Autoimmune diseases: nuclear autoantigens can be found at the cell-surface

The pathogenesis of autoimmune diseases is only partially understood. In particular, the question remains why many nuclear proteins have been identified as autoantigens. One possible mechanism for an autoimmune response to nuclear proteins involves their exposure to the immune system. In this report we discuss currently available data on the exposure of nuclear proteins by expression at the cell-surface. Although the pathways of surface expression remain unclear, the presence of nuclear proteins at the cell-surface might reflect a pathological reaction leading to an exposure of epitopes, e.g. to self-reactive B-cells. It is suggested that cell-surface expression of intracellular proteins can contribute to the generation of autoimmune diseases.