Axelgaard, Esben7; Jensen, Lisbeth7; Dyrlund, Thomas Franck8; Nielsen, Hans J6; Enghild, Jan J8; Thiel, Steffen7; Jensenius, Jens C7
1 Department of Molecular Biology and Genetics - Protein science, Department of Molecular Biology and Genetics, Science and Technology, Aarhus University2 Department of Biomedicine, Health, Aarhus University3 Department of Biomedicine - Forskning og uddannelse, Øst, Department of Biomedicine, Health, Aarhus University4 Interdisciplinary Nanoscience Center - INANO-MBG, Gustav Wied 10, Interdisciplinary Nanoscience Center, Science and Technology, Aarhus University5 Department of Bioscience - Arctic Research Centre, Wilhelm Meyers Allé, Department of Bioscience, Science and Technology, Aarhus University6 Studies Guidance, Faculty of Science, Aarhus University, Aarhus University7 Department of Biomedicine - Forskning og uddannelse, Øst, Department of Biomedicine, Health, Aarhus University8 Department of Molecular Biology and Genetics - Protein science, Department of Molecular Biology and Genetics, Science and Technology, Aarhus University
Collectins are pattern recognition molecules of the innate immune system showing binding to carbohydrate structures on microorganisms in a calcium-dependent manner. Recently, three novel collectins, collectin liver 1 (CL-L1), collectin kidney 1 (CL-K1 and CL-11), and collectin placenta 1 (CL-P1), were discovered. The roles of these three collectins remain largely unknown. Here, we present a time-resolved immunofluorometric assay for quantification of CL-L1. The concentration of CL-L1 in donor plasma (n = 210) was distributed log-normally with a median value of 3.0 μg/ml (range 1.5-5.5 μg/ml). We observed on average 30% higher concentrations of CL-L1 in plasma as compared with serum. Size analysis by gel-permeation chromatography showed CL-L1 in serum to elute as large 700-800-kDa complexes and smaller 200-300-kDa complexes. CL-L1 showed specific binding to mannose-TSK beads in a Ca(2+)-dependent manner. This binding could be inhibited by mannose and glucose, but not galactose, indicating that CL-L1 binds via its carbohydrate-recognition domain and has ligand specificity similar to that of mannan-binding lectin. Western blot analysis of CL-L1 showed the presence of several oligomeric forms in serum. Ontogeny studies showed CL-L1 to be present at birth at near adult levels. CL-L1 levels exhibit low variation in healthy adults over a 1-year period. During acute-phase responses, the CL-L1 levels display only minor variations. In serum, CL-L1 was found in complexes with mannan-binding lectin-associated serine proteases, suggesting a role in the lectin pathway of complement activation. The presented data establish a basis for future studies on the biological role of CL-L1.
Journal of Biological Chemistry, 2013, Vol 288, Issue 32, p. 23407-23420