Anti-smooth muscle antibodies (ASMAs) and anti-cytoskeleton antibodies (ACTAs) in liver diseases: a comparison of classical indirect immunofluorescence with ELISA.
In the diagnosis of autoimmune hepatitis type I (AIH-I), the routine assay of indirect immunofluorescence (IFL), used for the detection of anti-smooth muscle antibodies (ASMAs), has a low predictive value. On the other hand, the enzyme-linked immunosorbent assay (ELISA), which detects anti-cytoskeleton antibodies (ACTAs), presents contradictory results concerning their specific antigenic target. In this study, we first looked for the immunological properties (isotypes and antigenic targets) of autoantibodies in AIH-I and two other control liver diseases: primary biliary cirrhosis (PBC) and viral hepatitis (VH), using ELISA based on cytoskeleton proteins: F-actin, G-actin, myosin, tropomyosin, troponin, desmin, vimentin, keratin, and an extract of HEp-2 carcinoma cells. We also compared the diagnostic value of IFL and ELISA. In contrast to previous studies, we found that actin was not specific for AIH-I. No autoantigen and no antibody class or subclass discriminated AIH-I from the control diseases. IFL is more suitable for AIH-I diagnosis, as 97% of AIH-I sera but only 22% of PBC sera were ASMA-positive. Additionally, 96% of ASMA-positive, and all ASMA-negative sera from all three liver diseases were ACTA-positive. ASMA were mainly IgG, while >50% of ACTA also contained IgA and IgM. These data suggest that ACTAs recognize additional epitopes as compared to ASMAs, and they frequently occur in all liver diseases.
Zamanou
A
A
Immunology Laboratory, Biochemistry Department, Hellenic Pasteur Institute, Athens, Greece.
Tsirogianni
A
A
Terzoglou
C
C
Balafas
A
A
Economidou
I
I
Lymberi
P
P
D000906:Antibodies / Q000097:blood / Q000302:isolation & purification*; D000941:Antigens / Q000097:blood / Q000302:isolation & purification; D003598:Cytoskeletal Proteins / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D019084:Fluorescent Antibody Technique, Indirect; D006505:Hepatitis / Q000097:blood / Q000276:immunology*; D006801:Humans; D009130:Muscle, Smooth / Q000276:immunology*
D000906:Antibodies; D000941:Antigens; D003598:Cytoskeletal Proteins