Autoimmune pancreatitis (AIP) is a rare form of chronic pancreatitis, clinically mimicking pancreatic cancer. In 2009, a serological diagnostic test detecting antibodies against plasminogen-binding protein (PBP) ofHelicobacter pyloriwas reported with outstanding test performances (NEJM 361:135). We aimed to validate these findings.
Between March 2007 and May 2011, sera were collected from consecutive patients presenting with type 1 AIP, pancreatic ductal adenocarcinoma (PDAC), chronic pancreatitis (CP), primary sclerosing cholangitis (PSC), and healthy controls (HC) with or without antibodies againstH. pylori. Serum antibody binding to synthetic PBP peptide was quantified by enzyme-linked immunosorbent assay (ELISA), using standard curves of custom-made PBP rabbit polyclonal antibodies. A synthetic Flag peptide (DYKDDDK), to which no antibodies are found in human serum, was included as negative control.
High sensitivity of PBP peptide recognition was demonstrated by selective binding of PBP peptide over Flag peptide by PBP-immunized rabbit serum. Competition assays with PBP peptide validated the selectivity for antibodies recognizing this antigen. A total of 114 patients were subsequently tested: 34 AIP, 29 PDAC, 17 CP, 16 PSC, and 18 HCs (9 positive and 9 negative forH. pylori). No significant differences in detection of antibodies against the PBP peptide were found between different the patient groups and healthy controls.
Using a sensitive and selective ELISA-based assay, we did not find increased serum antibodies against PBP peptide in AIP patients. PBP serum antibodies are therefore not a useful diagnostic tool to diagnose AIP.
1Department of Gastroenterology and Hepatology, Erasmus University Medical Center, Rotterdam, The Netherlands
2Department of Public Health, Erasmus University Medical Center, Rotterdam, The Netherlands
Correspondence: Jorie Buijs, MD, PhD, Department of Gastroenterology and Hepatology, Erasmus University Medical Center, Room HS 322K, PO Box 2040, Rotterdam 3000 CA, The Netherlands. E-mail: email@example.com
SUPPLEMENTARY MATERIAL accompanies this paper at http://links.lww.com/AJG/A874, http://links.lww.com/AJG/A876, http://links.lww.com/AJG/A878, http://links.lww.com/AJG/A879
Received 24 February 2016; accepted 11 May 2016
Guarantor of the article: Marco J. Bruno, MD, PhD.
Specific author contributions: Study concept and design, data acquisition, data analysis and interpretation, drafting of the manuscript, critical revision of the manuscript for important intellectual content, statistical analysis, and study supervision: J.B., G.M.F., M.P.P., M.J.B., and H.R.B. Statistical analysis and drafting of the manuscript: B.E.H. Patient enrollment, data acquisition, and critical revision of the manuscript for important intellectual content: D.L.C., M.J.H., B.E.H., and H.R.B.
Financial support: None.
Potential competing interests: None.