Anti-neutrophil cytoplasmic antibody

They are detected as a blood test in a number of autoimmune disorders, but are particularly associated with systemic vasculitis, so called ANCA-associated vasculitides (AAV).

p-ANCA antigens include myeloperoxidase (MPO) and bacterial permeability increasing factor Bactericidal/permeability-increasing protein (BPI).

Atypical ANCA are thought to be antigens similar to that of the p-ANCAs, however may occur due to differences in neutrophil processing.

[4] Microbial superantigens are molecules expressed by bacteria and other microorganisms that have the power to stimulate a strong immune response by activation of T-cells.

These molecules generally have regions that resemble self-antigens that promote a residual autoimmune response – this is the theory of molecular mimicry.

Atypical ANCA is associated with drug-induced systemic vasculitis, inflammatory bowel disease and rheumatoid arthritis.

Aberrant glycosylation of the MPO and PR3 specific ANCA enhances their ability to interact with activating Fc receptors on neutrophils.

This releases free oxygen radicals and lytic enzymes, resulting in damage to the endothelium via the induction of necrosis and apoptosis.

Animal models have shown that MPO antibodies can induce necrotizing crescentic glomerulonephritis and systemic small vessel vasculitis.

In these animal models the formation of glomerulonephritis and vasculitis can occur in the absence of T-cells, however neutrophils must be present.

Avacopan was approved for medical use in the United States to treat anti-neutrophil cytoplasmic autoantibody-associated vasculitis in October 2021.

[17][21] The Second International ANCA Workshop, held in The Netherlands in May 1989, fixed the nomenclature on perinuclear vs. cytoplasmic patterns, and the antigens MPO and PR3 were discovered in 1988 and 1989, respectively.