What is the Difference Between c-ANCA and p-ANCA

The key difference between c-ANCA and p-ANCA is that c-ANCA is an autoantibody that specifically binds to proteinase 3 antigen in the cytoplasm of neutrophils, while p-ANCA is an autoantibody that specifically binds to myeloperoxidase and bactericidal/permeability-increasing protein in the cytoplasm of neutrophils.

Antineutrophil cytoplasmic antibodies (ANCAs) are a group of autoantibodies against antigens in the cytoplasm of neutrophils and monocytes. They are mainly of IgG type and can be detected by blood tests. These autoantibodies are particularly associated with systemic vasculitis. Therefore, c-ANCA and p-ANCA are two different types of autoantibodies or antineutrophil cytoplasmic antibodies that act against antigens in the cytoplasm of neutrophils and monocytes.

CONTENTS

1. Overview and Key Difference
2. What is c-ANCA 
3. What is p-ANCA
4. Similarities Between c-ANCA and p-ANCA
5. c-ANCA vs. p-ANCA in Tabular Form
6. FAQ – c-ANCA and p-ANCA
7. Summary – c-ANCA vs. p-ANCA

What is c-ANCA?

c-ANCA is an antineutrophil cytoplasmic antibody. It is an autoantibody produced by the body that acts against one of its own proteins called proteinase 3 (PR3) in the cytoplasm of the neutrophils. PR3 is the most common antigen or protein target of ANCA in patients diagnosed with granulomatosis with polyangiitis. Granulomatosis with polyangiitis is a rare disorder that results in the inflammation of blood vessels in the nose, sinuses, throat, lungs, and kidneys. In active granulomatosis with polyangiitis, c-ANCA is normally found over 90% of the time.

c-ANCA shows a diffusely granular, cytoplasmic staining pattern under microscopy. This pattern is a result of the binding of c-ANCA to its target protein PR3. Furthermore, the c-ANCA test is a specific test that measures c-ANCA in the blood.

What is p-ANCA?

p-ANCA is a special class of anti-neutrophil cytoplasmic antibodies that bind to a specific protein around the nucleus of a neutrophil. p-ANCAs bind to myeloperoxidase (MPO), a neutrophil granule protein in the cytoplasm of neutrophils specifically. The primary role of this protein is to generate oxygen radicals in normal metabolic processes. Less commonly, it can also bind to antigens such as lactoferrin, elastase, and cathepsin G. p-ANCA denotes a staining pattern present in the perinuclear space of the cytoplasm.

p-ANCA test is a specific test that measures p-ANCA in the blood. Furthermore, p-ANCA is associated with several medical conditions such as ulcerative colitis, eosinophilic granulomatosis with polyangiitis, primary sclerosing cholangitis, microscopic polyangiitis, focal necrotizing and crescentic glomerulonephritis, and rheumatoid arthritis.

What are the Similarities Between c-ANCA and p-ANCA?

• c-ANCA and p-ANCA are two different types of autoantibodies or antineutrophil cytoplasmic antibodies that act against antigens in the cytoplasm of neutrophils and monocytes.
• Both are proteins in nature.
• They are associated with different autoimmune disorders.
• Specific blood tests can identify them.
• Both form specific patterns after binding to specific proteins in the cytoplasm of neutrophils.

What is the Difference Between c-ANCA and p-ANCA?

c-ANCA specifically binds to proteinase 3 antigen in the cytoplasm of neutrophils, while p-ANCA specifically binds to myeloperoxidase and bactericidal/permeability-increasing protein in the cytoplasm of neutrophils. Thus, this is the key difference between c-ANCA and p-ANCA. Furthermore, c-ANCA denotes a staining pattern present in diffuse coarse granular, centrally accentuated cytoplasm, while p-ANCA denotes a staining pattern present in the perinuclear space of the cytoplasm.

The infographic below presents the differences between c-ANCA and p-ANCA in tabular form for side-by-side comparison.

FAQ: c-ANCA and p-ANCA

What is the full meaning of p-ANCA?

P-ANCA stands for Perinuclear Anti-neutrophil Cytoplasmic Antibodies.

What is the full meaning of C-ANCA?

C-ANCA stands for Cytoplasmic Antineutrophil Cytoplasmic Autoantibody.

What is the treatment for C ANCA?

(c-ANCA)–positive vasculitis is usually treated with cyclophosphamide and corticosteroids.

Summary – c-ANCA vs. p-ANCA

Autoantibodies are antibodies that usually react with self-antigens. Antineutrophilic cytoplasmic antibodies (ANCA) are a type of autoantibodies associated with a heterogeneous group of rare autoimmune conditions that cause inflammation of blood vessels. c-ANCA and p-ANCA are two different types of autoantibodies or antineutrophil cytoplasmic antibodies that act against antigens in the cytoplasm of neutrophils and monocytes. c-ANCA acts against one of its own proteins called proteinase 3 (PR3) in the cytoplasm of the neutrophils, while p-ANCA acts against its own proteins called myeloperoxidase (MPO), lactoferrin, elastase, and cathepsin G in the cytoplasm of the neutrophils. So, this summarizes the difference between c-ANCA and p-ANCA.

Reference:

1. “ANCA – Overview.” Science Direct.
2. Yamamoto-Furusho, Jesus K, et al. “Perinuclear Anti-Neutrophil Cytoplasmic Antibodies (P-ANCA) in Chronic Ulcerative Colitis: Experience in a Mexican Institution.” World Journal of Gastroenterology, U.S. National Library of Medicine.

Image Courtesy:

1. “C ANCA” By Simon Caulton – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “P ANCA” By Simon Caulton – Own work (CC BY-SA 3.0) via Commons Wikimedia