Introduction: B cell-mediated autoimmune diseases

Excerpt

This issue of Seminars in Immunopathology centers on the role of autoantibodies and B lymphocytes in various autoimmune diseases. B lymphocytes and autoantibodies play a crucial role in the pathogenesis of an increasing number of diseases. They may serve as antigen-presenting cells, produce pro-inflammatory cytokines, and—most notably—plasma cells as their terminal differentiation state represent the source of autoantibodies that are believed to be often the drivers of immunopathology. When looking closely, however, in many autoimmune diseases, the exact mechanisms of autoantibody-driven pathogenesis are less than clear. Binding of target structures by autoantibodies, activation of the complement cascade with the release of chemotactic and pro-inflammatory peptides and binding of immune complexes by innate immune cells via Fc-receptors and initiation of inflammatory responses are discussed to play crucial roles in antibody-driven autoimmune diseases. In addition, a growing number of diseases or subsets thereof are obviously caused by receptor-binding and their function-modulating antibodies. However, depending on the kind of autoimmune disease, different mechanisms or combinations thereof may govern pathogenesis. For multiple autoimmune diseases, the specificity of autoantibodies serves as an important criterion for diagnosis. These classical “biomarkers” are usually poorly or not at all correlated with disease activity and manifestations, either because we do not yet have sufficient understanding of the most relevant autoantibody specificities or even posttranslational modifications of the autoantigens or because additional immunological and non-immunological processes are the crucial determinants for the pathogenesis of a certain autoimmune disease. …