Preferred Sample Type
Suitable Specimen Types
- Serum
Specimen Transport
.Sample Processing in Laboratory
Usual
Sample Preparation
Usual
.Turnaround Time
4 DaysSample Stability
Stored at 4oC
.Neutrophil Cytoplasmic Antibody (ANCA)
General Information
Some indications: Screening test for small vessel vasculitis. Seen particularly in Wegener's granulomatosis (WG), microscopic polyangitis (MPA) and its renal limited variant (pauci-immune crescentic glomerulonephritis) and Churg-Strauss syndrome If this test is required urgently please contact the Duty Immunologist via bleep 2119 during the normal working hours of the laboratory ( Mon - Fri 09.00 to 17.00)
Patient Preparation
None
Notes
There are two major subclasses of ANCA, characterised by staining patterns found when using fixed human neutrophils as substrate under Indirect Immunofluorescence (IIF): 1. C-ANCA (Cytoplasmic or Classical Staining ANCA), denotes a granular cytoplasmic staining pattern on ethanol fixed neutrophils, with some interlobular accentuation. C-ANCA are principally directed against a 29,000 Dalton serine protease, proteinase 3 (PR3) present in the azurophil granules in the cytoplasm of human neutrophils. Other C-ANCA specificities have been detected for cationic protein 57 (CAP57) and cathepsin G. C-ANCA positive is suggestive but not diagnostic of WG, MPA (and its renal limited variant) and Churg-Strauss. C-ANCA positive results must be followed up by ELISA tests for anti-MPO and anti-PR3. 2. P-ANCA (Perinuclear Staining ANCA), denotes a staining pattern present in the perinuclear space of the cytoplasm of ethanol fixed neutrophils. P-ANCA are principally directed against myeloperoxidase (MPO), which is also found in azurophil granules in the cytoplasm of human neutrophils. Other P-ANCA antigen specificities are for elastase and lactoferrin. P-ANCA is associated in MPA and in some cases of WG and Churg-Strauss syndrome although can also be seen in inflammatory bowel disease and other autoimmune diseases. P -ANCA positive results must be followed up by ELISA tests for anti-MPO and anti-PR3. ANCA measurements are not closely associated with disease activity and should therefore not determine treatment increases or decreases. However treatment withdrawal in patients with a persistently positive ANCA is associated with relapse. Different ANCA patterns can be reported on the same sample in different laboratories due to variations in neutrophil substrate.
Reference Range
Negative
Specifications
- EQA Scheme?: Yes
-
EQA Status:
UK NEQAS eqa scheme for ANCA and GBM serology.