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

Abstract

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. 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. 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. 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.