Antibodies to the cytoplasm of neutrophils in the blood
Last reviewed: 23.04.2024
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In the norm there are no antibodies to the cytoplasm of neutrophils in the blood serum.
Antibodies to the cytoplasm of neutrophils (ANCA) - a complex of antibodies specific for various granulocyte, monocytic and, possibly, endothelial cytoplasmic antigen.
When determining the ANCA using the indirect immunofluorescence method using neutrophils of healthy donors, two different types of fluorescence can be identified - classical diffuse (k-ANCA) and perinuclear (p-ANCA). These types of fluorescence are caused by a different antigenic orientation of ANCA. Antibodies in classical diffuse fluorescence are in most cases directed against protein kinase-3 and the bactericidal action enhancing protein of neutrophils. In Wegener's granulomatosis, k-ANCA in serum is detected in 88-95% of patients. This is a highly specific sign of Wegener's granulomatosis. The diagnostic sensitivity of the method is 90%, the specificity is more than 95%. The titer of k-ANCA rises in a few weeks or months before the disease worsens and decreases when remission is achieved. Detection of k-ANCA in the blood is a direct indication for immunosuppressive therapy.
P-ANCA are directed against a wide range of cytoplasmic antigens: myeloperoxidase, elastase, lactoferrin, cathepsin G and other polypeptides. Most often, p-ANCA is detected with primary sclerosing cholangitis (60-85% of patients), ulcerative colitis (60-75%), chronic autoimmune active hepatitis (60-70%), primary biliary cirrhosis (in 30-40 %), Crohn's disease (in 10-20% of patients).
In patients with primary sclerosing cholangitis, the presence of p-ANCA does not correlate with the clinical activity of liver damage.
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