University medical center Göttingen
Neuropathology

Author Of 2 Presentations

Neuromyelitis Optica and Anti-MOG Disease Poster Presentation

P0758 - The role of peripheral autoreactive antibodies in initiation and propagation of central nervous system demyelinating disorders (ID 1027)

Speakers
Presentation Number
P0758
Presentation Topic
Neuromyelitis Optica and Anti-MOG Disease

Abstract

Background

Until recently, the function of B cell-derived antibodies in central nervous system (CNS) demyelinating disorders has mainly consisted in amplifying ongoing demyelination by complement fixation. With the discovery of antibodies against the water channel aquaporin-4 in the serum of neuromyelitis optica patients, evidence condensed that autoreactive antibodies may also elicit CNS inflammation. However, for another subgroup of patients with CNS demyelinating disorder, which show antibodies against myelin oligodendrocyte glycoprotein (MOG) in the blood, the precise role of these antibodies remains unknown.

Objectives

We hypothesize that in anti-MOG antibody positive patients, MOG-reactive antibodies in the periphery are capable of opsonizing endogenous MOG protein, subsequently triggering CNS inflammation and demyelination. To prove this assumption, we intend to investigate the effect of serum from these patients on the internalization of soluble and membrane-bound MOG protein by generated human antigen-presenting cells.

Methods

For the generation of dendritic cells and macrophages, CD14+ myeloid cells were isolated from human peripheral blood mononuclear cells of healthy donors and cultured in the presence of distinct cytokines. Expression of Fcγ receptors as well as antigen uptake by the generated antigen-presenting cells were analyzed by flow cytometry.

Results

Flow cytometry analysis of the generated cells revealed that macrophages highly expressed Fcγ receptors I, II and III. By contrast, dendritic cells only highly expressed Fcγ receptor II. Both dendritic cells and macrophages internalized fluorescently labeled MOG and ovalbumin protein, and the addition of a phagocytosis inhibitor diminished protein uptake. Furthermore, the phagocytosis activity of the generated cells was increased in the presence of rabbit anti-ovalbumin antibodies, indicating that soluble protein can be functionally opsonized by these antibodies.

Conclusions

Generated antigen-presenting cells were capable of internalizing soluble protein and rabbit anti-ovalbumin antibodies mediated opsonization of ovalbumin protein, resulting in an enhanced antigen uptake. In ongoing experiments, we investigate the effect of whole immunoglobulin G from anti-MOG antibody positive patients on the internalization of soluble and membrane-bound MOG protein by human antigen-presenting cells.

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Pathogenesis – Immunology Poster Presentation

P0948 - CD20+ T cells emerge from pathogenic B cell- T cell interaction (ID 1685)

Speakers
Presentation Number
P0948
Presentation Topic
Pathogenesis – Immunology

Abstract

Background

B cell depleting anti-CD20 antibodies (ab) are highly effective in multiple sclerosis (MS). Besides B cells, a population of proinflammatory T cells express CD20. The origin of these CD20 positive T cells and whether their depletion contributes to the clinical effect of anti-CD20 is unclear.

Objectives

This study is focused on characterizing CD20+ T cells both in naive and experimental autoimmune encepahalomyelitis (EAE) mice and in humans.

Methods

CD20+ T cells were analyzed for their phenotype, cytokine expression and developmental state using flow cytometry, FACS, ELISA, RT pcr and microscopy. Spleens, inguinal lymph nodes, blood and spinal cord from wild type, 2D2, µMT and CD20KO mice as well as PBMCs from MS patients were examined. Splenoculture and B cell-T cell coculture with 2D2 T cells and various B cells (wt, CD20KO, membrane stained) were used to analyze CD20 content and transfer. EAE was induced by immunization of the mice with CFA and MOG peptide.

Results

When compared to CD20- T cells, CD20+ T cells show enhanced features of pathogenicity both in mice as well as in patients with MS. In wild-type mice, CD20+ T cells expand during EAE, while B cell-deficient mice do not exhibit CD20+ T cells. T cells themselves are not able to generate CD20 and in splenocyte cultures, de novo development of CD20+ T cells is strictly dependent on the presence of B cells expressing CD20. In direct B cell-T cell cocultures, CD20 is transferred from B cells to T cells via trogocytosis. Along the same lines, transfer of CD20 expressing B cells into B cell-deficient mice results in the development of CD20+ T cells.

Conclusions

CD20 on T cells relies on its transfer from B cells via trogocytosis. Thus, T cell CD20 is a marker for their recent activating interaction with a B cell, explaining the pronounced pro-inflammatory phenotype of these T cells. These data suggest that depletion of CD20+ T cells may substantially support the effectiveness of anti-CD20 ab therapy in MS, and their reappearance in the blood may serve as a marker for reemerging pathogenic B cell – T cell interaction.

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