Anti-interferon-inducible protein IFI16 autoantibody

Interferon-inducible protein IFIl6 antibody (interfer-on-inducible protein IFIl6 autoantibodies) is a new type of specific anti-nuclear antibody antibody, which can be seen in about one-third of SLE patients. IFI16 is formed by the gene family ifil6, which can also encode bone marrow cell nuclear differentiation antigen (MNDA). Anti-IFI16 autoantibodies can be detected by immunofluorescence.

(2) Autoantigen

1. Definition IFI16 is located at lq21-32 of the human chromosome, and its genomic fragment is composed of 2 800 bases, including 10 exons and 9 inserted introns. The IFI16 protein is composed of 729 amino acids and has a molecular weight of approximately 82-114 kD. The natural IFI16 molecular weight is between 95 and 100kD, which shows the phenomenon of post-translational processing.

2. Source IFI16 mainly exists in the nucleolus and nucleoplasm of human cells. Various human cells, such as endothelial cells, pancreatic acinar epithelial cells, keratinocytes, fibroblasts and adrenal cortical epithelial cells, can express IFIl6 in the nucleus.

3. Characteristics Although there is a connection between IFIl6 and the differentiation of human bone marrow cells, the biological function of IFIl6 in other cells is unclear.

(3) Autoantibodies

1. Synonyms Previously, IFI16 was named after 16P, protein 16P and (interferon-inducible protein) P16. But P16 or 16P is easy to produce ambiguity, because after all, the molecular weight of IFll6 is 90-100kD. Most anti-IFll6 antibodies are of IgG type, and IgM antibodies have also been found in some sera.

2. Detection method Western blot and ELISA using recombinantly expressed IFll6 as antigen can be used to detect anti-IFI16 antibody. When IFI16 antibody was detected by IIF method, Hep-2 cells were the best antigen matrix, and their fluorescence characteristics were strong positive nucleolus staining, and slightly weak nucleoplasm staining.

3. Pathogenic effects About 29% of SLE patients have anti-IFI16 antibody, which has no obvious correlation with anti-dsDNA, anti-RNP, anti-Sm, anti-SSA, and anti-SSB in SLE patients. In addition, there is no obvious relationship between anti-IFI16 antibody and nephritis or Sjogren's syndrome. In addition to being present in patients with SLE, anti-IFIl6 antibodies can also be found in about 3.8% of patients with scleroderma or polymyositis. Anti-IFIl6 was not found in RA patients.

4. I clinical significance Only when other indicators of SLE have been determined, anti-IFIl6 antibody can be used as an additional useful indicator of SLE. At present, it is still too early to apply anti-IFIl6 antibodies for diagnosis; since both bone marrow cells and endothelial cells involved in the inflammatory response can be induced by IFN-γ, IFIl6 is expressed after induction; and IFIl6 is an important mediator of various inflammatory responses. It can activate macrophages, monocytes and B cells, and can also express MHC-II molecules or high-affinity IgG receptors. Therefore, in the process of chronic inflammation, after induction with IFN-γ, it may cause a large amount of antigen production and stimulate the production of self-antigen.