The IgG subclass-specificities of anti-IFNβ antibodies change with time and differ between the IFNβ products in relapsing remitting multiple sclerosis patients

High serum IgG subclass concentrations in children with e-waste Pb and Cd exposure

Immunoglobulin G (IgG) is the predominant component of the humoral immune system. Epidemiological studies have shown that lead (Pb) or cadmium (Cd) exposure is associated with changes in human IgG levels, and alteration of IgG subclass production can be induced by differential modulation of Th1 and Th2 cytokines caused by Pb or Cd exposure. However, no study has focused on the adverse effects of Pb and Cd co-exposure on IgG subclass production by regulating Th1/Th2 cytokines in children living in electronic waste (e-waste) areas. This study aims to analyze the associations among Pb and Cd in blood, Th1/Th2 cytokines, and IgG subclasses in serum from children. A total of 181 healthy, 2- to 7-year-old children were examined. Of them, 104 were from Guiyu (e-waste exposed group), and the rest were from Haojiang (reference group) in China. Pb and Cd levels in whole blood, cytokines, and IgG subclasses in serum were determined. Exposed children had higher levels of blood Pb and Cd, serum IgG1, IgG1 + IgG2, serum Th1 cytokine interferon-γ (IFN-γ) and lower levels of the Th2 cytokine interleukin (IL)-13. Increased blood Pb levels were positively associated with serum levels of IFN-γ, and negatively associated with serum levels of IL-13. Adjusted linear regression analysis showed that serum levels of IL-13 were negatively associated with serum levels of IgG1 and IgG1 + IgG2. Mediation models indicated that IL-13 had significant mediating effects on the relationships between blood Pb levels and serum IgG1, as well as between blood Pb levels and serum IgG1 + IgG2. Increased blood Cd levels were positively associated with serum levels of IgG1. Our results show heavy metal (particularly Pb) exposure may affect IgG subclass production by regulating Th1/Th2 cytokines in exposed children, thus providing new evidence for a relationship between humoral immune function and environmental exposure.

Persistency of Neutralizing Anti-Interferon-β Antibodies in Patients with Multiple Sclerosis Treated with Subcutaneous Interferon-β Depends on Antibody Titers, IgG Subclasses, and Affinity Maturation

Neutralizing antibodies may affect interferon (IFN)-β treatment efficacy, but mechanisms of neutralizing anti-drug antibody (ADA) evolution are not fully elucidated. We investigated the relationship between ADA titers, IgG subclass profile, and binding affinity with the development and persistency of neutralizing ADA in relapsing-remitting multiple sclerosis (MS) patients treated with subcutaneous IFN-β. A total of 94 patients, who had blood sampling at months 6, 12, 24, and 36 during IFN-β therapy, were included into this retrospective study and stratified to the following: non-neutralizing, transient, and persistent neutralizing ADA status. Patients without or with transient neutralizing ADA displayed predominantly IgG₁ and IgG₃ subclasses, lower ADA titers, and antibody binding affinity compared with patients having persistent neutralizing ADA, in whom the predominant IgG subclasses were IgG₂ and IgG₄. Overall, ADA binding affinity positively correlated with IgG₄ and neutralizing ADA titers, but negatively with IgG₃ titers. Persistency of neutralizing ADA was predicted by their titers at month 24 and month 36 of treatment and by an increase of antibody affinity within the second year of IFN-β treatment. The humoral immune response to IFN-β observed in MS patients as a result of IFN-β therapy is a multifactorial process that is influenced by ADA titers, affinity maturation, and IgG subclass switching.

Antibody dissociation rates are predictive of neutralizing antibody (NAb) course: a comparison of interferon beta-1b-treated Multiple Sclerosis (MS) patients with transient versus sustained NAbs

A proportion of multiple sclerosis (MS) patients treated with interferon-β (IFNβ) develop neutralizing antibodies (NAbs), which can reduce therapeutic efficacy. In the Betaseron/Betaferon in Newly Emerging MS for Initial Treatment (BENEFIT) study, 88/277 patients developed NAbs, 48 having transient positivity and 29 having sustained positivity. This study aimed to investigate the antibody binding characteristics of serial sera in a subset of these two patient groups. Using Biacore™, a surface plasmon resonance-based technology that monitors biomolecular interactions in real time, we immobilized pure IFNβ-1b and analyzed antibody binding responses and dissociation rates of these sera. NAb titers correlated directly with binding responses and inversely with dissociation rates, and sera from sustained NAb patients demonstrated significantly higher binding responses and slower dissociation rates than sera from transient NAb patients. Thus, transient and sustained NAbs are quantitatively and qualitatively different, and interestingly, binding responses and dissociation rates at month 12 could predict the NAb course.

Immunoglobulin G1 and immunoglobulin G4 antibodies in multiple sclerosis patients treated with IFNβ interact with the endogenous cytokine and activate complement

A subset of patients with relapsing-remitting multiple sclerosis (RRMS) on therapy with interferon beta (IFNβ) develop neutralising anti-drug antibodies (ADA) resulting in reduced, or loss of, therapeutic efficacy. The aims were to characterise the relative contributions of anti-IFNβ antibody isotypes to drug neutralising activity, ability of these antibodies to cross-react with endogenous IFNβ, to form immune complexes and activate complement. IFNβ-specific ADA were measured in plasma from RRMS patients treated with IFNβ1a (Rebif^®). Neutralisation of endogenous and therapeutic IFNβ by ADA was determined by IFNβ bioassay. IFNβ-ADA profile was predominantly comprised of IgG1 and IgG4 antibody isotypes. The contribution of IgG4-ADA towards neutralising activity was found to be minimal. Neutralising IFNβ-ADA blocks endogenous IFNβ activity. ADA interaction with therapeutic IFNβ results in immune complex formation and complement activation. In summary, IgG1 and IgG4 IFNβ-ADA have the ability to neutralise therapeutic and endogenous protein and to activate complement.

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IgG4 and IgG1 contributes to IFNβ-ADA profile

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Neutralising IFNβ-ADA cross reacts and blocks endogenous IFNβ activity.

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ADA-IFNβ results in IC formation and complement activation

Characterization of anti-natalizumab antibodies in multiple sclerosis patients

BACKGROUND

A small proportion of multiple sclerosis (MS) patients treated with natalizumab develop anti-drug antibodies.

OBJECTIVE

The objective of this paper is to characterize the anti-natalizumab antibody response and to investigate differences between persistently and transiently antibody-positive patients.

METHODS

Screening for anti-natalizumab antibodies was performed using a standardized bridging ELISA. Antibody-positive samples were further analyzed for IgM and IgG1-4 antibodies using ELISA and ImmunoCAP®.

RESULTS

Anti-natalizumab antibodies developed in 57 of 1379 (4.1%) treated patients after a median treatment duration of three months. Of the positive patients, 20 (35%) patients reverted to negative, 19 (33%) patients were confirmed persistently positive and 18 (32%) patients were unconfirmed positive. Significantly higher anti-natalizumab antibody levels were detected in persistently compared to transiently positive patients. A cutoff value predicting persistence of antibodies could be determined with a sensitivity of 0.84 and a specificity of 0.80. IgM and IgG4 antibody levels were significantly higher in persistently compared to transiently positive patients, and IgG1, IgG2 and IgG4 increased significantly over time.

CONCLUSIONS

The level of total anti-natalizumab antibodies in a first positive sample can be used to predict patients at risk for persisting antibody positivity. However, neither IgM nor IgG1-4 antibodies could be used to discriminate between transiently and persistently positive patients.

Prevalence of anti-drug antibodies against interferon beta has decreased since routine analysis of neutralizing antibodies became clinical practice

BACKGROUND

Neutralizing antibodies (NAbs) against interferon beta (IFNβ) lead to loss of treatment efficacy in multiple sclerosis patients. The seroprevalence of NAbs in multiple sclerosis patients treated with IFNβ during 2003-2004 was 32% in a cross-sectional analysis of routine data.

OBJECTIVES

The aim of this study was to investigate whether the seroprevalence of NAbs, the levels of NAb titres and the IFNβ preparations used for treatment of multiple sclerosis patients had changed in 2009-2010.

METHODS

This study included 1296 patients, analysed for NAbs with the myxovirus resistance protein A gene expression assay in 2009-2010.

RESULTS

The seroprevalence of NAbs had decreased to 19% in 2009-2010, which is significantly lower compared with the previous study in 2003-2004 (p<0.0001). This decrease was attributed to the IFNβ-1a preparations only, not to IFNβ-1b. The frequency of patients with high positive titres decreased the most, from 16% to 7% (p<0.0001).

CONCLUSIONS

NAb seroprevalence has decreased since NAb monitoring became clinical practice in 2003, especially for patients with high NAb titres. This might be due to the stricter monitoring of NAb titres that prompt NAb positive patients to stop treatment, to preferential use of less immunogenic drugs and to alteration of drug formulations.

The clinical effect of neutralizing antibodies against interferon-beta is independent of the type of interferon-beta used for patients with relapsing-remitting multiple sclerosis

Objective

To establish whether the clinical effect of neutralizing antibodies (NAbs) against interferon-beta (IFNβ) depends on the type of IFNβ (1a or 1b) used for treatment of patients with relapsing-remitting multiple sclerosis (MS).

Introduction

NAbs against IFNβ-1b appear faster and may be more evenly distributed on IgG subclasses, whereas NAbs against IFNβ-1a develop more slowly and may be devoid of IgG3. This might cause different clinical responses to NAbs.

Design/patients

All Danish MS-patients who had started first-time treatment with IFNβ-1a 22 μg s.c tiw (Rebif22) or IFNβ-1b 250 μg s.c. qod (Betaferon) before January 1st 2003 were included. Relapses were recorded at bi-annual visit.

Methods

We measured NAbs every 12 months using a clinically validated cytopathic effect assay. A blood sample with a neutralizing capacity of 20% or more was considered as NAb-positive. We used a mixed logistic regression analysis in which NAb-status (three levels), IFNβ-preparation, and time since treatment started were included as explanatory variables, and relapse rate as response variable.

Results

In 1,309 patients, who were observed for 21,958 months, 32.3% were classified as NAb-positive. The odds-ratio (OR) for relapses in NAb-positive months compared with NAb-negative months was 1.25; P = 0.02. The risk of relapses was higher with Betaferon than with Rebif22 (OR 1.26; P < 0.01). The effect of NAb-level on relapses was independent of whether the patients were treated with Betaferon or Rebif22 ( P = 0.89) and of time ( P = 0.80).

Conclusion

NAbs caused by IFNβ-1a s.c. do not differ from NAbs caused by IFNβ-1b in their detrimental clinical effect.