Is copper hepatotoxic in primary biliary cirrhosis?

In primary biliary cirrhosis (PBC) liver copper retention occurs as a complication of cholestasis. By analogy with Wilson's disease, it has been suggested that copper retention is hepatotoxic in PBC, and this has been the rationale for the use of D-penicillamine in this disease. The hypothesis that copper is hepatotoxic in PBC has not been tested and in this study we have evaluated the role of liver copper retention in the pathogenesis of PBC. Sixty-four patients with PBC have been studied. Fifty-four had increased liver copper concentrations. Liver cell synthetic function was well preserved. All the patients had normal prothrombin times, and only two had subnormal serum albumin concentrations. There was no correlation between liver copper concentrations and the degree of liver cell damage assessed biochemically (aspartate transaminase), and histologically. Electron microscopy was performed on liver biopsies from five patients with markedly increased liver copper concentrations. The liver cell ultrastructure was compatible with cholestasis. Liver cells contained electron dense lysosomes, which were shown to contain copper and sulphur by x-ray probe microanalysis. The characteristic organelle changes associated with copper toxicity in Wilson's disease were not observed. The biochemical, histological, and histochemical differences between PBC complicated by liver copper retention, and Wilson's disease, indicates that there are differences in the handling of copper in these disease. In this study we could find no evidence to suggest that copper plays an important role in the pathogenesis of liver dysfunction in PBC.