PRECIPITATING ANTIBODIES TO MITOCHONDRIAL ANTIGENS IN PATIENTS WITH PRIMARY BILIARY-CIRRHOSIS

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  • 1 January 1980
    • journal article
    • research article
    • Vol. 39  (3) , 599-606
Abstract
Sera of patients with primary biliary cirrhosis (PBC) were examined for the presence of precipitating antibodies to sonicated rat liver mitochondrial (M) fraction. Three distinct precipitating systems observed in double immunodiffusion were identified and called M-A, M-B and M-C. Unsonicated mitochondria did not form precipitin lines. Precipitating system M-A was found in 19 of 20 (95%) sera from PBC. The mitochondrial antigen of M-A system had the unusual property of being resistant to enzymatic digestion with DNase, ribonuclease (RNase) and trypsin under standard conditions. The titers of antibody to M-A antigen correlated (P < 0.05) with titers of mitochondrial immunofluorescence staining on unfixed mouse kidney sections. Precipitating systems M-B and M-C were present in 7 of 20 (35%) and 5 of 20 (25%) patients, respectively. The M-B antigen was sensitive to deoxyribonuclease and trypsin but resistant to ribonuclease, indicating that it could be DNA-protein complex. The M-C antigen was destroyed by trypsin suggesting its protein character, but it was difficult to determine if nucleic acids might also be associated with antigenicity. The antibodies to mitochondrial antigens were not present in normals (15 healthy adults), systemic lupus erythematosus (40 patients), rheumatoid arthritis (15 patients) and chronic liver diseases (15 patients). The antibodies did not show identity with antibodies to ribosomal ribonucleoprotein and other known nuclear antigens previously reported. The data confirm previous reports concerning the heterogeneity of mitochondrial antibodies present in sera of patients with PBC. The antibody to M-A antigen appeared to be a diagnostically useful immunological marker since it was present in the majority of patients with PBC.