Low temperature dependent IgG3 subclass antibody with low avidity to C100-3 antigen derived from hepatitis C virus in...

The presence of an antibody which reacts strongly at lower temperatures to C100-3 antigen derived from the hepatitis C virus (HCV) was demonstrated in blood donors' sera. These sera reacted with the antigen most strongly at 4 C and most weakly at 37 C and are termed 'cold antibody group'. The cold antibody group reaction was specifically inhibited with soluble C100-3 antigen. Cold antibody bound to C100-3 antigen at 4 C was dissociated at 37 C and was isolated in this manner. Low temperature-dependent anti C100-3 antibody was shown to be predominantly IgG3 subclass by ELISA using anti-human IgG subclass antibody. This IgG3 antibody was dissociated from antigen with 6M urea, demonstrating its low avidity. HCV-RNA was demonstrated in two of five samples. Therefore, to achieve more effective prevention of post-transfusion hepatitis C, we propose the incorporation of programs to detect low temperature-dependent low-avidity antibody against HCV-related antigen.