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Antibodies to neutrophil cytoplasm in blood
Last reviewed: 05.07.2025
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Normally, antibodies to neutrophil cytoplasm are absent in the blood serum.
Anti-neutrophil cytoplasmic antibodies (ANCA) are a complex of antibodies specific to various granulocyte, monocytic and, possibly, endothelial cytoplasmic antigens.
When determining ANCA by the indirect immunofluorescence method using neutrophils from healthy donors, two different types of fluorescence can be detected - classical diffuse (c-ANCA) and perinuclear (p-ANCA). These types of fluorescence are due to different antigenic orientations of ANCA. Antibodies in classical diffuse fluorescence are in most cases directed against protein kinase-3 and the neutrophil protein that enhances the bactericidal action. In Wegener's granulomatosis, c-ANCA is detected in the blood serum 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 c-ANCA titer increases several weeks or months before the exacerbation of the disease and decreases when remission is achieved. Detection of c-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 in primary sclerosing cholangitis (in 60-85% of patients), nonspecific ulcerative colitis (in 60-75%), chronic autoimmune active hepatitis (in 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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