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Updated: Aug 8, 2026
Murine Model of CD40-activation of B cells
Published on: March 6, 2010
Phenotypic analysis of the murine CD4-related glycoprotein, CD223 (LAG-3)
Creg J Workman1, Dennis S Rice, Kari J Dugger
1Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105-2794, USA.
Insights
Murine CD223 (LAG-3) is expressed in specific brain regions and on certain immune cells. This study characterizes its expression patterns and function, aiding future research.
Area of Science:
- Immunology
- Neuroscience
- Cell Biology
Background:
- CD223 (LAG-3) is a T cell surface molecule structurally similar to CD4.
- Its expression and function in mice are largely uncharacterized.
- CD223 binds to MHC class II molecules.
Purpose of the Study:
- To investigate the expression pattern of murine CD223 (mCD223) in adult and developing brain, as well as in immune cells.
- To characterize the function of mCD223 using a novel monoclonal antibody.
- To identify immune cell populations expressing mCD223.
Main Methods:
- Analysis of mCD223 mRNA expression in various tissues.
- Use of mCD223:Ig and CD4:Ig fusion proteins to identify binding targets.
- Development and application of a new monoclonal antibody against mCD223.
- Flow cytometry to assess mCD223 surface expression on T cells and NK cells.
- BrdU incorporation assay to identify cycling cells.
Main Results:
- mCD223 mRNA is found in the thymic medulla, splenic red pulp, and specific brain regions, including the cerebellum and choroid plexus in postnatal development.
- mCD223:Ig fusion protein binds to MHC class II-expressing cells.
- A novel mAb against mCD223 blocks mCD223 function in vitro but not its binding to MHC class II.
- Naive mice show low mCD223 expression on TCRαβ T cells (<3%), but higher expression on TCRγδ T cells (~18%) and NK cells (~10%).
- Activated T cells upregulate mCD223 expression.
Conclusions:
- Murine CD223 exhibits distinct expression patterns in the brain and immune system.
- The novel anti-mCD223 mAb is a valuable tool for studying CD223 function.
- mCD223 is expressed on specific T cell subsets and NK cells, and its expression is upregulated upon T cell activation.
Abstract:
CD223 (LAG-3) is an activation-induced cell surface molecule, structurally similar to the T cell coreceptor CD4, that binds MHC class II molecules with high affinity. Little is known about the expression and function of murine CD223. Here, we show that mRNA expression is restricted to the thymic medulla, splenic red pulp and sparse cells in the adult brain cortex. In contrast, surprisingly high expression was seen in defined tracts at the base of the cerebellum and in the choroid plexus of day 7 postnatal brain. mCD223:Ig, but not CD4:Ig, fusion proteins stained cells expressing MHC class II molecules. Analysis of mCD223 cell surface expression was performed with a new monoclonal antibody (mAb) that recognizes an epitope in the D2 domain. Although it blocked mCD223 function in vitro, it did not block binding of mCD223 to MHC class II molecules. While very few TCRalpha beta T cells in the spleen and thymus of naive mice express surface mCD223 (<3 %), approximately 18 % TCR gamma delta T cells and approximately 10 % NK cells are positive. This small population of TCRalpha beta T cells are cycling memory T cells (BrdU(+), CD44(hi), CD62L(lo)). In contrast, all T cells express mCD223 2-3 days post activation. This study and the anti-CD223 mAb should greatly assist in the elucidation of CD223 function.
