title: A soluble form of the macrophage-related mannose receptor (MR/CD206) is present in human serum and elevated in critical illness.
abstract: BACKGROUND
  This study tests the hypothesis that the mannose receptor (MR/CD206), which is expressed primarily by macrophages and dendritic cells, can be found in a soluble form (sMR, sMR) in human serum. Furthermore, we wished to establish and validate an enzyme-linked immunosorbent assay (ELISA) for sMR and to perform initial studies exploring the potential of sMR as a biomarker.
  
  
  METHODS
  Western blotting identified a single band of approximately 170 kDa in human serum, and MALDI MS/MS of the purified protein confirmed it to be sMR. An ELISA was established and validated with a measurement range of 1-256 µg/L.
  
  
  RESULTS
  The 95% reference interval was 0.10-0.43 mg/L based on measurements of serum samples from healthy individuals (n=217). Samples from hospitalised patients (n=219) revealed that more than 50% of patients had concentrations above 0.43 mg/L. Very high concentrations (up to 6.2 mg/L) were observed in critically ill patients with sepsis and/or severe liver disease.
  
  
  CONCLUSIONS
  This study documents, for the first time, the presence of sMR in human serum and describes an optimised ELISA suitable for quantitative measurements. Levels of sMR are strongly elevated in several disease states, including sepsis and liver disease, and the protein therefore shows promise as a new biomarker.
authors.forename: Sidsel
authors.initials: S
authors.lastname: Rødgaard-Hansen
authors.forename: Aisha
authors.initials: A
authors.lastname: Rafique
authors.forename: Peter A
authors.initials: PA
authors.lastname: Christensen
authors.forename: Maciej B
authors.initials: MB
authors.lastname: Maniecki
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Sandahl
authors.forename: Ebba
authors.initials: E
authors.lastname: Nexø
authors.forename: Holger Jon
authors.initials: HJ
authors.lastname: Møller
mesh_terms: D015415:Biomarkers / Q000097:blood / Q000737:chemistry; D016638:Critical Illness; D004797:Enzyme-Linked Immunosorbent Assay; D006760:Hospitalization; D006801:Humans; D037181:Lectins, C-Type / Q000097:blood* / Q000737:chemistry*; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins / Q000097:blood* / Q000737:chemistry*; D008875:Middle Aged; D011956:Receptors, Cell Surface / Q000097:blood* / Q000737:chemistry*; D012016:Reference Values; D015203:Reproducibility of Results; D012995:Solubility
chemical_list: D015415:Biomarkers; D037181:Lectins, C-Type; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D011956:Receptors, Cell Surface