Extrahepatic autoimmune features of HCV infection include autoantibody production and the development of mixed cryoglobulinemia. Anti-Clq antibody, detected with high frequency in systemic lupus erythematosus and hypocomplementemic urticarial vasculitis, may have a direct pathogenic role in complement mediated autoimmune diseases. In this study, we investigate the prevalence of anti-Clq antibody in a population of patients with chronic HCV infection.
Serum was obtained from a group of 50 patients with chronic HCV infection and control groups comprised of patients with SLE, rheumatoid arthritis (RA), scleroderma (PSS), Sjögren's syndrome (SS), mixed connective tissue disease (MCTD), and healthy individuals.
Anti-Clq antibody was detected in 38% of HCV patients compared with 2% of healthy controls (p < 0.0001). Levels were also significantly elevated in patients with SLE (61%), RA (20%), PSS (15%), SS (15%) and MCTD (15%).
In addition to numerous other autoantibodies, patients with chronic HCV infection exhibit increased production of anti-Clq IgG antibodies. This observation may have implications for the pathogenesis of the mixed cryoglobulinemic vasculitis syndrome.