Identification of human autoantibodies to the transcriptional repressor ZF5.

ZF5 was originally cloned as a transcriptional repressor on the mouse c-myc promoter. It contains the Kruppel-type zinc fingers and a conserved POZ domain, which is found in a growing number of zinc finger proteins and mediate protein-protein interactions. Autoantibodies against transcription factors are sometimes found in sera from patients with high levels of anti-nuclear antibody (ANA). Using Western blotting with ZF5 and sera of autoimmune disease, we detected one serum, named M6 serum, which contains the antibody against a transcriptional repressor ZF5. The confirmed epitope was specific to ZF5 and was not reactive to the other analogous factors: BCL-6, ZID, and Sp1. This epitope also has a molecular mimicry of the viral proteins. From these results, we predict that viral protein which mimics host ZF5 antigen triggers self-reactive T cell clones and induces the autoantibody in M6 serum after the destruction of host tissues.