ANCA-C (Anti PR3 Serine Protease 3 antibody)
Sample: Serum
Schedule: Daily (IFA), Tuesday and Thursday (ELISA)
Units: Titer
Range: Negative
Remarks: ANCA (Anti Neutrophil Cytoplasmic Antibody) testing has revolutionized the diagnosis and treatment of various autoimmune mediated vasculities. Both ANCA-C (Cytoplasmic) and ANCA-P (Peripheral) are clinically important and are used in the investigation of the pathologic triad of Wegeners granulomatosis (WG) which includes: granulomatous inflammation of the upper and lower respiratory tract, vasculitis and necrotizing glomerulonephritis.
Also ANCA test have proven to be quite important in the investigation of atypical or inflammatory bowel disease (IBD), ulcerative colitis and sclerosing cholangitis. ANCA-C (PR3 Anti Serine Protease 3 antibody) represents the most useful marker available for WG and its variants. PR3-ANCA is detected in systemic vasculitic disorders. PR3 is the classical autoantigen in Wegeners granulomatosis.
About 65% of patients in the initial phase of the disease are positive for PR3-ANCA. During active phases PR3 can be detected in more than 95% of patients. Reactivity with ANCA-P (MPO Myeloperoxidase antibody) includes subjects who have Churg-Strauss syndrome (an allergic granulomatosis), rheumatoid arthritis with or without vasculitis or Feltys syndrome, alveolar hemorrhage, angiItis/polyangiitis, vasculitis, capillaritis, leukocytoclastic skin vasculitis, necrotizing-crescentic glomerulonephritis, inflammatory bowel disease, autoimmune liver disease.
The occurrence of ANCA may be the result of prior transfusion or a pregnancy and may cause transfusion-related acute lung injury.
Important: PR3 and MPO ELISA methods cannot replace the standard IFA method with human neutrophils for detecting ANCA antibodies because there are too many other specificities that are clinically important. This is especially true in the case of atypical or inflammatory bowel disease (IBD), ulcerative colitis and sclerosing cholangitis.
