Classical Flt3L-dependent dendritic cells control immunity to protein vaccine

Area of Science:

• Immunology
• Vaccine Biology
• Cellular Immunology

Background:

• Dendritic cells (DCs) are crucial for initiating adaptive immunity.
• The prevailing view is that migratory DCs (migDCs) and lymphoid-resident classical DCs (cDCs) collaborate in lymph nodes (LNs) to prime T cells.
• The role of DCs in subcutaneous immunity requires further elucidation.

Purpose of the Study:

• To investigate the role of Fms-like tyrosine kinase 3 ligand (Flt3L) in subcutaneous immunity.
• To determine the distinct contributions of migDCs and cDCs in vaccine responses.
• To uncover the regulatory mechanisms governing DC function in adaptive immunity.

Main Methods:

• Flt3 deletion models in mice.
• Assessment of T cell and humoral immunity following immunization.
• Analysis of DC numbers and antigen capture capacity.
• Transcriptomic analysis of migDC subsets in mouse and human skin.

Main Results:

• Subcutaneous immunity is dependent on Flt3L, with Flt3 deletion reducing T cell responses by 50%.
• Flt3L enhances T cell and humoral immunity, increasing numbers and antigen capture of both migDCs and LN-resident cDCs.
• Immunity is controlled by cDCs and actively suppressed by migDCs; deleting Langerin(+) DCs or blocking DC migration improves immunity.
• Skin migDC subsets in mice and humans share immune-suppressing gene expression profiles.

Conclusions:

• Protective immunity to protein vaccines is orchestrated by Flt3L-dependent, LN-resident cDCs.
• Migratory DCs play an unexpected immune-regulatory role, tempering adaptive immune responses.
• Understanding these DC subset dynamics is critical for developing effective vaccine strategies.