ELEVATED RUBELLA ANTIBODIES IN PATIENTS WITH CHRONIC LIVER-DISEASE

Patients with autoimmune chronic active hepatitis (AICAH) and certain other chronic liver disorders often have very high titres of haemagglu tination-inhibition (HI) antibodies to rubella virus. In this study it is shown, using floatation centrifugation, that the high rubella HI r eactivity is not caused by nonspecific lipoprotein inhibitors but rath er by antibodies specific for the rubella haemagglutinin (E1 glycoprot ein). After sucrose density gradient ultracentrifugation of sera the m ajor HI reactivity was recovered in the IgG containing fractions. The IgG antibody fraction was strongly reactive by an indirect enzyme-link ed immunosorbent assay (ELISA). Higher prevalence and titres of rubell a antibodies were also demonstrated by the complement fixation (CF) te st using a haemagglutinin-free antigen, and by an indirect haemaggluti nation (IHA) test (Rubacell) using a cell-associated antigen which is distinct from the antigens used in the HI and CF tests. This high rube lla antibody response is therefore demonstrated using th ree distinct antigen-antibody systems. By means of absorption experiments and radio immunoprecipitation assays the coating antigen used in the IHA test wa s shown to reside in the E2 glycoprotein. The cause of this enhanced a ntibody response to rubella virus structural proteins remains elusive. (C) 1994 Wiley-Liss. Inc.