title: Specificity of a Polyclonal Fecal Elastase ELISA for CELA3.
abstract: BACKGROUND
  Elastase is a proteolytic pancreatic enzyme that passes through the gastrointestinal tract undergoing only limited degradation. ELISA tests to determine stool elastase concentrations have therefore been developed for the diagnosis of exocrine pancreatic insufficiency. Five different isoforms of pancreatic elastase (CELA1, CELA2A, CELA2B, CELA3A, CELA3B) are encoded in the human genome. We have investigated three different polyclonal antisera that are used in a commercial fecal elastase ELISA to determine their specificity for different pancreatic elastase isoforms.
  
  
  METHODS
  Different polyclonal rabbit antisera against human elastase peptides (BIOSERV Diagnostics GmbH, Germany) were tested by Western blot analysis of human pancreatic juice, in HEK-293 cells expressing Elastase constructs, and in the protein content of porcine pancreatin, used for treatment of exocrine pancreatic insufficiency.
  
  
  RESULTS
  In human pancreatic juice the polyclonal antisera detected proteins at the corresponding size of human pancreatic elastase isoforms (~29kDa). Transiently expressed GFP fusion protein of elastase isoform CELA3A (CELA3A-GFP), but not CELA2A (CELA2A-GFP) could be precipitated from HEK-293 cell lysates with the elastase antisera. We detected no cross-reactivity with elastases in the porcine pancreatic extracts (pancreatin) used for enzyme replacement therapy.
  
  
  CONCLUSIONS
  The polyclonal antisera used in a commercial fecal elastase ELISA are specific for the human pancreatic elastase isoform CELA3 and do not cross-react with elastase contained in pig pancreatin. While pancreatic elastase 1 (CELA1) is not expressed in the adult human pancreas, possible differences between the other isoforms regarding their cellular expression, pathophysiological role and relevance in exocrine pancreatic insufficiency deserve further investigation.
authors.affiliation: University Medicine Greifswald, Department of Medicine A, Ferdinand Sauerbruch-Str., D-17475 Greifswald, Germany.
authors.forename: Frank Ulrich
authors.identifier: http://orcid.org/0000-0003-3369-6369
authors.initials: FU
authors.lastname: Weiss
authors.affiliation: University Medicine Greifswald, Department of Medicine A, Ferdinand Sauerbruch-Str., D-17475 Greifswald, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Budde
authors.affiliation: University Medicine Greifswald, Department of Medicine A, Ferdinand Sauerbruch-Str., D-17475 Greifswald, Germany.
authors.forename: Markus M
authors.initials: MM
authors.lastname: Lerch
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D000918:Antibody Specificity / Q000276:immunology; D003429:Cross Reactions / Q000276:immunology; D056947:Enzyme Replacement Therapy; D004797:Enzyme-Linked Immunosorbent Assay; D010188:Exocrine Pancreatic Insufficiency / Q000175:diagnosis / Q000201:enzymology / Q000628:therapy; D005243:Feces / Q000201:enzymology*; D006801:Humans; D010179:Pancreas / Q000201:enzymology / Q000378:metabolism; D010196:Pancreatic Elastase / Q000276:immunology / Q000378:metabolism*; D020033:Protein Isoforms; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
chemical_list: D000906:Antibodies; D020033:Protein Isoforms; C000617121:CELA3A protein, human; D010196:Pancreatic Elastase