[Mechanisms of production and pathogenesis of autoantibodies]

Autoantibodies against various cellular components are found in sera from patients with connective tissue diseases. These autoantibodies have been demonstrated to be associated with certain diseases and clinical manifestations, and give us useful information for clinical practice. The development of new technologies for detecting autoantibodies have been able to identify a hundred of autoantibodies and their target autoantigens. They are mostly intracellular enzymes and regulatory factors necessary for important biological function involved in gene replication, repair, transcription, RNA processing and protein translation. The studies of fine structures and functions of target autoantigens have given us important suggestions to understand the mechanisms of autoantibody production and etiology of autoimmune diseases. Most autoantibodies found in systemic autoimmune diseases have been thought to be rather "reporters" of diseases and innocent from direct pathogenic effects. However, certain autoantibodies are supposed to have some pathogenic effect in certain conditions such as anti-SS-A/Ro antibodies and neonatal lupus, although the mechanism is still not clarified. We found that anti-U1RNP antibodies are more concentrated in cerebrospinal fluids than in sera of MCTD patients with aseptic meningitis, suggesting a possible role of the autoantibodies in the development of CNS disease.