Salivary gland NK cells are phenotypically and functionally unique

Area of Science:

• Immunology
• Virology
• Cell Biology

Background:

• Natural killer (NK) cells and CD8(+) T cells are crucial for controlling cytomegalovirus (CMV) infections.
• CMV establishes persistent infections in salivary glands, targeting acinar epithelial cells.

Purpose of the Study:

• To characterize the unique NK cell population residing in the salivary gland.
• To investigate the functional capacity of salivary gland NK cells during murine cytomegalovirus (MCMV) infection.
• To determine the factors contributing to CMV persistence in salivary glands.

Main Methods:

• Characterization of salivary gland NK cells using RORγt reporter and nude mice.
• Analysis of NK cell activation markers, IFN-γ production, and degranulation during MCMV infection.
• Assessment of iNKT and T(reg) cell presence and peripheral NK cell recruitment.

Main Results:

• A distinct NK cell population with mixed mature/immature markers resides in the salivary gland.
• Salivary gland NK cells detect MCMV infection and activate but exhibit impaired IFN-γ production and degranulation.
• iNKT and T(reg) cells are largely absent, and peripheral NK cells are not recruited to the salivary gland during infection.

Conclusions:

• Salivary gland NK cells possess limited effector functions, potentially contributing to viral persistence.
• The lack of peripheral NK cell recruitment to the salivary gland may also facilitate CMV latency.
• These findings highlight intrinsic limitations of salivary gland NK cells in controlling viral infections.