PBC 95K, a 95‐kilodalton nuclear autoantigen in primary biliary cirrhosis

Abstract

We have identified a novel antinuclear antibody (ANA) in the sera of patients with primary biliary cirrhosis (PBC). Sera from 22 of 50 PBC patients stained the nuclei of HEp-2 cells in a pattern of 5-20 discrete dots, on indirect immunofluorescence. Typically, the titers were higher than 1:1,280. This staining pattern was seen in only 4 of 1,240 ANA-positive samples from patients with other connective tissue diseases, and in none of the ANA-positive sera from 49 patients with other liver diseases. Sera which stained the nuclear dots bound a 95-kd polypeptide in immunoblots of HeLa nuclei and in immunoprecipitates of 35S-methioninelabeled HeLa extracts. Affinity-purified antibodies from the 95-kd protein reproduced the nuclear dot immunofluorescence staining pattern, demonstrating that this polypeptide is located in the nuclear dots. ANA of this type, therefore, occur in 44% of patients with PBC, and they appear to be specific for PBC. These antibodies bind a 95-kd protein that is discrete and is scattered throughout the nucleus. Primary biliary cirrhosis (PBC) is an autoimmune disease that primarily affects the liver, resulting in cholestasis, progressive hepatic fibrosis, and cirrhosis (1). Antiinitochondrial antibodies are a characteristic feature of PBC, occurring in more than 95% of patients (2). Although 9 different antimitochondrial antibody specificities have been identified, the most common and most specific for PBC is the anti-M2 antibody (3). The M2 antigen is composed of 4 polypeptides of the inner mitochondria1 membrane that have molecular weights of approximately 74 kd, 52 kd, 45 kd, and 39 kd (4). More recently, the M2 antigen has been shown to consist of 4 metabolic ent.ymes: pyruvate dehydrogenase, branched chain 2-oxo-acid dehydrogenase, oxo-glutarate dehydrogenase, and protein X (4). These proteins are found widely in nature. Using sera from patients with PBC as probes, the proteins have been found in all eukaryotic cells examined to date, including yeasts (5,6).In contrast, antinuclear antibodies (ANA) in patients with PBC have been less well-characterized. We have recently identified an autoantibody specificity in sera from patients with PBC that stains the nucleus in a pattern of 5-20 discrete dots, by indirect immunofluorescence. The antigenic target of these antibodies is a nuclear protein of 95 kd, which we have called PBC 95K. PATIENTS AND METHODSSera. Serum samples from 50 patients with biopsyproven primary biliary cirrhosis were screened by indirect immunofluorescence on HEp-2 cells. The diagnosis of PBC was made based on the usual clinical. biochemical, and serologic abnormalities and characteristic histopathologic

Primary Biliary Cirrhosis (PBC), PBC Autoantibodies, and Hepatic Parameter Abnormalities in a Large Population of Systemic Sclerosis Patients

“…Previous studies indicated a higher frequency of other autoimmune diseases in patients with AMA-negative PBC in comparison to AMA-positive PBC cases7,18. Eighteen percent to 44% of patients with PBC have autoantibodies against sp10019,20, a nuclear protein identified as a “multiple nuclear dots” pattern when examined by indirect immunofluorescence (IIF) microscopy. According to published reports, these antibodies are highly specific for PBC and have been detected in very few subjects without the disease19–22.…”

“…Eighteen percent to 44% of patients with PBC have autoantibodies against sp10019,20, a nuclear protein identified as a “multiple nuclear dots” pattern when examined by indirect immunofluorescence (IIF) microscopy. According to published reports, these antibodies are highly specific for PBC and have been detected in very few subjects without the disease19–22. In addition, gp210 autoantibodies, which are directed against a component of the nuclear pore complex, have been reported to have a sensitivity of 9.4% to 29% and a specificity of more than 99% for PBC23–25.…”

Identification and Characterization of a Leukocyte-specific Component of the Nuclear Body

“…Approximately 40% of patients with PBC have antibodies directed against this structure (4,5). Serum from patients with PBC was used to identify and characterize a 100-kDa component of the NB which was designated Sp100 (Speckled, 100-kDa) (6).…”

An ELISA-based high throughput protein truncation test for inherited breast cancer

“…One hundred human genomic clinical DNA samples isolated from blood and previously characterized by the conventional gel-based PTT (method as described in [19]) were used for HTS-PTT. The genomic DNA was extracted from peripheral blood leukocytes by means of the Gentra Puregene Blood Kit (Gentra Systems, Minneapolis, MN, USA).…”