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Autoimmune vasculitis diseases are characterized by abnormal immune responses that result in inflammation and necrosis of blood vessels. The immune dysfunction may be triggered by infection, autoimmune disease, or exposure to a drug; often the cause is unknown. ANCA-associated vasculitis diseases are often characterized by the size of the blood vessels involved. The diseases present with diverse clinical features and are often rapidly progressive, causing irreversible injury to the vessels of the organs affected, such as the kidneys and lungs.

Goodpasture's Syndrome, first described by Ernest Goodpasture in 1919, is characterized today by the triad of diffuse lung hemorrhage, proliferative nephritis and the presence of anti-GBM autoantibodies, which are present as linear deposits along the glomerular and alveolar basement membranes, and as circulating antibodies.

A negative result for PR3 ANCA diminishes the likelihood that a patient has active WG; but, approximately 20% of patients with limited WG may test negative for PR3 ANCA. The levels of PR3 ANCA often decline following successful treatment of patients with WG. Nevertheless, follow-up testing for PR3 ANCA to evaluate clinical status in treated patients should be used with caution as the levels of antibodies may correlate poorly with clinical status in some patients.

What does it mean if your PROTEINASE-3 ANTIBODY result is too high?

Proteinase 3 (PR3) antigen is a 29-kD serine protease that exists as a protein triplet in human neutrophils.

Wegener granulomatosis (WG) is an autoimmune vasculitis that affects the kidneys and lungs, as well as other organs. Patients with WG develop autoantibodies to the PR3 antigen of myeloid lysosomes (PR3 antineutrophil cytoplasmic antibodies [PR3 ANCA]).

Since it is often impossible to distinguish between WG and other forms of vasculitis on the basis of clinical signs and symptoms, tests for PR3 ANCA should be employed with other serologic tests in the initial diagnostic evaluation of patients with clinical features of vasculitis (eg, VASC / Antineutrophil Cytoplasmic Antibodies Vasculitis Panel, Serum).


Proteinase 3 antineutrophil cytoplasmic antibodies (PR3 ANCA) are detectable in nearly all patients with severe active Wegener granulomatosis (WG). The presence of PR3 ANCA is a specific diagnostic indicator of WG; less than 2% of positive results occur in patients who do not have the disease.

While the presence of proteinase 3 antineutrophil cytoplasmic antibodies (PR3 ANCA) is highly specific for Wegener granulomatosis (WG), it is recommended that positive test results obtained by immunoassay be confirmed by another testing method. This is best accomplished by testing for cytoplasmic ANCA (cANCA) and perinuclear ANCA (pANCA) by indirect immunofluorescence microscopy (ANCA / Cytoplasmic Neutrophil Antibodies, Serum). Alternately, VASC / Antineutrophil Cytoplasmic Antibodies Vasculitis Panel, Serum includes tests for PR3 ANCA, myeloperoxidase antibodies, and, if indicated, cANCA and pANCA. This panel is recommended for the initial diagnostic evaluation of patients clinically suspected of having systemic vasculitis. The simultaneous presence of PR3 ANCA and cANCA has a specificity greater than 99% for WG.

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