Primary biliary cirrhosis (PBC): characterization of a monoclonal antibody (PBC-MoAb) having specificity identical with disease-associated autoantibodies.
We have raised a monoclonal antibody (PBC-MoAb) directed against mitochondria which resembles patent anti-mitochondrial autoantibodies (AMA) (M2 type) in several respects. The reaction pattern of PBC-MoAb was characterized by western blot experiments, immunoaffinity purification and enzyme inhibition studies. PBC-MoAb reacts specifically with an epitope on the E2 subunit of pyruvate dehydrogenase (dihydrolipoamide acyltransferase) which is essential for enzymatic activity. This was shown as follows: (1) PBC-MoAb, like PBC-AMA, completely inhibited PDH enzyme activity and reacted weakly with OGDH; (2) PBC-MoAb bound strongly to the E2 subunit in western blots, with weaker binding to a doublet of about 56 kDa; and (3) in immunosorbent experiments, PBC-MoAb absorbed most (greater than 95%) of the AMA reactive material found in solubilized mitochondria. The present data together with earlier findings that the majority of PBC patient autoantibodies bind to epitopes defined by the PBC-MoAb, makes this antibody a valuable tool for characterizing the major PBC-associated epitope on PDH-E2 and localizing this epitope in liver tissue.
Björkland
A
A
Department of Biochemsitry and Immunology, Kabi AB, Stockholm, Sweden.
Mendel-Hartvig
I
I
Nelson
B D
BD
Tötterman
T H
TH
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology*; D001666:Binding Sites, Antibody / Q000276:immunology; D002417:Cattle; D003429:Cross Reactions; D000939:Epitopes / Q000276:immunology; D007655:Ketoglutarate Dehydrogenase Complex / Q000037:antagonists & inhibitors; D008105:Liver Cirrhosis, Biliary / Q000276:immunology*; D008929:Mitochondria, Heart / Q000276:immunology; D011768:Pyruvate Dehydrogenase Complex / Q000037:antagonists & inhibitors
D000911:Antibodies, Monoclonal; D001323:Autoantibodies; D000939:Epitopes; D011768:Pyruvate Dehydrogenase Complex; D007655:Ketoglutarate Dehydrogenase Complex