Anti-C1q IgG autoantibodies

Pathogenic autoantibody

Expression
Elevated (90-100% of patients)
Evidence level
established

Role in pathogenesis

IgG autoantibodies that bind the collagen-like region of C1q via their F(ab')2 fragments. Present in 90-100% of HUVS patients. Unlike SLE anti-C1q antibodies, HUVS antibodies can bind reduced/denatured C1q. Drive complement activation and immune complex deposition in vessel walls.

Sources (4)

DetailsWisnieski JJ et al. (1989) Serum IgG antibodies to C1q in hypocomplementemic urticarial vasculitis syndrome · Arthritis RheumPubMed
DetailsWisnieski JJ et al. (1992) Comparison of autoantibodies to the collagen-like region of C1q in hypocomplementemic urticarial vasculitis syndrome and systemic lupus erythematosus · J ImmunolPubMed
DetailsWisnieski JJ et al. (1992) IgG autoantibody to the collagen-like region of C1q in hypocomplementemic urticarial vasculitis syndrome, systemic lupus erythematosus, and 6 other musculoskeletal or rheumatic diseases · J RheumatolPubMed
DetailsMarzano AV et al. (2022) Urticarial vasculitis: Clinical and laboratory findings with a particular emphasis on differential diagnosis · J Allergy Clin ImmunolDOI