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Updated: Jun 14, 2026

Spot Variation Fluorescence Correlation Spectroscopy for Analysis of Molecular Diffusion at the Plasma Membrane of Living Cells
Published on: November 12, 2020
Characteristics and biological variations of M-ficolin, a pattern recognition molecule, in plasma
Thomas Wittenborn1, Steffen Thiel, Lisbeth Jensen
1Department of Medical Microbiology and Immunology, University of Aarhus, Aarhus, Denmark.
Abstract:
The three human ficolins, H-ficolin, L-ficolin and M-ficolin, are pattern recognition molecules of the innate immune system. All three ficolins can activate the lectin pathway of the complement system after binding to pathogens. H- and L-ficolin are serum proteins with an average concentration of 18 and 3 microg/ml, respectively. M-ficolin has been described as a membrane-associated pattern recognition receptor of monocytes, being also present in granulocytes; recently, minuscule amounts of M-ficolin have been found in serum, too. No assay specific for M-ficolin has yet been described and biological variations are unknown. We have raised specific monoclonal anti-human M-ficolin antibodies and have developed a quantitative assay for M-ficolin. M-ficolin elutes as a large, 900-kDa protein upon gel permeation chromatography of serum. Analysis of M-ficolin levels in serum samples of 350 blood donors reveals a mean concentration of 1.07 microg/ml, ranging from 0.28 to 4.05 microg/ml. Analyses of consecutive acute phase serum samples from major surgery patients indicated a complex response. Ontogeny was investigated through cord blood samples from healthy full-term babies, which showed adult levels, with sequential samples showing no increase from birth to 1 year of age. We suggest that M-ficolin should also be considered as a humoral pattern recognition molecule.
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