Immunodiagnosis of Systemic Vasculitis

Vasculitis is a general term for inflammation of the blood vessels. Upon clinical suspicion of systemic vasculitis, therefore, it is important to test for infectious serology, including hepatitis B/C virus or human immunodeficiency virus (HIV), and autoimmune serology, including rheumatoid arthritis and systemic lupus erythematosus. The small vessel vasculitides are subdivided into anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and immune complex small-vessel vasculitis. Even before ANCA were established to be pathogenic, ANCA testing was performed for follow-up of AAV patients. Anti-glomerular basement membrane (GBM) disease is a mimic of AAV because this disease presents with rapidly progressive glomerulonephritis and/or pulmonary hemorrhage. According to the Chapel Hill Consensus Conference, anti-GBM disease has been defined as vasculitis affecting glomerular capillaries, pulmonary capillaries, or both, with GBM deposition of anti-GBM autoantibodies.