Pediatric and adult forms of type I autoimmune hepatitis in Argentina: evidence for differential genetic predisposition.

The aim of this study was to compare major histocompatibility complex (MHC) class II susceptibility to type 1 autoimmune hepatitis (AH) between children and adults of the same ethnic group. HLA-DRB1, HLA-DRB3, HLA-DQA1, and HLA-DQB1 gene subtypes were examined by high resolution oligonucleotide typing in 122 pediatric (PAH) and 84 adult (AAH) patients and in 208 controls. In children, HLA-DRB1*1301 was the primary susceptibility allele (66.4% patients vs. 10.6% controls, relative risk [RR] = 16.3, Pc < 10(-24)) whereas HLA-DRB1*1302, which differs from HLA-DRB1*1301 by only 1 amino acid, appeared to be protective. The exclusion of individuals with HLA-DRB1*1301 from control and pediatric patients allowed us to find a secondary association of PAH with HLA-DRB1*0301. Possession of HLA-DRB1*1301, however, was associated with a lower therapeutic response rate. Analysis of peptide binding pocket residues indicated that Tyr 10, Ser 11, Ser 13, and Val 86 in the class II beta chain were present in 85% of patients compared with 37% of controls, suggesting that a high proportion of AH susceptibility is attributable to these residues (etiologic fraction [EF] = 76%). In contrast to the class II associations in children, AAH was associated with HLA-DRB1*0405 (RR = 10.4, Pc <.005) but not with HLA-DRB1*1301 or HLA-DRB1*0301. In addition, HLA-DR4 with the class I gene, HLA-A11, appeared synergistic in predisposing AAH patients to develop extra-hepatic autoimmune (AI) manifestations (odds ratio [OR] = 104.9, Pc < 10(-4)). Concomitant differences in autoantibody profiles were also observed in PAH versus AAH: smooth muscle antibodies (SMA) were most prevalent in PAH but antinuclear antibodies were most prevalent in AAH (P =.003). This study therefore reveals that different HLA-DRB1 allotypes confer susceptibility to AH in children and adults and raises the possibility that PAH and AAH may be triggered by different factors.

Short-term cyclosporine induces a remission of autoimmune hepatitis in children.

BACKGROUND/AIMS: The current immunosuppressive treatment of patients with autoimmune hepatitis consists of prednisone and azathioprine. High doses of prednisone used to obtain the remission of the disease are associated with serious adverse effects. To avoid harmful consequences of prednisone therapy, we proposed to treat patients with oral cyclosporine to obtain the remission of the inflammatory process. METHODS: This is a pilot, multinational, multicenter, clinical trial involving children with autoimmune hepatitis. Thirty-two children were recruited, who according to international criteria were considered as having definite autoimmune hepatitis. Cyclosporine alone was administered for 6 months, followed by combined low doses of prednisone and azathioprine for 1 month, after which cyclosporine was discontinued. Biochemical remission of the disease was established by the follow-up of serum transaminase activity levels. Growth parameters and adverse effects of the treatment were recorded. RESULTS: Two patients were withdrawn from the study: one for non-compliance and the other for liver failure which did not improve with cyclosporine. Of the 30 remaining patients, 25 normalized alanine aminotransferase activity levels by 6 months and all the patients by 1 year of treatment. Z-scores for height showed a trend towards improvement during treatment. Adverse effects of cyclosporine were mild and disappeared during weaning off the medication. CONCLUSIONS: Cyclosporine induced the biochemical remission of the hepatic inflammatory/necrotic process in children with autoimmune hepatitis, with few and well-tolerated adverse effects.