SIRPα is An Inhibitory Receptor That Regulates NK Cell Activation and Function

Area of Science:

• Immunology
• Virology
• Cell Biology

Background:

• Signal regulatory protein alpha (SIRPα) is an inhibitory receptor on myeloid cells.
• SIRPα is increasingly recognized on natural killer (NK) cells, particularly in cancer research.
• Its role in NK cell function during viral infections remains largely unexplored.

Purpose of the Study:

• To investigate the function of SIRPα in NK cells during viral infection.
• To elucidate the impact of SIRPα on NK cell activation and cytotoxicity.
• To understand the consequences of SIRPα deficiency on adaptive immunity and viral control.

Main Methods:

• Utilized SIRPα knockout mice and lymphocytic choriomeningitis virus (LCMV) infection model.
• Employed flow cytometry to analyze NK cell populations and activation markers.
• Conducted in vivo killing assays and molecular analyses to assess NK cell function and signaling pathways.

Main Results:

• SIRPα expression was upregulated on NK cells during LCMV infection.
• SIRPα deficiency led to increased NK cell proportion, activation, and cytotoxic function.
• Loss of SIRPα resulted in CD8+ T cell depletion, impaired viral control, and increased immunopathology.
• NK cell depletion in SIRPα-deficient mice partially restored T cell immunity and viral clearance.

Conclusions:

• SIRPα acts as a critical inhibitory receptor regulating NK cell effector functions.
• Loss of SIRPα enhances NK cell activity but detrimentally affects adaptive antiviral immunity via CD8+ T cell depletion.
• SIRPα plays a dual role in balancing NK cell activation and adaptive immune responses during viral infections.