What Causes Vasculitis?

Vasculitis refers to a group of disorders characterized by inflammation and damage to blood vessel walls. The underlying cause is typically an abnormal immune response in which the body’s immune system mistakenly attacks its own blood vessels. This autoimmune reaction can be triggered by various factors, including infections (such as hepatitis B or C virus, HIV, or bacterial endocarditis), certain medications (e.g., propylthiouracil, hydralazine, or allopurinol), or exposure to environmental agents like silica dust. In some cases, vasculitis occurs secondary to other systemic autoimmune diseases—such as rheumatoid arthritis, systemic lupus erythematosus, or Sjögren’s syndrome. Genetic predisposition may also play a role, particularly in conditions like granulomatosis with polyangiitis or eosinophilic granulomatosis with polyangiitis, where specific HLA alleles have been associated with increased susceptibility. However, in many instances, no definitive trigger is identified, and the condition is classified as idiopathic.