What is the role of antibody deposition in the pathophysiology of vasculitis?

Updated: Dec 10, 2018
  • Author: Nadia Jennifer Chiara Luca, MD; Chief Editor: Lawrence K Jung, MD  more...
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Answer

Henoch-Schönlein purpura is generally characterized by the deposition of IgA antibodies in affected tissues. Histopathologically, the typical finding on skin biopsy is leukocytoclastic vasculitis, with perivascular accumulation of neutrophils and mononuclear cells. Immunofluorescence demonstrates IgA, C3, and fibrin in the walls of affected vessels, including the postcapillary venules within the dermis, and the endothelial and mesangial cells of the kidney. Elevated serum IgA and circulating IgA-containing immune complexes may be present in some patients. One study showed that galactose deficiency of O-linked glycans in the hinge region of IgA1 has been associated with Henoch-Schönlein purpura. [16]

In anti-GBM antibody disease, circulating antibodies bind to type IV collagen within the glomerular basement membrane. Immunofluorescence study of renal biopsies demonstrates linear deposition of IgG along the glomerular basement membrane. Pulmonary hemorrhage occurs when these antibodies have access to the alveolar basement membrane.


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