Presentation of the candidate rheumatoid arthritis autoantigen aggrecan by antigen-specific B cells induces enhanced CD4(+) T helper type 1 subset differentiation.
ABSTRACT Effective immune responses require antigen uptake by antigen-presenting cells (APC), followed by controlled endocytic proteolysis resulting in the generation of antigen-derived peptide fragments that associate with intracellular MHC class II molecules. The resultant peptide-MHC class II complexes then move to the APC surface where they activate CD4(+) T cells. Dendritic cells (DC), macrophages and B cells act as efficient APC. In many settings, including the T helper type 1 (Th1) -dependent, proteoglycan-induced arthritis model of rheumatoid arthritis, accumulating evidence demonstrates that antigen presentation by B cells is required for optimal CD4(+) T cell activation. The reasons behind this however, remain unclear. In this study we have compared the activation of CD4(+) T cells specific for the proteoglycan aggrecan following antigen presentation by DC, macrophages and B cells. We show that aggrecan-specific B cells are equally efficient APC as DC and macrophages and use similar intracellular antigen-processing pathways. Importantly, we also show that antigen presentation by aggrecan-specific B cells to TCR transgenic CD4(+) T cells results in enhanced CD4(+) T cell interferon-γ production and Th1 effector sub-set differentiation compared with that seen with DC. We conclude that preferential CD4(+) Th1 differentiation may define the requirement for B cell APC function in both proteoglycan-induced arthritis and rheumatoid arthritis.
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ABSTRACT: How certain autoimmune diseases target specific organs remains obscure. In the 'K/BxN' arthritis model, autoantibodies to a ubiquitous antigen elicit joint-restricted pathology. Here we have used intravital imaging to demonstrate that transfer of arthritogenic antibodies caused macromolecular vasopermeability localized to sites destined to develop arthritis, augmenting its severity. Vasopermeability depended on mast cells, neutrophils and FcgammaRIII but not complement, tumor necrosis factor or interleukin 1. Unexpectedly, radioresistant FcRgamma-expressing cells in an organ distant from the joint were required. Histamine and serotonin were critical, and systemic administration of these vasoactive amines recapitulated the joint localization of immune complex-triggered vasopermeability. We propose that regionally distinct vascular properties 'interface' with immune effector pathways to foster organ-specific autoimmune damage, perhaps explaining why arthritis accompanies many human infectious and autoimmune disorders.Nature Immunology 04/2006; 7(3):284-92. · 26.01 Impact Factor
Article: Chimeric antibody with human constant regions and mouse variable regions directed against carcinoma-associated antigen 17-1A.[show abstract] [hide abstract]
ABSTRACT: We have cloned the genomic DNA fragments encoding the heavy and light chain variable regions of monoclonal antibody 17-1A, and we have inserted them into mammalian expression vectors containing genomic DNA segments encoding human gamma 3 and kappa constant regions. The transfer of these expression vectors containing mouse-human chimeric immunoglobulin genes into Sp2/0 mouse myeloma cells resulted in the production of functional IgG that retained the specific binding to the surface antigen 17-1A expressed on colorectal carcinoma cells.Proceedings of the National Academy of Sciences 02/1987; 84(1):214-8. · 9.68 Impact Factor
Article: B-cells and their targeting in rheumatoid arthritis--current concepts and future perspectives.[show abstract] [hide abstract]
ABSTRACT: Rheumatoid arthritis (RA) is a chronic, autoimmune disease that affects primarily the joints and without proper treatment results in their progressive destruction. In addition to T-cells, B-cells play a central role in the pathogenesis of this disease. The synovial tissue is an active site of B-cell accumulation, plasma cell differentiation and in situ antibody-production in RA. As part of the complex role of B-cells in the joints and synovial membrane of RA patients, B cells secrete chemokines and cytokines and may function as antigen presenting cells. The multifaceted pathogenic function of B-cells identifies them as excellent targets for immunosuppressive therapy. B-cell targeting involves a wide spectrum of molecules, for example the B-cell antigen CD20 that allows specific and effective B-cell depletion. Another target, CD79, expressed by B-cell and plasma cell precursors is an obvious candidate that induces apoptosis as well as inhibition of B-cell receptor (BCR) activation and possibly depletion of ectopic germinal centers (GC). Inhibition of B-cell co-stimulatory molecules such as CD40, CD80/86 and ICOS, can lead to diminished B-cell activation. Moreover, anti-chemokine and anti-cytokine therapies can be efficacious in RA by the disruption of B-cell activation and autoantibody production, B-cell synovial migration and ectopic GC formation. Finally, targeting the signal transduction pathways required for proximal BCR signaling has also been found efficacious in early clinical trials in RA. Even so, some B cells inhibit immune responses, these regulatory B cells may play a part in immune regulation in patients and it is unclear what effects B cell depletion strategies have in terms of such B cell subsets. This review discusses current strategies of targeting B-cells as therapeutic candidates in the management of RA. Better insights into the pathogenic role of B-cells provide efficacious opportunities to improve both therapy and prognosis of patients with RA.Autoimmunity reviews 07/2011; 11(1):28-34. · 6.37 Impact Factor