Clinical significance of autoantibody to hepatocyte membrane antigen in type 1 autoimmune hepatitis

Abstract

OBJECTIVE: By using HepG2 as flow cytometry target, we have reported that autoantibody to hepatocyte membrane antigen (anti-HMA) was frequently found in autoimmune hepatitis (AIH) patients. In this study, we have examined this autoantibody in relation to clinical features in these patients. METHODS: HepG2 cells were incubated with diluted serum and subsequently with FITC-conjugated antihuman immunoglobulin. The results were expressed as relative fluorescence intensity. The prevalence of anti-HMA was estimated by setting the upper limit of mean ± 3 SD obtained from healthy subjects. RESULTS: We found that the mean relative fluorescence intensity was 1.67 ± 0.5 in AIH with low serum ALT level (group 1 AIH), 4.20 ± 1.9 in AIH with high serum ALT level (group 2 AIH), and 1.92 ± 0.9 in age-matched chronic hepatitis C virus-positive patients. Their positive rate was 37.5% (three of eight) in group 1 AIH, 95.0% (19 of 20) in group 2 AIH, and 33.3% (four of 12) in chronic hepatitis C patients. In 12 group 2 AIH patients, their mean relative fluorescence intensity was significantly decreased during immunosuppressive therapy. The association between serum ALT level and anti-HMA was confirmed by the facts that a significant direct quantitative relationship existed between these two levels and by serial studies of anti-HMA in four AIH patients. Anti-HMA was also detected in five non-B, non-C hepatitis patients having clinical features resembling those of AIH. CONCLUSIONS: The present results have shown that the anti-HMA was tightly associated with the degree of hepatocyte inflammation and that the measurement of anti-HMA may have some advantage in clinical evaluation of some of non-B, non-C hepatitis patients.