Aspartate aminotransferase-immunoglobulin complexes in patients with chronic liver disease.

AIM: To determine the complex of AST and immunoglobulin and to investigate its clinical significance in patients with liver disease. METHODS: The complex of AST and immunoglobulin was determined by encounter immunoelectrophoresis and its clinical significance was investigated in 128 patients with liver disease. RESULTS: AST was bound to immunoglobulin of anti-immunoglobulin A (IgA) class, but any binding to anti-immunoglobulin G and anti-immunoglobulin M classes was not observed. Although the incidence of AST-immunoglobulin complex was 41.8% in chronic hepatitis (CH), the incidences in liver cirrhosis and hepatocellular carcinoma were 62.2 and 90.0%, respectively. In alcoholic liver disease with high level of serum IgA, the incidence of the complex was 66.7%, which was higher than that in CH. The ratio of binding to lambda-chain of IgA was higher than that to kappa-chain of IgA. The serum level of IgA and the ratio of AST/alanine aminotransferase (ALT) were significantly higher in patients with AST-IgA complex than in those without complex. CONCLUSION: These results suggest that AST-IgA complex in patients with progressive liver diseases and alcoholic liver injury can lead to elevation of the ratio of AST/ALT.