Perinuclear Anti-Neutrophil Cytoplasmic Antibodies or p-ANCA, are a type of antibody in the immune system that attaches to the negatively charged DNA in the nucleus of a cell. When stained with a fluorescent stain, the antibodies indicate the location of the nucleus as they surround it.
Although a key part of the immune system, they can be a component of several autoimmune diseases including ulcerative colitis, Churg-Strauss syndrome, primary sclerosing cholangitis, polyarteritis nodosa, microscopic polyangiitis, glomerulonephritis, rheumatoid arthritis, and vasculitis. However, although the presence of p-ANCA in higher than normal quantities can help confirm a diagnosis of these conditions, the absence of high levels does not rule them out.