. The key risks associated with blinatumomab treatment include cytokine release syndrome, neurotoxicity, and medication errors. Here, we review the benefits and risks of blinatumomab treatment and describe how these risks can be mitigated.

Alemtuzumab therapy changes immunoglobulin levels in peripheral blood and CSF

Objective

The use of alemtuzumab, a humanized monoclonal anti-CD52 antibody has changed the therapy of highly active relapsing-remitting MS (RRMS). Alemtuzumab infusion depletes most lymphocytes in peripheral blood, whereas differential recovery of immune cells, probably those with a less CNS-autoreactive phenotype, is supposed to underlie its long-lasting effects. To determine whether alemtuzumab significantly reduces immunoglobulin levels in blood and CSF of treated patients, we analyzed blood and CSF samples of 38 patients with MS treated with alemtuzumab regarding changes in immunoglobulin levels.

Methods

Blood and CSF samples of patients were collected at the beginning of alemtuzumab treatment and at 12, 24, and 36 months after the first administration of the drug. Specimens were analyzed regarding immunoglobulin concentrations in blood and CSF.

Results

We observed significant and dose-dependent reductions of immunoglobulin levels (IgG, IgM, and IgA) in serum and CSF 12 and 24 months following 2 courses of alemtuzumab. Patients with persistent or returning disease activity who were treated with a third course of alemtuzumab exhibited even further decrease in IgG levels compared with matched controls treated twice. Here, alemtuzumab-treated patients with IgG levels below the lower limits of normal were more susceptible to pneumonia, sinusitis, and otitis, whereas upper respiratory tract and urinary tract infections were not associated therewith.

Conclusions

Our results suggest to monitor IgG levels for safety reasons in patients treated with alemtuzumab—in particular when additional treatment courses are required—and to consider preventive action in critical cases.

Classification of evidence

This study provides Class IV evidence that for patients with RRMS alemtuzumab reduces immunoglobulin levels.

Ovotransferrin ameliorates the dysbiosis of immunomodulatory function and intestinal microbiota induced by cyclophosphamide

In this study, the regulative effects of ovotransferrin (OVT) on immunomodulatory function and intestinal microbial dysbiosis in a mouse model injected with cyclophosphamide (CP) were investigated. The immunomodulatory effect of OVT was determined by enzyme-linked immune sorbent assay (ELISA). Gut microbial composition was determined by high-throughput sequencing of the V3-V4 region of the 16S rDNA gene. The changes in the relative abundance of the dominant microbiota were analyzed at different taxonomic levels. The results showed that OVT alleviated the immune dysfunction caused by CP. OVT improved the spleen and thymus indices and enhanced the secretion of tumor necrosis factor alpha (TNF-α), interleukin-10 (IL-10), and immunoglobulin A (IgA). In addition, OVT increased the indexes of Shannon and Simpson, suggesting the enhancement of the diversity and richness of intestinal microflora. The relative abundance of Lachnospiraceae_NK4A136_group was also increased. However, the relative abundance of Helicobacter and Desulfovibrio was significantly decreased. These results indicated that OVT, a food-derived functional component, has effects on immune regulation in the organism and ameliorates the gut microbiota disorders induced by CP, which provides a potential therapeutic utilization of avian eggs by targeting the gut microbiome.

Determination of antibodies in everyday rheumatological practice

Antibody determination is routinely used in everyday rheumatological practice. Its result repeatedly determines the diagnosis or exclusion of a particular disease. Antibodies are immunoglobulins, i.e. some of the most important proteins in the immune system, and have specific properties that we should know. In addition, there are a number of factors that can affect their concentration, including drugs commonly used in the treatment of rheumatic diseases. There are definite indications, when the total concentrations of individual classes of immunoglobulins should be initially determined and it should be evaluated whether the patient produces them at all or their production is impaired. In some cases, we should evaluate the levels of specific antibodies along with the total protein concentration and the γ-globulin fraction, in which the antibodies are contained. The article presents information on the most common mistakes made when performing these tests.

The role of G-quadruplex structures of LIGS-generated aptamers R1.2 and R1.3 in IgM specific recognition

Exploiting a variant of SELEX called "Ligand-Guided Selection" (LI-GS), we recently identified two novel truncated G-rich aptamers, called R1.2 and R1.3, specific for membrane-bound IgM (mIgM), the hallmark of B cells. Herein, the conformational behaviour of these aptamers has been analysed by multiple biophysical methods. In order to investigate their functional secondary structures, these studies have been carried out in pseudo-physiological buffers mimicking different cellular environments. Both aptamers proved to be highly polymorphic, folding into stable, unimolecular G-quadruplex structures in K⁺-rich buffers. In turn, in buffered solutions containing Na⁺/Mg²⁺ ions, R1.2 and R1.3 formed mainly duplex structures. Remarkably, these aptamers were able to effectively bind mIgM on B-cell lymphoma exclusively in the presence of potassium ions. These findings demonstrate the key role of G-quadruplex folding in the molecular recognition and efficient binding of R1.2 and R1.3 to mIgM expressed in lymphoma and leukemia cells, providing a precious rational basis for the design of effective aptamer-based biosensors potentially useful for the detection of cancer-relevant biomarkers.

Hexaammineruthenium (II)/(III) as alternative redox-probe to Hexacyanoferrat (II)/(III) for stable impedimetric biosensing with gold electrodes

Gold electrodes have been used in a wide range of electrochemical biosensors because their functionalization process with thiols has been well described and, in general, they offer good chemical stability. However, one of the most commonly used redox-pairs in electrochemical impedance spectroscopy, Hexacyanoferrate (II)/(III), causes corrosion of the gold electrodes and consequently damages the surface modification. This leads to alterations of the sensing signals, and thus, renders the quantitative and sensitive detection of target molecules virtually impossible. To overcome this problem we introduced the in-situ generation of Hexaammineruthenium (II)/(III) as redox-pair during the impedimetric measurement by applying a DC-bias. This DC-bias was chosen in such a way that it supplied Hexaammineruthenium (II) in a suitable concentration at the electrode surface by reducing Hexaammineruthenium (III). We compared the stability of photolithographically fabricated thin-film and screen-printed gold electrodes in Hexacyanoferrate and Hexaammineruthenium solutions. Further, long-time characterization of the electrochemical properties with cyclic voltammetry and electrochemical impedance spectroscopy revealed that Hexaammineruthenium (II)/(III) was an excellent redox-pair for stable impedimetric measurements with gold electrodes. To demonstrate the suitability of Hexaammineruthenium for biosensing we applied it for the impedimetric detection of human-IgG. This biosensor exhibited a linear range from 11.3 ng/mL to 113 μg/mL, which is a suitable range for diagnostic applications.

Serotypes With Low Invasive Potential Are Associated With an Impaired Antibody Response in Invasive Pneumococcal Disease

Pneumococcal polysaccharide vaccines may elicit a hyporesponse under certain conditions. There is limited knowledge, however, on the type of specific antibody response in individuals with invasive pneumococcal disease (IPD). The aim of this study was to investigate the functional antibody response in patients with IPD caused by different serotypes. Pre-immune and convalescent sera from 40 patients (age 14–91 years) with IPD caused by serotypes with low (serotype 3, 19F, and 23F) and high (1, 4, 7F, and 14) invasive potential were investigated. For each patient, the homologous serotype-specific antibody concentration was determined. The functionality of induced antibodies post-IPD was evaluated in an opsonophagocytic assay (OPA). Undetectable or decreased pneumococcal killing in OPA following IPD, i.e., a nonfunctional antibody response, was observed in 24 of 40 patients (60%). Patients with nonfunctional antibody responses had lower serotype specific IgG antibody ratios post-IPD than patients with increased OPA titres. A nonfunctional antibody response was associated with low invasive serotypes (3, 19F, and 23F, p = 0.015). In conclusion, a nonfunctional antibody response may follow IPD, and was in our cohort associated to serotypes with low invasive potential. These findings need to be confirmed in a larger material.

Rituximab-induced hypogammaglobulinemia in patients with neuromyelitis optica spectrum disorders

Objective

To evaluate the long-term effects of rituximab (RTX) on total and specific immunoglobulins (Igs) in patients with neuromyelitis optica spectrum disorders (NMOSDs).

Methods

Total IgG, IgA, and IgM levels were evaluated in 15 patients with NMOSDs treated with RTX (median follow-up 70 months). Anti-aquaporin 4 (AQP4)-IgG titration was performed on samples from 9 positive patients. Anti-tetanus (TET), anti-varicella-zoster virus (VZV), and anti-Epstein–Barr virus nuclear antigen (EBNA) IgGs were also tested in patients with NMOSDs and in 6 healthy controls (HCs).

Results

RTX reduced total IgG by 0.42 g/L per year, IgA by 0.08 g/L per year, and IgM by 0.07 g/L per year. Hypogammaglobulinemia (hypo-IgG) (IgG < 7 g/L) developed in 11/15 patients. Severe hypo-IgG (IgG < 4 g/L) was found in 3/15 patients, of whom 2 patients developed serious infectious complications. In group analysis, anti-AQP4 IgG titers were reduced by RTX over time, and a significant correlation between anti-AQP4 IgG titers and total IgG levels was found. The effects of RTX were observed on pathogen-specific IgGs as well. In particular, the levels of anti-TET IgG in patients were significantly lower than those in HCs. The half-life of anti-TET IgG was reduced by about 50% in patients compared with the general population.

Conclusions

Long-term RTX treatment is associated with the risk of hypo-Ig and reduction of anti-TET protection in patients with NMOSDs. Results obtained in this study suggest the importance of monitoring total and specific Ig levels before and during treatment with anti-CD20 drugs to prevent hypo-Ig–related complications and to optimize clinical management.

Neonatal Fc receptor antagonist efgartigimod safely and sustainably reduces IgGs in humans

BACKGROUND

Intravenous Ig (IVIg), plasma exchange, and immunoadsorption are frequently used in the management of severe autoimmune diseases mediated by pathogenic IgG autoantibodies. These approaches modulating IgG levels can, however, be associated with some severe adverse reactions and a substantial burden to patients. Targeting the neonatal Fc receptor (FcRn) presents an innovative and potentially more effective, safer, and more convenient alternative for clearing pathogenic IgGs.

METHODS

A randomized, double-blind, placebo-controlled first-in-human study was conducted in 62 healthy volunteers to explore single and multiple ascending intravenous doses of the FcRn antagonist efgartigimod. The study objectives were to assess safety, tolerability, pharmacokinetics, pharmacodynamics, and immunogenicity. The findings of this study were compared with the pharmacodynamics profile elicited by efgartigimod in cynomolgus monkeys.

RESULTS

Efgartigimod treatment resulted in a rapid and specific clearance of serum IgG levels in both cynomolgus monkeys and healthy volunteers. In humans, single administration of efgartigimod reduced IgG levels up to 50%, while multiple dosing further lowered IgGs on average by 75% of baseline levels. Approximately 8 weeks following the last administration, IgG levels returned to baseline. Efgartigimod did not alter the homeostasis of albumin or Igs other than IgG, and no serious adverse events related to efgartigimod infusion were observed.

CONCLUSION

Antagonizing FcRn using efgartigimod is safe and results in a specific, profound, and sustained reduction of serum IgG levels. These results warrant further evaluation of this therapeutic approach in IgG-driven autoimmune diseases.

TRIAL REGISTRATION

Clinicaltrials.gov NCT03457649.

FUNDING

argenx BVBA.

Lower serum IgA is associated with COPD exacerbation risk in SPIROMICS

Background

Decreased but measurable serum IgA levels (≤70 mg/dL) have been associated with risk for infections in some populations, but are unstudied in COPD. This study tested the hypothesis that subnormal serum IgA levels would be associated with exacerbation risk in COPD.

Methods

Data were analyzed from 1,049 COPD participants from the observational cohort study SPIROMICS (535 (51%) women; mean age 66.1 (SD 7.8), 338 (32%) current smokers) who had baseline serum IgA measured using the Myriad RBM biomarker discovery platform. Exacerbation data was collected prospectively (mean 944.3 (SD 281.3) days), and adjusted linear, logistic and zero-inflated negative binomial regressions were performed.

Results

Mean IgA was 269.1 mg/dL (SD 150.9). One individual had deficient levels of serum IgA (<7 mg/dL) and 25 (2.4%) had IgA level ≤70 mg/dL. Participants with IgA ≤70 mg/dL were younger (62 vs. 66 years, p = 0.01) but otherwise similar to those with higher IgA. In adjusted models, IgA ≤70 mg/dL was associated with higher exacerbation incidence rates (IRR 1.71, 95% CI 1.01–2.87, p = 0.044) and greater risk for any severe exacerbation (OR 2.99, 95% CI 1.30–6.94, p = 0.010). In adjusted models among those in the lowest decile (<120 mg/dL), each 10 mg/dL decrement in IgA (analyzed continuously) was associated with more exacerbations during follow-up (β 0.24, 95% CI 0.017–0.46, p = 0.035).

Conclusions

Subnormal serum IgA levels were associated with increased risk for acute exacerbations, supporting mildly impaired IgA levels as a contributing factor in COPD morbidity. Additionally, a dose-response relationship between lower serum IgA and number of exacerbations was found among individuals with serum IgA in the lowest decile, further supporting the link between serum IgA and exacerbation risk. Future COPD studies should more comprehensively characterize immune status to define the clinical relevance of these findings and their potential for therapeutic correction.

Peripheral CD19hi B cells exhibit activated phenotype and functionality in promoting IgG and IgM production in human autoimmune diseases

Systemic Lupus Erythematosus (SLE) and pemphigus are two representative autoimmune diseases driven by pathogenic autoantibody systemically and organ-specifically, respectively. Given the involvement of antibody in the pathogenesis, B cells are inclined to differentiate and function in an abnormal activation model. Here we defined a unique CD19^hi B cell population existing in the periphery of SLE and pemphigus patients as well as in human tonsils. CD19^hi B cells could be induced in vitro after co-culturing fully activated CD4⁺ T cells with autologous B cells. They expressed high levels of HLA-DR, IgG, IgM and multiple ligands of costimulatory molecules with the capacity to produce extra IgG and IgM. Transcirptome assay revealed that genes involved in B-cell activation and differentiation were up-regulated in CD19^hi B cells. Antibody blockade experiments showed that the interactions between costimulatory molecules contributed to CD19^hi B-cell generation and IgG/IgM production. What is more, frequencies of peripheral CD19^hi B cells from SLE and pemphigus patients were correlated with serum total IgG and IgM, but not with autoantigen-specific antibodies and disease severity. Therefore, our investigation demonstrates that CD19^hi B cells might contain B cell precursors for terminal differentiation and contribute to total IgG/IgM production in human autoimmune diseases.

Correlation of hypogammaglobulinaemia with proteinuria, and the relationship between hypogammaglobulinaemia and infection in active lupus nephritis

Objective

To evaluate hypogammaglobulinaemia and risk of serious infectious adverse events in active lupus nephritis.

Methods

The Abatacept and Cyclophosphamide Combination Efficacy and Safety Study (ACCESS) compared abatacept with placebo in participants with lupus nephritis undergoing treatment with Euro-Lupus Nephritis low-dose cyclophosphamide. Serum IgG levels were assessed prior to initiation of treatment and throughout the trial. Hypogammaglobulinaemia was defined as IgG <450 mg/dL.

Results

Hypogammaglobulinaemia was observed in 16/102 (15.7%) participants prior to initiation of induction therapy for active lupus nephritis. Participants with nephrotic range proteinuria were more likely to have hypogammaglobulinaemia, and serum IgG levels were inversely correlated with urine protein to creatinine ratio (r=−0.42, p<0.0001). Following initiation of treatment for active lupus nephritis, additional participants developed hypogammaglobulinaemia by weeks 2–4. Serum IgG levels then increased, and all but one participant had serum IgG ≥450 mg/dL at 24 weeks. Hypogammaglobulinaemia was not associated with an increased risk of serious infectious adverse events.

Conclusions

In active lupus nephritis in ACCESS, hypogammaglobulinaemia was common and inversely correlated with proteinuria. Serum IgG levels were lowest in the weeks immediately following initiation of induction therapy, and subsequently improved by 24 weeks. Hypogammaglobulinaemia was not associated with serious infectious adverse events.

Trial registration

Shorter leukocyte telomere length is associated with higher risk of infections: a prospective study of 75,309 individuals from the general population

In the general population, older age is associated with short leukocyte telomere length and with high risk of infections. In a recent study of allogeneic hematopoietic cell transplantation for severe aplastic anemia, long donor leukocyte telomere length was associated with improved survival in the recipients. These findings suggest that leukocyte telomere length could possibly be a marker of immune competence. Therefore, we tested the hypothesis that shorter leukocyte telomere length is associated with higher risk of infectious disease hospitalization and infection-related death. Relative peripheral blood leukocyte telomere length was measured using quantitative polymerase chain reaction in 75,309 individuals from the general population and the individuals were followed for up to 23 years. During follow up, 9228 individuals were hospitalized with infections and infection-related death occurred in 1508 individuals. Shorter telomere length was associated with higher risk of any infection (hazard ratio 1.05 per standard deviation shorter leukocyte telomere length; 95% confidence interval 1.03–1.07) and pneumonia (1.07; 1.03–1.10) after adjustment for conventional infectious disease risk factors. Corresponding hazard ratios for infection-related death were 1.10 (1.04–1.16) for any infection and 1.11 (1.04–1.19) for pneumonia. Telomere length was not associated with risk of skin infection, urinary tract infection, sepsis, diarrheal disease, endocarditis, meningitis or other infections. In conclusion, our findings indicate that leukocyte telomere length may be a marker of immune competence. Further studies are needed to determine whether risk of infections in allogeneic hematopoietic cell transplantation recipients can be reduced by considering donor leukocyte telomere length when selecting donors.

Recurrent infections in a patient with psoriatic arthritis and hypogammaglobulinemia, treated with conventional and biologic disease-modifying anti-rheumatic drugs-a primary or secondary entity?

A 54-year-old man with confirmed psoriatic arthritis, treated with conventional and biologic disease-modifying anti-rheumatic drugs, suffered from severe, recurrent respiratory tract infections. He was found to have hypogammaglobulinemia. Further investigations confirmed the diagnosis of common variable immunodeficiency. Introduction of immunoglobulin G replacement therapy allowed for safe and effective treatment of psoriatic arthritis with etanercept and methotrexate. Patients with a history of recurrent infections on disease-modifying anti-rheumatic drugs and hypogammaglobulinemia should be assessed for primary antibody immunodeficiencies, even in adulthood.

Effect of Continuous B Cell Depletion With Rituximab on Pathogenic Autoantibodies and Total IgG Levels in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

OBJECTIVE

To evaluate the effect of rituximab on pathogenic autoantibodies and total Ig levels, and to identify serious adverse events in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) treated with continuous B cell depletion.

METHODS

We conducted a retrospective analysis of 239 patients with AAV treated with rituximab-induced continuous B cell depletion. Two treatment cohorts were analyzed: an induction group (n = 52) and a maintenance group (n = 237). Changes in ANCA titers and total Ig levels over time were evaluated using mixed-effects models. Risk factors for serious infections during maintenance treatment were evaluated using Poisson regression.

RESULTS

During induction, IgG levels fell at a mean rate of 6% per month (95% confidence interval [95% CI] 4, 8%), while ANCA levels declined at a mean rate of 47% per month (95% CI 42, 52%) and 48% per month (95% CI 42, 54%) for patients with antimyeloperoxidase (anti-MPO) antibodies and those with anti-proteinase 3 (anti-PR3) antibodies, respectively. During maintenance treatment, with a median duration of 2.4 years (interquartile range 1.5, 4.0 years), IgG levels declined a mean of 0.6% per year (95% CI -0.2, 1.4%). New significant hypogammaglobulinemia (IgG level of <400 mg/dl) during maintenance treatment occurred in 4.6% of the patients, all of whom were in the lowest baseline IgG quartile. Serious infections during maintenance therapy occurred at a rate of 0.85 per 10 patient-years (95% CI 0.66, 1.1) and were independently associated with an IgG level of <400 mg/dl.

CONCLUSION

B cell-targeted therapy causes a preferential decline in ANCA titers relative to total IgG levels. Despite prolonged maintenance therapy with rituximab, IgG levels remain essentially constant. Serious infections were rare.

Structural optimization of an aptamer generated from Ligand-Guided Selection (LIGS) resulted in high affinity variant toward mIgM expressed on Burkitt's lymphoma cell lines

Aptamers are synthetic, short nucleic acid molecules capable of specific target recognition. Aptamers are selected using a screening method termed Systematic Evolution of Ligands by Exponential enrichment (SELEX). We recently have introduced a variant of SELEX called "Ligand-Guided-Selection" (LIGS) that allows the identification of specific aptamers against known cell-surface proteins. Utilizing LIGS, we introduced three specific aptamers against membrane-bound IgM (mIgM), which is the hallmark of B cells. Out of the three aptamers selected against mIgM, an aptamer termed R1, in particular, was found to be interesting due to its ability to recognize mIgM on target cells and then block anti-IgM antibodies binding their antigen. We systematically truncated parent aptamer R1 to design shorter variants with enhanced affinity. Importantly, herein we show that the specificity of the most optimized variant of R1 aptamer is similar to that of anti-IgM antibody, indicating that the specificity of the ligand utilized in selective elution of the aptamer determines the specificity of the LIGS-generated aptamer. Furthermore, we report that truncated variants of R1 are able to recognize mIgM-positive human B lymphoma BJAB cells at physiological temperature, demonstrating that LIGS-generated aptamers could be re-optimized into higher affinity variants. Collectively, these findings show the significance of LIGS in generating highly specific aptamers with potential applications in biomedicine.

Comparison of Serum rAAV Serotype-Specific Antibodies in Patients with Duchenne Muscular Dystrophy, Becker Muscular Dystrophy, Inclusion Body Myositis, or GNE Myopathy

Recombinant adeno-associated virus (rAAV) is a commonly used gene therapy vector for the delivery of therapeutic transgenes in a variety of human diseases, but pre-existing serum antibodies to viral capsid proteins can greatly inhibit rAAV transduction of tissues. Serum was assayed from patients with Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD), inclusion body myositis (IBM), and GNE myopathy (GNE). These were compared to serum from otherwise normal human subjects to determine the extent of pre-existing serum antibodies to rAAVrh74, rAAV1, rAAV2, rAAV6, rAAV8, and rAAV9. In almost all cases, patients with measurable titers to one rAAV serotype showed titers to all other serotypes tested, with average titers to rAAV2 being highest in all instances. Twenty-six percent of all young normal subjects (<18 years old) had measurable rAAV titers to all serotypes tested, and this percentage increased to almost 50% in adult normal subjects (>18 years old). Fifty percent of all IBM and GNE patients also had antibody titers to all rAAV serotypes, while only 18% of DMD and 0% of BMD patients did. In addition, serum-naïve macaques treated systemically with rAAVrh74 could develop cross-reactive antibodies to all other serotypes tested at 24 weeks post treatment. These data demonstrate that most DMD and BMD patients should be amenable to vascular rAAV-mediated treatment without the concern of treatment blockage by pre-existing serum rAAV antibodies, and that serum antibodies to rAAVrh74 are no more common than those for rAAV6, rAAV8, or rAAV9.