Distinct dendritic cell cytoskeletal programs dictate synapse architecture and CD8⁺ T cell fate

Area of Science:

• Immunology
• Cell Biology
• T cell activation

Background:

• Dendritic cell (DC) activation of CD8+ T cells at the immunological synapse is crucial for adaptive immunity.
• The structural organization of the DC side of the synapse and its influence on T cell differentiation remain unclear.

Purpose of the Study:

• To investigate the structural organization of dendritic cell synapses and its functional consequences on T cell fate.
• To determine the role of CD70 expression in dictating dendritic cell synapse morphology and T cell programming.

Main Methods:

• Utilized bone marrow-derived dendritic cells (BMDCs) as a model system.
• Characterized distinct dendritic cell subpopulations based on synapse formation capacity and morphology.
• Assessed the impact of CD70 expression levels on synapse architecture and T cell differentiation profiles.

Main Results:

• Identified two stable BMDC subpopulations forming morphologically distinct synapses: 'firework' (CD70-high) and 'pancake' (CD70-low).
• CD70-high BMDCs utilize a filopodia-based cytoskeletal program to form spiky synapses, priming potent, terminally differentiated Tc1 effector cells.
• CD70-low BMDCs form smooth synapses, secrete IL-6, and generate memory T cells with a Tc17-like profile and strong recall responses.

Conclusions:

• Dendritic cell synapse architecture is a critical determinant of T cell fate and immunological outcomes.
• Differential CD70 expression governs synapse structure, leading to distinct T cell effector and memory responses.
• Linking physical cell organization to specific immune functions provides new insights into adaptive immunity regulation.