title: The association of complement activation at a low temperature with hepatitis C virus infection in comparison with cryoglobulin.
abstract: Complement activation at a low temperature in vitro and cryoglobulinaemia are associated with hepatitis C virus (HCV) infection. The frequency of HCV antibody positivity determined in serum specimens that showed the cold-dependent activation of complement was 100%, whereas it was 48% among sera with cryoglobulin. On the other hand, the frequency of cold activation among HCV-infected sera was 41%, and that of cryoglobulin 48%. Cold activation was not found in any HCV- sera studied, whereas cryoglobulin was found at a frequency of 14% in HCV- sera. Cold activation was also absent among hepatitis B virus (HBV) S antigen or antibody-positive sera, except a few that were both HBV+ and HCV+. Rheumatoid factor was also frequently detected in sera with cold activation or cryoglobulin. Cold activation and cryoglobulin may be generated by common mechanisms in which a low avidity, low temperature-preferring antibody may function. In sera with cold activation, fine particles of immune complexes, which do not form precipitates, may activate the complement system. HCV is a unique virus that coexists with antibody in the serum, therefore the avidity of the antibody for the virus antigen may be low, and occasionally react only at a low temperature. This may be why the in vitro phenomenon related to immune complexes occurs specifically in HCV-infected sera.
authors.affiliation: Central Clinical Laboratory, Osaka Medical College, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ueda
authors.forename: H
authors.initials: H
authors.lastname: Nakajima
authors.forename: T
authors.initials: T
authors.lastname: Nakagawa
authors.forename: A
authors.initials: A
authors.lastname: Shimizu
mesh_terms: D003080:Cold Temperature; D003167:Complement Activation; D003449:Cryoglobulinemia / Q000097:blood / Q000276:immunology*; D006510:Hepatitis B Antibodies / Q000097:blood; D006511:Hepatitis B Antigens / Q000097:blood; D006526:Hepatitis C / Q000097:blood / Q000276:immunology*; D006801:Humans; D012217:Rheumatoid Factor / Q000097:blood
chemical_list: D006510:Hepatitis B Antibodies; D006511:Hepatitis B Antigens; D012217:Rheumatoid Factor