NONMUSCLE MYOSIN AS TARGET ANTIGEN FOR HUMAN AUTOANTIBODIES IN PATIENTS WITH HEPATITIS-C VIRUS-ASSOCIATED CHRONIC LIVER-DISEASES

Three patients with hepatitis C virus (HCV)-related chronic liver dise ase were shown to have autoantibodies strongly reacting with cytoskele tal fibres of non-muscle cells. The heavy chain of non-muscle myosin m icrofilament was the main target for those autoantibodies, as determin ed by (i) cell and tissue immunofluorescence studies showing colocaliz ation with an anti-myosin antibody prototype; (ii) primary reactivity in immunoblotting with a 200-kD protein, using either MOLT-4 cells, hu man platelets, or affinity-purified non-muscle myosin as antigen extra ct; and (iii) immunoblotting of similar immunoreactive fragments in pa pain-digested MOLT-4 cell extracts, by using those human sera and anti body prototype. Autoantibodies to non-muscle myosin heavy chain were n ot previously reported in patients with chronic liver diseases, especi ally in those associated with HCV infection.