Identification of the platelet glycoprotein IIb/IIIa complex as a target antigen in primary biliary cirrhosis-associated autoimmune thrombocytopenia. Evidence that platelet-reactive autoantibodies can also bind to the mitochondrial antigen M2.
A 67-year-old woman with a 4-year history of primary biliary cirrhosis (PBC) unexpectedly developed autoimmune thrombocytopenia. The platelet-bound IgG antibody was eluted from the patient's platelets to determine the platelet target antigen. The autoantibodies were found to precipitate the platelet glycoprotein complex IIb/IIIa of autologous and allogeneic platelets. A further precipitate of 70 kDa was detectable under reducing conditions. In addition, platelet-reactive antibodies bound to the 70 kDa mitochondrial antigen M2. No cross-absorption studies were performed to confirm that a single antibody reacted with both antigens. Computer analysis of published peptide sequences of the mitochondrial protein and the platelet GPIIb/IIIa complex showed partial amino acid sequence homology suggesting the possibility of a common antibody binding site. These findings suggest a relationship between the development of autoimmune thrombocytopenia in PBC and the underlying liver disease.
Panzer
S
S
First Internal Medical Clinic, University of Vienna, Austria.
Penner
E
E
Nelson
P J
PJ
Prochazka
E
E
Benda
H
H
Saurugger
P N
PN
D000368:Aged; D000595:Amino Acid Sequence; D001323:Autoantibodies / Q000097:blood; D001324:Autoantigens / Q000097:blood; D001327:Autoimmune Diseases / Q000209:etiology / Q000276:immunology*; D001792:Blood Platelets / Q000276:immunology; D051047:Dihydrolipoyllysine-Residue Acetyltransferase; D005260:Female; D006801:Humans; D007074:Immunoglobulin G; D008105:Liver Cirrhosis, Biliary / Q000150:complications / Q000276:immunology*; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D010980:Platelet Membrane Glycoproteins / Q000276:immunology*; D013921:Thrombocytopenia / Q000209:etiology / Q000276:immunology*
D001323:Autoantibodies; D001324:Autoantigens; D007074:Immunoglobulin G; D024101:Mitochondrial Proteins; D010980:Platelet Membrane Glycoproteins; C052359:DLAT protein, human; D051047:Dihydrolipoyllysine-Residue Acetyltransferase