Institute of Clinical Neuroimmunology, University Hospital and Biomedical Center, Ludwig-Maximilians University Munich

Author Of 1 Presentation

Pathogenesis – Immunology Poster Presentation

P0993 - Reconstitution of a pathogenic antibody of a unique case of human autoimmune encephalitis (ID 248)

Speakers
Presentation Number
P0993
Presentation Topic
Pathogenesis – Immunology

Abstract

Background

Multiple sclerosis is a chronic inflammatory demyelinating disease potentially driven by autoimmunity. Active immunization of humans with brain tissue, as shown following rabies vaccination or misguided “cell therapeutic” approaches, can trigger autoimmune encephalomyelitis, which in rare cases may reflect the pathology of multiple sclerosis (Höftberger et al 2015). The specific brain autoantigen(s) recognized by the immune system in such a condition are presently unknown.

Objectives

Aim of our study was to reconstruct dominant auto-antibodies from formalin fixed paraffin embedded brain material of such a case and to test immunoreactivity and pathogenicity of the respective reconstructed recombinant antibodies.

Methods

RNA was isolated of three different lesions sites of this case with large B lineage cell infiltrates for generating libraries for antibody repertoire analysis. Clonally expanded heavy and light immunoglobulin chains were cloned and antibodies were produced and purified using the ExPi293 expression system. Flow cytometry was used to test antibody binding to either full length human, rat or mouse myelin oligodendrocyte glycoprotein (MOG) and different MOG mutants were used to determine the specific antibody binding site. Immunohistochemistry was performed on human brain tissue to confirm the Flow Cytometry data. Finally, we tested the demyelinating activity of the reconstructed recombinant antibody after transfer into rats with T-cell mediated brain inflammation.

Results

We identified clonal expansion of one heavy and one light immunoglobulin chain, which together form a functional antibody (the “hAE antibody”). This antibody recognized human, rat and mouse full length MOG and shared some but not all binding sites to MOG with the 8-18C5 recombinant anti-MOG antibody. The antibody bound to myelin in tissue sections of humans, mice and rats and induced specific primary demyelination with complement activation after passive transfer in rats in vivo.

Conclusions

Our study shows that it is possible to resurrect a disease promoting antibody from formaldehyde fixed and paraffin embedded autopsy tissue of a patient, who died more than 60 years ago. It further shows that like in rodents and primates auto-immunization of humans with brain tissue induces a pathogenic auto-antibody response, which can amplify demyelination in the context of brain inflammation.

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