Autoantibody Profile of Adult Patients With Childhood Onset Type 2 Autoimmune Hepatitis

Background Anti‐liver kidney microsome (anti‐LKM) autoantibodies are a distinguishing feature of type II autoimmune hepatitis (AIH‐2). However, the levels of anti‐LKM‐1 in adult AIH‐2 patients and their role in liver immunopathology remain equivocal. The aim of the study was to survey the autoantibody profile and the activity of liver disease in adult patients diagnosed with AIH‐2 at childhood. Methods The autoantibody profile of adults was compared with the autoantibodies of the pediatric period. Liver function test, Immunoglobulin G (IgG), and gamma globulins were evaluated at the AIH presentation, at the age of 18 years, and at the current adult visit. Results All ten patients tested positive for LKM‐1 at least once during the pediatric period. At the adult visit, four patients lost autoantibody positivity. LKM‐1 was positive in four, liver cytosol antigen 1 (LC‐1) in two, soluble liver antigen in one, and antinuclear antigen in one patient. Additionally three patients with LKM‐1 and one patient without LKM‐1 were positive for AMA‐M2 (where AMA is antimitochondrial antibodies) Immunoglobulin M (IgM). Liver function markedly improved at 18 years and adult visit compared with initial diagnosis of AIH with only a mild decrease of IgG. The six adult patients positive for at least one autoantibody had statistically lower aspartate aminotransferase (AST) and gamma‐glutamyltranspeptidase (GGTP) than the four patients autoantibody negative (AST: 52 vs. 88 IU/l, P < 0.05; GGTP 19 vs. 163 IU/l, P < 0.05). Conclusion LKM‐1 positivity is not a stable condition in all patients with AIH‐2. Patients who remained autoantibody positive had better liver function tests than those who lost their positivity. The presence of AMA‐M2 autoantibodies suggest that development of AIH/Primary Biliary Cirrhosis (PBC) overlap syndrome should be considered.