CHRONIC HEPATITIS-C ASSOCIATED WITH ANTI-LIVER KIDNEY MICROSOME-1 ANTIBODY IS NOT A SUBGROUP OF AUTOIMMUNE HEPATITIS/

To determine whether ''autoimmune hepatitis type IIb'' should be categ orized as a subgroup of autoimmune hepatitis, we conducted a clinicopa thological study of 25 adult Japanese patients who were positive for a nti-liver/kidney microsome-1 (anti-LKM-1) antibody and infected with t he hepatitis C virus (HCV). Anti-LKM-1 was determined by indirect immu nofluorescence and by the double immunodiffusion assays we have develo ped. Twenty-two patients did not present any unusual symptoms or any a ssociated diseases during the course of their chronic HCV infection, T he spectrum of HCV genotypes of these patients did not significantly d iffer from that of anti-LKM-1-negative Japanese patients with chronic hepatitis C. Histological examination of liver biopsy specimens showed the usual characteristics of chronic hepatitis C and lack of characte ristics of autoimmune hepatitis type I. No disease-specific HLA haplot ypes were noted, and HLA-DR4, which is detectable in 88.7% of Japanese patients with autoimmune hepatitis type I, was detected in only 50.0% of our group, the same rate as the background frequency. Prednisolone was effective in none of the six patients treated, but interferon was effective, in six of ten treated patients (60%). From these results, we conclude that ''autoimmune hepatitis type IIb'' should not be categ orized as autoimmune hepatitis, and that this subgroup is essentially chronic hepatitis C in which an autoantibody has been produced during the course of chronic HCV infection.