C-ANCA
Encyclopedia
Anti-neutrophil cytoplasmic antibody
Anti-neutrophil cytoplasmic antibodies are a group of autoantibodies, mainly of the IgG type, against antigens in the cytoplasm of neutrophil granulocytes and monocytes...
, are a type of autoantibody
Autoantibody
An autoantibody is an antibody manufactured by the immune system that is directed against one or more of the individual's own proteins. It is derived from the Greek "auto" which means "self", "anti" which means "against" and "body"...
, an antibody
Antibody
An antibody, also known as an immunoglobulin, is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, termed an antigen...
produced by the body that acts against one of its own proteins. These antibodies show a diffusely granular, cytoplasmic staining pattern under microscopy
Microscope
A microscope is an instrument used to see objects that are too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy...
. This pattern results from binding of ANCAs to antigen
Antigen
An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...
targets throughout the neutrophil cytoplasm
Cytoplasm
The cytoplasm is a small gel-like substance residing between the cell membrane holding all the cell's internal sub-structures , except for the nucleus. All the contents of the cells of prokaryote organisms are contained within the cytoplasm...
, the most common protein target being proteinase 3
Proteinase 3
Proteinase 3 also known as PRTN3 is an enzyme which 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 unknown but in human neutrophils proteinase 3 contributes to the...
(PR3). For example, PR3 is the most common antigen target of ANCA in patients with Wegener's granulomatosis
Wegener's granulomatosis
Wegener's granulomatosis , more recently granulomatosis with polyangiitis , is an incurable form of vasculitis that affects the nose, lungs, kidneys and other organs. Due to its end-organ damage, it is life-threatening and requires long-term immunosuppression...
. In active Wegener's, c-ANCA is found in over 90% of the time. Other antigens may also occasionally result in a c-ANCA pattern.