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Opsonic function and concentration of human serum ficolin/P35
S Taira1, N Kodama, M Matsushita
1Department of Neurosurgery, Fukushima Medical University School of Medicine, Fukushima city, Japan.
Fukushima Journal of Medical Science
|July 12, 2001
Summary
Ficolin/P35 acts as an opsonin, enhancing the immune response against pathogens with N-acetylglucosamine (GlcNAc). This collagenous lectin plays a role in innate immunity by facilitating pathogen clearance.
Area of Science:
- Immunology
- Biochemistry
Background:
- Collectins are C-type lectins involved in pathogen recognition and opsonization.
- Ficolin/P35, a human serum lectin, possesses collagenous and fibrinogen-like domains and binds N-acetylglucosamine (GlcNAc).
Purpose of the Study:
- To investigate the opsonic activity of ficolin/P35 against pathogens.
- To determine the role of ficolin/P35 in innate immunity.
- To establish a method for quantifying human serum ficolin/P35 levels.
Main Methods:
- Binding assays using Salmonella typhimurium strains with varying surface GlcNAc expression.
- Phagocytosis assays with monocytes and polymorphonuclear leukocytes.
- Development of a monoclonal antibody-based ELISA for ficolin/P35 quantification.
Main Results:
- Ficolin/P35 bound to Salmonella typhimurium TV119 (Ra chemotype) with exposed GlcNAc but not to strain LT2 (smooth type) with masked GlcNAc.
- Ficolin/P35 enhanced the uptake of TV119 by immune cells, demonstrating opsonic activity.
- The mean serum concentration of ficolin/P35 in 130 normal individuals was 13.7 microg/ml.
Conclusions:
- Ficolin/P35 functions as an opsonin, contributing to innate immunity against specific pathogens expressing GlcNAc.
- Ficolin/P35's opsonic activity is dependent on the accessibility of surface GlcNAc.
- A reliable ELISA method was established for measuring ficolin/P35 serum concentrations.