[Serum autoantibodies of patients with chronic hepatitis C and the significance thereof in infection of hepatitis C virus].

OBJECTIVE: To investigate the serum autoantibodies in patients with chronic hepatitis C and to investigate the significance of autoimmune reaction in hepatitis C virus (HCV) infected patients.

METHODS: Peripheral blood samples were collected from 69 patients with chronic hepatitis C, 69 patients with chronic hepatitis B (HB), and 69 patients with autoimmune hepatitis (AIH). Indirect immunofluorescence technique was used to detect the serum anti nuclear antibody (ANA), anti-mitochondrial antibody (AMA), anti-smooth muscle antibody (anti-SMA), and anti-liver-kidney antibody (anti-LKM). HCV RNA was detected by PCR. The biochemical indices: alanine transaminase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL), and gamma-globulin were detected. The relations of autoantibodies to virus load, HCV genotype, cirrhosis, age, sex, and liver function were analyzed.

RESULTS: (1) Twenty of the HCV patients were positive in autoantibodies, most being at a low titer, 11 of them being positive in ANA, 7 in anti-SMA, 1 in anti-AMA, and 1 in anti-LKM, with a positive rate of 28.9%, significantly higher than that of the HB patients (4.3%, P < 0.05), and significantly lower than that of the AIH patients (100%, P < 0.05). (2) There were no significant differences between the autoantibody positive group and autoantibody negative group in virus load and HCV genotype. (3) Fourteen of the 18 patients positive in autoantibodies responded to the anti-virus treatment with alpha-interferon with a response rate of 77.8%, significantly higher than that of the autoantibody negative group (53%, P < 0.05). (4) The average age of the autoantibody positive group was 47 +/- 18 years, significantly higher than that of the autoantibody negative group (39 +/- 12 years, P < 0.05). The positive autoantibody rate of the patients aged >or= 40 was 23.1%, significantly higher than that of the patients aged < 40 (5.8%, P < 0.05). There was no significant difference in the autoantibody rate between males and females. (5) The cirrhosis prevalence rate of the autoantibody positive group was 80%, significantly higher than that of the autoantibody negative group (46.9%, P < 0.05). (6) The serum ALT, AST, TBIL and gamma-globulin of the autoantibody positive group were 191 U/L +/- 89 U/L, 169 U/L +/- 80 U/L, 78 micromol/L +/- 50 micromol/L, and 200 g/L +/- 80 g/L respectively, all significantly higher than those of the autoantibody negative group (113 U/L +/- 69 U/L, 98 U/L +/- 62 U/L, 51 micromol/L +/- 30 micromol/L, and 160 g/L +/- 70 g/L respectively, all P < 0.05). (7) There were no significant differences in HCV RNA load and HCV genotype between the autoantibody positive group and the autoantibody negative group (both P > 0.05).

CONCLUSION: HCV infection induces the autoimmune reaction resulting in production of autoantibodies. Positive autoantibody rate is related with cirrhosis and age. Titer and type of autoantibody serve as important indices in the diagnosis and treatment of HCV.