Acute hepatitis: significance of changes in complement components.

Serial measurements of complement components were performed in fifty-nine patients with acute, uncomplicated hepatitis and twelve with alcoholic cirrhosis. Thirty-one of the former group had detectable hepatitis B antigen. Abnormal complement profiles were observed in nine patients with hepatitis B and seven with antigen-negative hepatitis. Low levels of C4, C3 and factor B were common in the subjects with cirrhosis and confined to those cases with severe reduction in serum albumin and/or prothrombin index. By contrast, the complement changes in the patients with hepatitis occurred without significant alteration in these parameters; certain subjects also had reduction in C1q and C5 and a significant number had C3d detectable in fresh plasma. The pattern of abnormality suggests predominant involvement of the classical pathway and it is concluded that this results, at least in part, from an immune process evident only in the early clinical phase of hepatitis. Such gross changes in complement are likely to reflect immune-complex activity and it is proposed that these complexes may be important in the clearance of virus material. The data supports a previous suggestion that recovery from acute hepatitis is primarily dependent on host immune competence rather than viral cytotoxicity or generation of immune complexes.