High sensitivity of a novel ELISA for anti-M2 in primary biliary cirrhosis

H. Miyakawa et al., High sensitivity of a novel ELISA for anti-M2 in primary biliary cirrhosis, J GASTRO, 36(1), 2001, pp. 33-38
Citations number
Categorie Soggetti
Gastroenerology and Hepatology
Journal title
ISSN journal
0944-1174 → ACNP
Year of publication
33 - 38
SICI code
The use of an ELISA for the detection of anti-M2, a specific autoantibody i n primary biliary cirrhosis (PBC), has been common in Japan. However, there are some problems in the sensitivity of this ELISA, especially in PBC pati ents showing antimitochondrial antibody (AMA)-negative sera or low AMA tite rs by immunofluorescence. Recently, a new ELISA for anti-M2 was developed, using porcine heart mitochondrial protein as the antigen. We report here co mparative studies of the new and the former anti-M2 ELISAs. Porcine heart m itochondrial protein was prepared and used as the antigen for the new ELISA for anti-M2. Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS -PAGE) of this protein showed three major M2 antigen proteins. As the secon d antibody, peroxidase-conjugated anti-human mouse monoclonal IgM, in addit ion to monoclonal IgG, was included. The sera of 171 PBC patients were exam ined. As controls, we examined the sera of 167 non-PBC patients and the ser a of 115 normal controls. The cut-off index was set at 10 U/ml, based on th e results for the normal controls. No sera from the non-PBC patients or the normal controls were positive for anti-M2 by either the new or the former ELISA. However, the positivity rate for anti-M2 in PBC patients with the ne w ELISA was 78%; in contrast, that with the former ELISA was only 54%; this difference was significant (P = 0.00001). In particular, in 65 patients sh owing AMA titers of 1:20 or less, the positivity rate with the new ELISA wa s 51%; in contrast, that with the former ELISA was only 17%. As the sensiti vity of the new ELISA is significantly higher than that of the former ELISA , especially for sera from patients showing AMA-negativity or low titers of AMA, the new ELISA is considered to be more effective than the former ELIS A for use in anti-M2 screening assays in patients with PBC.