Anti-proteinase 3 antibody positivity

What it means

The presence of autoantibodies in the blood circulation that react against proteinase 3. Proteinase 3 (PR3) antigen is a 29-kD serine protease that exists as a protein triplet in human neutrophils

PR3 directed c-ANCA antibodies are present in 80-90% of granulomatosis with polyangiitis, 20-40% of microscopic polyangiitis, 20-40% of pauci-immune crescentic glomerulonephritis and 35% of eosinophilic granulomatosis with polyangiitis.

Rare diseases that can present with this3

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Anti-PR3 antibody positivity