Specificity of anti-neutrophil cytoplasmic autoantibodies for proteinase 3 (1)
A 29 kDa neutrophil serine proteinase was identified as an autoantigen of anti-neutrophil cytoplasmic autoantibodies (ANCA) in patients with Wegner’s granulomatosis. Myeloperoxidase (MPO) has been known as an autoantigen. In addition, Since ANCA has recognized proteinase 3 (PR3), the 29 kDa protein can be identical with PR3. In western blot analysis, ANCA sera reacted to a 29-kDa fraction of neutrophil cytoplasm (29-kDa ANCA), but MPO-specific ANCA did not react with the 29-kD a band. In ELISA, 29-kDa ANCA sera reacted with purified PR3 statistically significant.
Furthermore, The ANCA staining pattern produced by 29-kDa ANCA was blocked by anti-PR3 monoclonal antibodies and anti-DNA monoclonal antibodies. The MPO-ANCA staining was blocked by anti-MPO monoclonal antibodies, but not by anti-PR3 antibodies. Thus, the newly identified 29 kDa protein is highly identical with PR3.
However, the amino acid sequence analysis showed that they are similar sequences but not 100% identical. Further investigation will be required.