DETECTION OF ANTI-LIVER CYTOSOL ANTIBODY TYPE-1 (ANTI-LC1) BY IMMUNODIFFUSION, COUNTERIMMUNOELECTROPHORESIS AND IMMUNOBLOTTING - COMPARISONOF DIFFERENT TECHNIQUES

Liver cytosol specific antibody type 1 (anti-LC1) was first described in a proportion of patients with liver/kidney microsomal antibody type 1 (anti-LKM1)-positive autoimmune hepatitis (AIH) and is routinely ev aluated by immunodiffusion (ID). Using human liver cytosol as the sour ce of antigen, we have used ID, counterimmunoelectrophoresis (CIE) and immunoblotting (IB), to test sera from 167 patients with documented c hronic liver diseases of different etiology, 15 patients had antinucle ar antibody (ANA) and/or smooth muscle antibody (SMA)-positive AIH, 13 had anti-LKM1-positive AIH, four had ANA/SMA/anti-LKM1-negative AIH, 76 had anti-LKM1-positive hepatitis C (recently renamed unclassified c hronic hepatitis-UGH), 40 had chronic hepatitis C, 15 had chronic hepa titis B, and 4 had chronic hepatitis D. A precipitin line of identity with an anti-LC1 reference serum was detected both by ID and CIE in 16 patients: six with anti-LKM1-positive 'definite' AIH, four with ANA/S MA/anti-LKM1-negative 'definite' AIH, and six with anti-LKM1-positive UGH. By IB, 14 out of the 16 anti-LC1-positive sera (87.5%) reacted wi th a 58 kDa human liver cytosolic polypeptide, whereas three out of 16 (19%) recognised an additional 60 kDa band. Compared to ID, CIE is mo re economical in terms of both time and reagents and provides more cle ar-cut results. The 58 kDa reactivity by IB was detectable in nearly a ll CIE/ID anti-LC1-positive patients, was not found among CIE/ID anti- LC1-negative patients. In conclusion, CIE is the ideal screening test for the detection of anti-LC1, an autoantibody that can be regarded as an additional serological marker of AIH and is especially useful in A NA/SMA/anti-LKM1 negative cases.