CD86 has sustained costimulatory effects on CD8 T cells

Area of Science:

• Immunology
• T cell biology
• Autoimmunity

Background:

• CD80 and CD86 are key costimulatory molecules for T cell activation.
• Studying their individual in vivo roles is challenging due to coordinated upregulation on antigen-presenting cells (APCs).

Purpose of the Study:

• To investigate the distinct in vivo roles of CD80 and CD86 in T cell activation using genetically modified mouse models.
• To assess the impact of CD80 and CD86 costimulation on diabetes onset and progression as a readout for cytotoxic T cell activity.

Main Methods:

• Generation of transgenic mice expressing rat insulin promoter (RIP)-CD80 and RIP-CD86 on NOD and NOD.scid backgrounds.
• Utilizing diabetes onset and transfer as a measure of cytotoxic T cell activation.
• In vitro assessment of T cell cytotoxicity, proliferation, and cytokine secretion.

Main Results:

• NOD-RIP-CD80 mice exhibited accelerated spontaneous diabetes onset and greater diabetes transfer compared to NOD-RIP-CD86 mice.
• CD86 costimulation demonstrated sustained in vivo responses, evidenced by recurrent diabetes and successful adoptive transfer.
• In vitro, CD80 enhanced CD8 T cell cytotoxicity, proliferation, and cytokine secretion more than CD86.
• Increased expression of inhibitory molecules CTLA-4 and PD-1 was observed with both CD80 and CD86 costimulation (CD80 > CD86).
• T cells stimulated by CD80 were more susceptible to suppression by regulatory T cells.

Conclusions:

• CD80 elicits a potent initial T cell response, while CD86 promotes sustained immune activity, even without continuous costimulation.
• These distinct functions have significant implications for the therapeutic engineering of costimulatory molecules to modulate immune responses.