Increased frequencies of myelin oligodendrocyte glycoprotein/MHC class II-binding CD4 cells in patients with multiple sclerosis

MHC class II tetramers

MHC class II tetramers have emerged as an important tool for characterization of the specificity and phenotype of CD4 T cell immune responses, useful in a large variety of disease and vaccine studies. Issues of specific T cell frequency, biodistribution, and avidity, coupled with the large genetic diversity of potential class II restriction elements, require targeted experimental design. Translational opportunities for immune disease monitoring are driving the rapid development of HLA class II tetramer use in clinical applications, together with innovations in tetramer production and epitope discovery.

A novel IL-10-independent regulatory role for B cells in suppressing autoimmunity by maintenance of regulatory T cells via GITR ligand

B cells are important for the regulation of autoimmune responses. In experimental autoimmune encephalomyelitis (EAE), B cells are required for spontaneous recovery in acute models. Production of IL-10 by regulatory B cells has been shown to modulate the severity EAE and other autoimmune diseases. Previously, we suggested that B cells regulated the number of CD4(+)Foxp3(+) T regulatory cells (Treg) in the CNS during EAE. Because Treg suppress autoimmune responses, we asked whether B cells control autoimmunity by maintenance of Treg numbers. B cell deficiency achieved either genetically (μMT) or by depletion with anti-CD20 resulted in a significant reduction in the number of peripheral but not thymic Treg. Adoptive transfer of WT B cells into μMT mice restored both Treg numbers and recovery from EAE. When we investigated the mechanism whereby B cells induce the proliferation of Treg and EAE recovery, we found that glucocorticoid-induced TNF ligand, but not IL-10, expression by B cells was required. Of clinical significance is the finding that anti-CD20 depletion of B cells accelerated spontaneous EAE and colitis. Our results demonstrate that B cells play a major role in immune tolerance required for the prevention of autoimmunity by maintenance of Treg via their expression of glucocorticoid-induced TNFR ligand.

Autoantibodies in Heart Failure and Cardiac Dysfunction

Human heart failure is a disease with multifactorial causes, considerable morbidity, and high mortality. Several circulating autoantibodies, some of them being heart-specific, play a crucial role in the progression and induction of heart failure. However the precise mechanisms on how these autoantibodies perpetuate or even induce an organ specific autoimmune response are not yet fully understood. Also it is being a matter of current research to elucidate a potential pathophysiological role of the innate immune system in generating auto-reactive antibodies. In this review we will summarize the current available literature on circulating autoantibodies which are related to human heart failure. We will present clinical and animal studies that demonstrate the occurrence and pathophysiological relevance of several autoantibodies in heart failure, as well as point out biological mechanisms on molecular and cellular level. Finally the beneficial therapeutic effects of numerous clinical studies that target the humoral arm of the immune system by using either intravenous immunoglobulins and/or immunoadsorption will be critically discussed.

Detection and characterisation of alloreactive T cells

T cell alloreactivity is responsible for much of the morbidity and mortality associated with tissue transplantation and graft versus host disease. Immunoassays for ex vivo monitoring and quantitation of alloreactive T cells are being increasingly utilised to provide valuable information for individualised clinical management of transplant recipients. Here we describe detailed methodologies for both traditional and novel assays utilised for the detection, quantitation, and functional characterisation of alloreactive T cells and highlight the key advantages and disadvantages of each system.

Conformational epitopes of myelin oligodendrocyte glycoprotein are targets of potentially pathogenic antibody responses in multiple sclerosis

Background

Myelin/oligodendrocyte glycoprotein (MOG) is a putative autoantigen in multiple sclerosis (MS). Establishing the pathological relevance and validity of anti-MOG antibodies as biomarkers has yielded conflicting reports mainly due to different MOG isoforms used in different studies. Because epitope specificity may be a key factor determining anti-MOG reactivity we aimed at identifying a priori immunodominant MOG epitopes by monoclonal antibodies (mAbs) and at assessing clinical relevance of these epitopes in MS.

Methods

Sera of 325 MS patients, 69 patients with clinically isolated syndrome and 164 healthy controls were assayed by quantitative, high-throughput ELISA for reactivity to 3 different MOG isoforms, and quantitative titers correlated with clinical characteristics. mAbs defined unique immunodominant epitopes distinct to each of the isoforms.

Results

In the majority of human samples anti-MOG levels were skewed towards low titers. However, in 8.2% of samples high-titer anti-MOG antibodies were identified. In contrast to anti-MOG reactivity observed in a mouse model of MS, in patients with MS these never reacted with ubiquitously exposed epitopes. Moreover, in patients with relapsing-remitting MS high-titer anti-MOG IgG correlated with disability (EDSS; Spearman r = 0.574; p = 0.025).

Conclusions

Thus high-titer reactivity likely represents high-affinity antibodies against pathologically relevant MOG epitopes, that are only present in a small proportion of patients with MS. Our study provides valuable information about requirements of anti-MOG reactivity for being regarded as a prognostic biomarker in a subtype of MS.