CD28-CD80 interactions control regulatory T cell motility and immunological synapse formation

Area of Science:

• Immunology
• Cellular Biology

Background:

• Regulatory T cells (Tregs) are crucial for maintaining immune tolerance.
• Tregs interact with dendritic cells (DCs) to regulate immune responses.
• Tregs downmodulate costimulatory molecules on DCs, influencing T cell activation.

Purpose of the Study:

• To investigate the dynamic interactions between Tregs and DCs.
• To understand how costimulatory molecules, like CD80, affect Treg-DC conjugates.
• To elucidate the mechanisms underlying Treg-DC synapse formation and motility.

Main Methods:

• Utilized supported planar bilayers to model Treg-DC interactions.
• Analyzed Treg-DC conjugate stability and morphology.
• Employed blocking antibodies to investigate the roles of CTLA-4 and CD28-CD80 interactions.

Main Results:

• Tregs formed stable conjugates with DCs prior to CD80 downregulation.
• Antigen recognition in the absence of costimulation led to motile Tregs with a polarized 'kinapse' phenotype.
• High CD80 concentrations induced stationary, symmetrical synapses between Tregs and DCs.
• CTLA-4 blockade prevented CD80 downregulation, while CD28-CD80 interactions modulated Treg motility.

Conclusions:

• Treg-DC interactions are dynamic and influenced by costimulatory signals.
• Treg motility is regulated by CD80 expression levels on DCs.
• The findings support a model where Tregs adapt their behavior based on the immunological microenvironment.