Anca - Altmeyers Encyclopedia - Department Internal medicine

Synonym(s)

Antineutrophil cytoplasmatic antibodies"; Anti-Neutrophil Cytoplasmic Antibodies; Antineutrophilic cytoplasmic antibodies; Cytoplasmic antibodies antineutrophilic

Definition
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ANCA is an acronym for "antineutrophil cytoplasmatic antibodies", a collective term for cytoplasmic(lysosomal) antigens in neutrophil granulocytes. Cytoplasmatic antigens (cANCA) and perinuclear antigens (pANCA; e.g. myeloperoxidase) are distinguished on the basis of the fluorescence pattern and localisation within the cell.

General information
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According to the pattern produced by indirect immunofluorescence on human leukocytes can be divided as follows:

cANCA (cytoplasmic ANCA; PR3-ANCA): directed against proteinase-3 (e.g. in granulomatosis with polyangiitis=Wegener-Grnaulomatosis)
pANCA (perinuclear ANCA; MPO-ANCA): directed against peroxidases of myeloid cells (see below Churg-Strauss syndrome, microscopic polyangiitis). Optional for ulcerative colitis, Crohn's disease.
xANCA (atypical ANCA): Against elastase, lactoferrin, lysozyme, cathepsin G (autoimmune liver diseases, chronic inflammatory bowel diseases).

Standard value: The reference range is not detectable

Pathologically increased: Crohn's disease and ulcerative colitis, rheumatoid arthritis, systemic lupus, Churg-Strauss syndrome, microscopic panarteritis, Wegener's granulomatosis, vasculitis of medium and large vessels.

Implementation
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Test material: Serum.

Determination method:

Indirect IFT: on ethanol-fixed granulocytes
ELISA with purified antigen: cANCA →neutrale Proteinase 3 (PR3-ANCA); pANCA → Myeloperoxidase

Note(s)
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The cANCA have a pathogenetic significance in that, after binding of the antibody to granulocytes, they induce a cascade of immunological processes which finally lead to cytokine release, endothelial activation and lymphocytic infiltration of the small vessels with consecutive vasculitis.