title: Ficolin-2 reveals different analytical and biological properties dependent on different sample handling procedures.
abstract: Ficolin-2 (L-ficolin) is a germ line encoded pattern recognition molecule circulating in the blood, and functions as a recognition molecule in the lectin complement pathway. However, consistent and reliable measurements of Ficolin-2 concentration and activity have been difficult to achieve. After recurrent observations of deviations in Ficolin-2 properties between different blood sample procedures, we decided to investigate this closer. Blood samples from ten healthy donors were collected in various serum and plasma tubes and Ficolin-2 properties were evaluated by different ELISA setups. We found that serum prepared from tubes containing the clot activator silica used as a standard technique in many routine laboratories held a significantly lower concentration of Ficolin-2 as compared to the other sample types. Furthermore, Ficolin-2 binding and complement activation potential in this type of serum was impaired when using an acetylated compound as matrix. On the other hand, Ficolin-2 in serum made without clot activator and in plasma irrespective of additive used, had the same concentration and was capable of initiating the lectin pathway measured as C4 and C3 deposition on the ligand. No Ficolin-2 mediated formation of the terminal complement complex was observed under the applied assay conditions. In conclusion, our results show that Ficolin-2 is a promiscuous molecule and that care should be taken during sampling, handling and matrix chosen for measurement of Ficolin-2 levels and activity.
authors.affiliation: Laboratory of Molecular Medicine, Department of Clinical Immunology, Rigshospitalet, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Estrid
authors.initials: E
authors.lastname: Hein
authors.forename: Jakob T
authors.initials: JT
authors.lastname: Bay
authors.forename: Lea
authors.initials: L
authors.lastname: Munthe-Fog
authors.forename: Peter
authors.initials: P
authors.lastname: Garred
mesh_terms: D001774:Blood Chemical Analysis / Q000295:instrumentation / Q000379:methods*; D001800:Blood Specimen Collection / Q000295:instrumentation / Q000379:methods*; D003176:Complement C3 / Q000378:metabolism; D003181:Complement C4 / Q000378:metabolism; D037582:Complement Pathway, Mannose-Binding Lectin; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D037102:Lectins / Q000097:blood* / Q000737:chemistry / Q000378:metabolism; D008024:Ligands; D015203:Reproducibility of Results; D044967:Serum / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry; D000097604:Ficolins
chemical_list: D003176:Complement C3; D003181:Complement C4; D037102:Lectins; D008024:Ligands; D012822:Silicon Dioxide; D000097604:Ficolins
keywords: Blood sampling; ELISA; Ficolin-2; Ficolin-3 complement; L-ficolin; Lectin pathway; Ligand specificity; MASP; MBL; MBL/ficolin/collectin associated serine protease; Plasma; SPS; Sampling; Serum; Silica; TCC; acBSA; acetylated bovine serum albumin; enzyme linked immunosorbent assay; mannose-binding lectin; sodium polyanethole sulfonate; terminal complement complex