There are three types of antibodies
which target the neutrophils (cANCA, pANCA and atypical ANCA) and can be performed on an urgent basis for patients
with suspected autoimmune disorder such as vasculitis and also on a routine basis for follow up of
diagnosed patients.
Initially screening is performed on ethanol fixed
neutrophils at a serum dilution of 1:25. The binding of the antibody is
visualised by fluorescent anti-IgG. The positive serum is then
subjected to an ELISA technique which is used to quantitative the level
of myeloperoxidase (MPO; dominant pANCA autoantigen) and proteinase-3
(PR-3; dominant cANCA ).
Cytoplasmic pattern (cANCA)
Nucleus
Description
Image:
Disease:
Antigen:
Granular staining of the cytoplasm of
neutrophils.
Wegener's Granulomatosis (90%)
A 29
kDa antigen known as proteinase 3 (PR3)
Perinuclear pattern (pANCA)
Nucleus
Description
Image:
Disease:
Antigen:
Homogenous perinuclear staining due to an
artefact of the fixative. This causes the redistribution of the antigen
from the cytoplasm to the perinuclear position. Formalin reverts the
pANCA to cANCA.
