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Ординатура / Офтальмология / Английские материалы / Sjögren's Syndrome Diagnosis and Therapeutics_Ramos-Casals, Stone, Moutsopoulos_2012.pdf
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X. Mariette

40.1B-Cell Hyperactivity in Sjögren’s Syndrome

40.1.1Evidence of B-Cell Hyperactivity

B-cell hyperactivity has been recognized for a long time in Sjögren’s syndrome (SS). More than 30 years ago, Talal et al. demonstrated an increased level of beta-2- microglobulin in the serum of patients with SS [1]. More than 20 years ago, Moutsopoulos et al. detected increased levels of immunoglobulin light chains within the sera of patients with SS [2].

B-cell activation in SS is initially polyclonal but can progress to monoclonal B-cell lymphoproliferation [3]. A relative risk of lymphoma of 44 was reported by Kassan et al. in 1978 [4]. A recent study in Sweden and a meta-analysis found a somewhat lower (but still substantially elevated) relative risk, on the order of 16–18 [5, 6]. Lymphomas in SS are prone to develop at sites of inflammation (salivary glands) mediated by infiltrating B-lymphocytes [7, 8]. B-cell hyperactivity in primary SS is evidenced by a polyclonal hypergammaglobulinemia, the presence of autoantibodies such as anti-SSA/Ro and anti-SSB/La, high levels of rheumatoid factor [9], elevated concentrations of beta-2-microglobulin, and free immunoglobulin light chains in the serum. Gottenberg et al. recently demonstrated that serum beta-2-microglobulin and free light chain levels correlated with systemic involvement of the disease [10, 11].

40.1.2An Increase in BAFF Could Explain B-Cell Hyperactivity in SS

A cytokine known as B-cell-activating factor of the tumor necrosis factor family (BAFF), also called B-lymphocyte stimulator (BLyS), TALL-1, THANK, zTNF4, TNFSF13b, or TNFSF20, plays a crucial role in the differentiation and survival of B-cells. Three distinct receptors are essential to normal BAFF physiology: (1) B-cell maturation antigen (BCMA); (2) transmembrane activator, calcium-modulator and cyclophilin ligand interactor (TACI); and (3) BAFF receptor (BAFFR or BR3) [12, 13]. BAFF is produced principally by monocytes, dendritic cells, and macrophages [14].

BAFF transgenic mice first develop a disease that mimics systemic lupus erythematosus (SLE) before evolving a sialadenitis that resembles SS. These mice also have a two-fold elevated risk of lymphoma [15].

40.1.2.1Serum BAFF in SS

One year after the first link between BAFF in SLE in humans, Groom et al. demonstrated elevated serum levels of BAFF in SS patients [16]. Correlations between serum BAFF concentrations, IgG, and rheumatoid factor levels were reported in 2003 [17]. Moreover, patients with anti-SSA/Ro and/or anti-SSB/La antibodies were

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