ANCA : Antineutrophil Cytoplasmic Antibodies test


🏾 Content :


🏾 Why the ANCA blood test is performed ?

ANCA detection is a well-established diagnostic test for the evaluation of patients suspected of having AAV and certain inflammatory bowel diseases.

Autoimmune vasculitides cause inflammation and swelling of small blood vessels. These tiny blood vessels are found all over the human body, so any part of the body can be affected, but most commonly the kidneys, lungs, joints, ears, nose, and nerves.

Organs Symptoms
General symptoms Fever, Fatigue, Weightloss, Muscle and/or joint pain.
The eyes Redness, Blurred vision, Loss of vision.
The ears Ringing in the ears (tinnitus), Hearing loss.
The sinuses Sinus pain, Runny nose, Nosebleeds.
The skin Rashes, Wounds or ulcers, a type of deep wound that is slow to heal and/or keeps coming back.
The lungs Cough, Difficulty breathing, Chest pain.
The kidneys Blood in the urine, Foamy urine, which is caused by protein in the urine

Each type of ANCA affects different blood vessels and parts of the body. Types of autoimmune vasculitis include:



🏾 Blood sample for ANCA test

ANCAs are detected using a simple blood sample. There are no special preparations to make before the analysis and does not require fasting, unless your blood sample will be used for additional testing.

🏾 ANCA test

Indirect immunofluorescence (IFI) and enzyme immunoassay (ELISA) are the most commonly used techniques for detecting ANCA.

Indirect immunofluorescence (IFI)

uses ethanol-fixed neutrophils on a slide (5 minutes at +4 ◦C with ethanol 96-99%). The serum from your blood sample is mixed with the neutrophils on the slide and all the ANCAs in the sample attach to the neutrophil proteins. Treatment of the slide with a fluorochrome-stained antibody reacts with any ANCA present.

The two most common major immunostaining patterns are designated by the acronyms C-ANCA and P-ANCA:

p-anca

P-ANCA: it appears as an intense marking of the periphery nuclear lobes with an almost negative center, conferring a “cauliflower” image.

c-anca

C-ANCA: it corresponds to diffuse granular cytoplasmic fluorescence with, most often, reinforcement between the lobes of the core.

Note:
- A third aspect, described last and which is the most debated, is called atypical (aANCA), and combines characteristics of first two - If an ANCA test result is positive, an additional step may be taken to determine the amount of antibodies present. This is called a title

ELISA

The typing of the two main specificities (myeloperoxidase and proteinase 3) will be done by ELISA. This type of test helps identify the targeted protein in neutrophils.


🏾 Results interpretation

◾ ANCA test results should be interpreted with caution considering several factors. Your doctor will review your signs and symptoms in addition to the results of lab tests and other types of tests, such as imaging studies

Status % of patients with cANCA profile (PR3 antibodies) % of patients with pANCA profile (MPO antibodies)
Granulomatosis with polyangiitis (Wegener's granulomatosis) 90% with active disease, 60-70% without active disease Less than 10%
Microscopic polyangiitis 30% 60%
Eosinophilic granulomatosis with polyangiitis (Churg Strauss syndrome) Rare 50-80%
Polyarteritis nodosa Rare Rare

ANCA levels can change over time and can sometimes be used generally to monitor disease activity and/or response to treatment.

◾ In case of suspected inflammatory bowel disease (IBD):


🏾 What other tests could I have with this test?

Additional tests that may be performed to aid in diagnosis: erythrocyte sedimentation rate (ESR), CRP, Complete blood count (CNF), Blood urea nitrogen (BUN) concentration and creatinine to assess kidney function...

🏾 Frequently Asked Questions

Q: In which laboratories carry out ANCA research?

A: ANCA tests require specialized equipment and careful interpretation by trained professionals. Results may take several days to a week.


Q: How to differentiate between true pANCA antibodies from possible interference with antinuclear antibodies (ANA)?

A: Sera from positive patients with perinuclear or nuclear patterns are replicated using a formalin-fixed substrate, as well as methanol, to differentiate them


Q: Will anti-neutrophil cytoplasmic antibodies (ANCA) ever disappear?

A: Like other autoimmune diseases, levels can fluctuate, but once you develop an autoantibody, you will continue to have it.


Q: What are the different fixers used?

R: Ethanol, Formalin, Methanol



Reference

  1. W Pollock - Immunofluorescent patterns produced by antineutrophil cytoplasmic antibodies (ANCA)
  2. Autoanticorps anticytoplasme des polynucléaires neutrophiles (ANCA) : cibles antigéniques, méthodes diagnostiques
  3. NIH - Antineutrophil Cytoplasmic Antibodies (ANCA) Test
  4. Addendum to the International Consensus Statement on testing and reporting of antineutrophil cytoplasmic antibodies.
  5. TEST - Anticorps cytoplasmiques antineutrophiles (ANCA, MPO, PR3)
  6. Antineutrophil cytoplasmic antibody (ANCA), Wegener’s Granulomatosis
  7. 2021 American College of Rheumatology/Vasculitis Foundation Guideline for the Management of Antineutrophil Cytoplasmic Antibody–Associated Vasculitis
  8. Gary L. Horowitz - Autoantibodies: Methods and Meaning
  9. biominis - AC ANTI-CYTOPLASME DES POLYNUCLEAIRES NEUTROPHILES - ANCA
  10. Fokko J - Taking anti-neutrophil cytoplasmic antibody (ANCA) testing beyond the limits
  11. MCL - Test Definition: ANCA
  12. C. Beauvillain - Autoanticorps anticytoplasme des polynucléaires neutrophiles (ANCA) : cibles antigéniques, méthodes diagnostiques
  13. Sylvain Dubucquoi - Recherche d’ANCA au laboratoire en pratique quotidienne