c-ANCAs, or PR3-ANCA, or

antineutrophil cytoplasmic antibodies Anti-neutrophil cytoplasmic antibodies (ANCAs) are a group of autoantibodies, mainly of the IgG type, against antigens in the cytoplasm of neutrophils (the most common type of white blood cell) and monocytes. They are detected as a blood test i ...

, are a type of

autoantibody An autoantibody is an antibody (a type of protein) produced by the immune system that is directed against one or more of the individual's own proteins. Many autoimmune diseases (notably lupus erythematosus) are associated with such antibodies. Pr ...

, an

antibody An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...

produced by the body that acts against one of its own proteins. These antibodies show a diffusely granular, cytoplasmic staining pattern under

microscopy Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of micr ...

. This pattern results from binding of ANCAs to

antigen In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. ...

targets throughout the

neutrophil Neutrophils (also known as neutrocytes or heterophils) are the most abundant type of granulocytes and make up 40% to 70% of all white blood cells in humans. They form an essential part of the innate immune system, with their functions varying in ...

cytoplasm In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The ...

, the most common protein target being

proteinase 3 Proteinase 3, also known as PRTN3, is an enzyme that in humans is encoded by the ''PRTN3'' gene. Function PRTN3 is a serine protease enzyme expressed mainly in neutrophil granulocytes. Its exact role in the function of the neutrophil is unknow ...

(PR3). For example, PR3 is the most common antigen target of ANCA in patients with

granulomatosis with polyangiitis Granulomatosis with polyangiitis (GPA), previously known as Wegener's granulomatosis (WG), is a rare long-term systemic disorder that involves the formation of granulomas and inflammation of blood vessels (vasculitis). It is a form of vasculitis ...

. In active granulomatosis with polyangiitis, c-ANCA is found over 90% of the time. Other antigens may also occasionally result in a c-ANCA pattern.

References

{{Systemic vasculitis Autoantibodies

See also

References