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A Method For Production of Recombinant mCD1d Protein in Insect Cells.
Published on: December 11, 2007
CD1d1 displayed on cell size beads identifies and enriches an NK cell population negatively regulated by CD1d1
Michael M S Huang1, Peter Borszcz, Stephane Sidobre
1Department of Medical Microbiology and Immunology, Faculty of Medicine, University of Alberta, Edmonton, Alberta, Canada.
Insights
Natural killer (NK) cells possess a novel inhibitory receptor that binds to CD1d1 molecules. This interaction suppresses NK cell activity, offering new insights into immune regulation and NK cell receptor-ligand dynamics.
Area of Science:
- Immunology
- Cellular Biology
- Molecular Interactions
Background:
- Natural killer (NK) cells are crucial for innate immunity, eliminating infected or cancerous cells.
- NK cell activity is regulated by inhibitory receptors interacting with MHC class I molecules.
- CD1d1, a class I-like molecule, presents glycolipids to NKT cells, but its role in NK cell regulation was unclear.
Purpose of the Study:
- To investigate the interaction between IL-2-activated NK cells and CD1d1.
- To identify a potential CD1d1-specific inhibitory receptor on NK cells.
- To elucidate the mechanism of CD1d1-mediated inhibition of NK cell cytotoxicity.
Main Methods:
- Utilized cell size beads coated with CD1d1 to assess binding with IL-2-activated mouse NK cells.
- Compared cytotoxicity of CD1d1-binding NK cell subsets versus non-binding subsets.
- Employed an antibody to block NKT cell recognition of CD1d1 to assess its effect on NK cell inhibition.
Main Results:
- A subset of IL-2-activated NK cells specifically bound to CD1d1-coated beads.
- NK cell cytotoxicity was significantly inhibited by CD1d1 in the CD1d1-binding subset.
- Antibody blockade of NKT cell recognition reversed CD1d1-mediated NK cell inhibition.
Conclusions:
- NK cells possess a functional, low-affinity inhibitory receptor for CD1d1.
- This receptor mediates physical interaction and functional inhibition of NK cells by CD1d1.
- Ligand display on beads offers a method to study NK cell receptor-ligand interactions, especially low-affinity ones.
Abstract:
NK cells destroy microbe-infected cells while sparing healthy cells, and are controlled, in part, by inhibitory receptors specific for class I Ag-presenting molecules. CD1d1, a beta(2)-microglobulin-associated class I-like molecule, binds glycolipids and stimulates NKT cells. We previously demonstrated that target cell lysis by IL-2-activated mouse NK cells is inhibited by target cell expression of CD1d1, suggesting that IL-2-activated NK cells may express a CD1d1-specific inhibitory receptor. We now report that a significant subset of mouse IL-2-activated NK cells specifically binds cell size beads displaying either naturally expressed or recombinant CD1d1. In contrast, although tetramers of soluble recombinant CD1d1 loaded with alpha-galactosylceramide identify NKT cells, binding of this reagent to resting or IL-2-activated NK cells was undetectable, even with activated NK cells sorted with CD1d1 beads. Cytotoxicity by the CD1d1 bead-separated NK subset was strongly inhibited by CD1d1, compared with the NK cell subset not bound to CD1d1 beads. An Ab that blocks NKT cell recognition of CD1d1 also reverses CD1d1 inhibition of NK lysis, suggesting that TCRs of NKT cells and NK inhibitory receptor(s) may interact with a similar site on CD1d1. These results provide direct evidence for a physical interaction of NK cells with CD1d1, mediated by a functional, CD1d1-specific low-affinity inhibitory NK receptor. Display of ligands on cell size beads to maximize multivalent interaction may offer an alternative approach to examine NK cell receptor-ligand interactions, particularly those of lower expression and/or lower affinity/avidity that may go undetected using tetrameric reagents.
