Cytosolic entry controls CD8+-T-cell potency during bacterial infection

Area of Science:

• Immunology
• Microbiology
• Cellular Biology

Background:

• Host immunoreceptor interactions shape innate immune responses during infection.
• The impact of these signals on adaptive T-cell response quality is not well understood.

Purpose of the Study:

• To investigate the role of microbial phagosomal escape in shaping adaptive T-cell responses.
• To determine the mechanisms by which T-cell priming influences protective immunity.

Main Methods:

• Utilized an engineered strain of Listeria monocytogenes that infects cells but does not escape the phagosome.
• Assessed T-cell memory formation, expansion, and effector function.
• Analyzed dendritic cell activation and CD40 signaling.

Main Results:

• Engineered L. monocytogenes induced long-lived memory T cells with secondary expansion and effector function.
• These memory T cells were incapable of providing protective immunity.
• Phagosomal escape was essential for dendritic cell activation and CD40 signaling, crucial for protective CD8+ T-cell responses.

Conclusions:

• Microbial phagosomal escape is critical for eliciting protective CD8+ T-cell immunity.
• Escape is required for optimal dendritic cell activation and CD40 signaling, not merely antigen presentation.
• The cellular context established during T-cell priming dictates protective capacity.