Prognostic relevance of serum inhibitory factors (SIF) in protracted and persistent hepatitis B.

In a follow-up study of 3 years' duration, serum inhibitory factors (SIF) were analysed in 23 patients with a protracted course of viral hepatitis B (PVH) and 12 patients with chronic persistent hepatitis (CPH). Four patients showed a progressive course, developing chronic active hepatitis, and one died of liver failure. All 4 patients had high and persisting SIF activity. The other patients were either SIF negative or lost SIF during the observation period. The inhibitory moiety was isolated from an albumin-rich serum fraction, indicating that the factor was of the same nature as previously described in patients with acute viral hepatitis B. SIF was also demonstrated in other viral infections but was absent or of low activity in autoimmune, toxic or nutritive disorders. These results suggest that SIF may act as an immunoregulatory molecule protecting the liver from exaggerated immune response.