A Highly Sensitive Live Cell Based Assay for Detection of Antibodies Against N-methyl-d-aspartate Receptors

Abstract

breakdown of immune tolerance; a phenomenon associated with the development of Multiple Sclerosis (MS). B lymphocytes are key players in the pathogenesis of MS and, while B lymphocytes are traditionally regarded as promoters of the immune response via antibody secretion and cytokine production, recent studies have confirmed an important role for these lymphocytes in the negative regulation of immunity. Within this scenario, BTLA, a novel inhibitory receptor that ligates B7 familymember proteins, was identified. Similar to CTLA-4 and PD-1, BTLA is expressed on activated B and T cells alone. Binding of BTLA to B7-H4 (B7S1, B7x), its putative ligand, inhibits TCRinitiated cytokine production and cell cycle progression, suggesting a role for BTLA in peripheral tolerance; its possible involvement in MS is nevertheless still unknown. Recently a novel subset of regulatory B lymphocytes (Breg) known as B10 cells, which regulate immune responses through the production of the anti-inflammatory cytokine interleukin-10 (IL-10), was identified. Objectives: To define the possible role of B cells in the pathogenesis of MS. Methods: We analysed by flow-cytometry the surface expression of BTLA, as well as IL-10 and TGF beta production, in un-stimulated or in myelin oligodendrocyte glycoprotein (MOG)-stimulated CD19+ B lymphocytes of MS patients with a clinical and MRI diagnosis of either relapsing-remitting (RRMS), chronic progressive (CPMS), or benign MS (BEMS); results were compared to those obtained in age and sex matched healthy controls (HC). Results: Whereas no differences were seen in un-stimulated cells, MOG-stimulated, BTLA-expressing CD19+ cells were augmented in BEMS and HC compared to all the other patients (p b 0.01); IL-10and TGFbeta-producing CD19+ Breg were augmented as well in MOG-stimulated cells of BEMS and HC compared to RRMS and CPMS groups. Conclusions: Data herein indicate that a quantitative and qualitative impairment of Breg accompanies the breakdown of immune tolerance associated with MS. Because a significant increase of Bregs and of BTLA-expressing CD19+ cells was seen in BMS, a regulatory role in preventing disease progression could be envisioned for these cells. These results could help the design of novel diagnostic and therapeutic approaches to MS. Monitoring BTLA expression could be a novel prognostic tool in MS patients. Grant by the Italian Ministry of Health: Ricerca Corrente 2013–14.