FREQUENCY AND SIGNIFICANCE OF ANTIBODIES TO ACTIN IN TYPE-1 AUTOIMMUNE HEPATITIS

Antibodies to actin have been proposed as diagnostic markers for type 1 autoimmune hepatitis, Our aims were to determine 1) if testing for a ntibodies to actin is superior to testing for smooth muscle antibodies (SMA); 2) if these antibodies identify patients with distinctive clin ical features; and 3) if the production of antibodies to actin is asso ciated with genetic risk factors for autoimmune hepatitis, Sera from 9 9 patients with type 1 autoimmune hepatitis were tested, The frequenci es of HLA B8, DR3, DR4, and A1-B8-DR3 in patient subsets were compared with those in 80 normal subjects, Seventy-three patients (74%) had an tibodies to actin, Antibodies to actin were found more commonly in pat ients with SMA than in patients without them (86% vs, 7%, P < .0001), Screening only for antibodies to actin and antinuclear antibodies (ANA ) failed to establish the diagnosis of autoimmune hepatitis in 5 patie nts, Patients with antibodies to actin were younger than seronegative patients, They were also more commonly DR3-positive than normal subjec ts and more frequently B8-positive than patients with non-actin-associ ated SMA (49% vs, 0%, P =.004), Only patients with antibodies to actin died of liver failure (6% vs, 0%), and 10 of 11 patients requiring li ver transplantation were seropositive for these antibodies, Indeed, de ath and liver transplantation occurred more frequently in these patien ts than in actin-negative patients with ANA (19% vs, 0%, P =.03), We c onclude that routine screening for antibodies to actin may miss patien ts with type 1 autoimmune hepatitis, Antibodies to actin are associate d with HLA B8 and DR3, and they identify patients with a poor prognosi s.