Mutation of conserved MHC class I cytoplasmic tyrosine affects CD8+ T cell priming, effector function, and memory...

Area of Science:

• Immunology
• Molecular Biology
• Cellular Biology

Background:

• The cytoplasmic domain of MHC class I (MHC-I) possesses a conserved tyrosine residue (Y320).
• Previous studies indicated Y320F mutations impair cytotoxic T lymphocyte (CTL) responses due to defective antigen presentation by dendritic cells (DCs).

Purpose of the Study:

• To investigate the post-presentation role of Y320 in T cell priming.
• To explore the impact of Y320 mutations (Y320F and Y320E) on MHC-I function in human and mouse antigen-presenting cells (APCs).

Main Methods:

• Engineered human and mouse APCs to express wild-type (WT) MHC-I, Y320F, or Y320E variants.
• Assessed in vitro T cell priming and expansion.
• Utilized a murine DC vaccine model to evaluate in vivo T cell responses and anti-tumor immunity.

Main Results:

• Y320E-mutated HLA-A*0201 enhanced in vitro priming and expansion of CD8+ T cells, inducing a distinct transcriptional profile.
• The Y320E variant of H-2K^b in a DC vaccine model altered T cell differentiation kinetics.
• In vivo studies showed improved anti-tumor immunity and augmented memory CD8+ T cell responses with the Y320E variant.

Conclusions:

• Y320 phosphorylation of MHC-I influences CD8+ T cell fate and function.
• MHC-I Y320 variants represent a novel strategy for enhancing DC-based cancer immunotherapies.