Lack of informative HLA restriction fragment length polymorphisms in autoimmune chronic active hepatitis

[Autoimmune hepatitis and hepatitis C]

From autoimmune hepatitis (AIH) classification which recognizes three types of AIH, we discuss the main relations between hepatitis C virus (HCV) infection and AIH. Type I AIH is associated with antinuclear and antismooth muscle antibodies, and with other autoimmune diseases. There is no relation between type I AIH and HCV. Type I anti-liver kidney microsome and anti-liver cytosol I antibodies represent the hallmark of type II AIH. Among type II AIH, two subgroups emerged: type IIa AIH (10-40%) are true AIH (sensitive to steroids but worsens with interferon alpha), whereas type IIb AIH (60-90%) appear as a particular form of HCV hepatitis. Type IIb AIH have a moderate activity, a low titer of autoantibodies, anti-GOR antibodies but never anti-liver cytosol I, no sensitivity to steroids but are sensitive to interferon alpha. The hallmark of type III AIH are anti-cytosol antibodies, but these AIH have the same characteristics as type I AIH. The classification between true AIH (I, IIa, III) or "pseudo-AIH" due to HCV infection has major therapeutic implications. Steroids or immunosuppressive treatments are effective in type I, IIa and III AIH but have no efficacy in type IIb AIH. Alpha interferon has an efficacy in type IIb AIH, but it has no efficacy and may even worsen hepatitis in type I, IIa and III AIH.

HLA class II molecules and autoimmune hepatitis susceptibility in Japanese patients

To investigate the association between autoimmune hepatitis and HLA alleles in Japanese patients, serological typing and class II genotyping were performed using the polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) method. Serological typing showed that HLA-B54, -DR4, -DR53, and -DQ4 were significantly more frequent in patients with autoimmune hepatitis than in controls. HLA-DR4 was most frequently associated with autoimmune hepatitis (88.7%). In PCR-RFLP typing, the frequency of DRB1*0405 was significantly higher in autoimmune hepatitis than in controls. However, there was no significant difference in the frequency of Dw between the patients and the controls who were DR4-positive. The significant increase observed in DQA1*0301 and DQB1*0401 was explained by a linkage disequilibrium with DR4. Six DR4-negative patients had DR2, but there was no significant difference in the frequency of the DR2-associated Dw-alleles compared with the DR2-positive controls. No DPB1 allele was significantly associated with autoimmune hepatitis. These findings suggest that the basic amino acid at position 13, which is present only on the DR2 and DR4 B1 molecules (Arg on DR2 and His on DR4), contributes to the susceptibility to autoimmune hepatitis among the Japanese.

Association of autoimmune hepatitis with HLA-Bw54 and DR4 in Japanese patients

Human leukocyte antigen-D region-related alleles (human leukocyte antigen DR and DQ) and human leukocyte antigen class I alleles were typed serologically in 31 Japanese patients with autoimmune hepatitis. These patients had increased serum levels of AST and IgG, high titers of autoantibodies, no history of blood transfusion and were negative for HBsAg and antibodies to HBc. Three hundred eighty-six healthy subjects and 30 patients with cryptogenic chronic hepatitis served as control groups. The frequency of DR4 was significantly higher in autoimmune hepatitis patients (90.3%) than in healthy subjects (38.6%) and in cryptogenic chronic hepatitis patients (30%). The frequency of Bw54 was significantly higher in autoimmune hepatitis patients (45.2%) than in healthy subjects (10.9%). The risk to DR4-positive subjects for autoimmune hepatitis was 14.8 relative to healthy subjects. Two of 31 patients (6.5%) with autoimmune hepatitis were positive for antibody to hepatitis C virus; both clearly satisfied criteria for autoimmune hepatitis and both had Bw54 and DR4. This study revealed a highly significant association of autoimmune hepatitis with human leukocyte antigen Bw54 and DR4 in Japanese patients. Among the DR4-positive patients with autoimmune hepatitis, no significant differences were seen between those positive or negative for Bw54 with regard to clinical or laboratory data, relapse of disease or efficacy of prednisolone. Thus human leukocyte antigen class II alleles contribute to susceptibility and resistance to autoimmune hepatitis in Japanese patients, with distinct racial differences from those in white patients.