Evidence that the KIR2DS5 gene codes for a surface receptor triggering natural killer cell function

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• Killer immunoglobulin-like receptors (KIRs) are crucial regulators of natural killer (NK) cell activity.
• The specific functions and expression patterns of certain KIRs, like KIR2DS5, remain incompletely understood.
• Developing specific reagents is essential for dissecting KIR-mediated signaling pathways.

Purpose of the Study:

• To generate a novel monoclonal antibody (mAb) targeting specific KIR2D receptors, including KIR2DS5.
• To investigate the expression and function of KIR2DS5 on NK cells.
• To elucidate the signaling mechanisms associated with KIR2DS5 engagement.

Main Methods:

• Immunization with NK cells and screening on KIR-expressing transfectants to generate mAb DF200.
• Analysis of peripheral blood NK cells and NK cell clones.
• Co-transfection and co-immunoprecipitation assays to study protein associations.
• Functional assays measuring cytotoxicity and cytokine release upon mAb engagement.
• Binding assays using soluble KIR2DS5-Fc fusion protein with HLA-C expressing cells.

Main Results:

• A novel mAb, DF200, was generated, recognizing KIR2DL1/L2/L3, KIR2DS1/S2, and KIR2DS5.
• KIR2DS5 is expressed on distinct subsets of NK cells and its engagement by DF200 induces cytotoxicity and cytokine release.
• KIR2DS5 associates with the DAP12 signaling polypeptide.
• Soluble KIR2DS5-Fc did not bind to various HLA-C alleles, suggesting peptide-dependent recognition.

Conclusions:

• The mAb DF200 is a valuable tool for studying KIR2D receptors, particularly KIR2DS5.
• KIR2DS5 is a functional receptor on human NK cells, capable of mediating effector functions via DAP12 signaling.
• KIR2DS5's interaction with HLA-C may be peptide-specific or indirect, requiring further investigation.