Fulminating vasculitis in a homozygous C2-deficient patient1

Author and Disclosure Information


Homozygous C2 deficiency is associated with a variety of autoimmune diseases, but has never been described in association with acute necrotizing vasculitis. The authors observed such a case involving a 55-year-old white man who presented with a five-week history of progressive digital gangrene. There was no clinical or laboratory evidence of systemic lupus erythematosus or other connective tissue disease. Angiography supported the diagnosis of obliterative vasculitis involving arteries of both medium and small caliber. High levels of immune complexes were detected, documented by Clq binding and cryoprecipitation. Total hemolytic complement activity was undetectable. Assays of individual complement components revealed absence of C2. Evidence of participation of the complement system in mediation of vascular inflammation was supported by demonstration of C3 activation products using two-dimensional electrophoresis; in view of the normal C4 levels, this suggests activation of an alternate pathway. It would appear that acute complement-mediated vascular inflammation can occur in the absence of an early component of the standard pathway.