Mechanisms of autoantibody production and the relationship between autoantibodies and the clinical manifestations in Sjögren's syndrome.

The major target organs of Sjögren's syndrome (SS) are lacrimal glands and salivary glands where prominent lymphocytic infiltration occurs, which may induce varying levels of autoantibody production. Multiple factors, including environmental stress, viral infection, hormonal imbalance, and apoptosis, are thought to be involved in the pathogenesis of SS. Production of anti-SS-A/Ro and anti-SS-B/La antibodies is thought to be regulated by the presentation of autoantigens in context with an aberrant expression pattern of human leukocyte antigen (HLA) in situ. Molecular mimicry with some viral sequences is also hypothesized. The apoptosis-resistance phenotype of B cells in labial salivary glands (LSGs) of SS is important in autoantibody production. CD40/CD40L (CD40 ligand) and Bcl-2 family proteins, in tandem with B cell-activating factor (BAFF), are supposed to protect infiltrating lymphocytes from apoptosis. Anti-muscarinic3 receptor antibody plays an important role in cholinergic hyperresponsiveness in SS. Fragmentation of autoantigens such as SS-B/La or alfa-fodrin during the process of apoptosis causes the redistribution of these autoantigens, leading to the production of autoantibodies in SS. In this review, the role of autoantibodies found in SS, corresponding to clinical aspects of each antibody as well as the mechanisms of production, is discussed.