CD155/CD226-interaction impacts on the generation of innate CD8(+) thymocytes by regulating iNKT-cell differentiation

Area of Science:

• Immunology
• T cell biology
• NKT cell research

Background:

• The CD155 receptor interacts with ligands CD226, CD96, and TIGIT, modulating immune responses.
• Memory CD8(+) T cell generation in the thymus is known to depend on IL-4 produced by invariant NKT (iNKT)2 cells.

Purpose of the Study:

• To investigate the dual function of the CD155-CD226 interaction in the thymus.
• To elucidate the role of this interaction in memory-like CD8(+) T cell generation and dwell time.
• To determine the impact of CD155 and CD226 on invariant NKT (iNKT) cell subtype composition and IL-4 production.

Main Methods:

• Analysis of thymus in BALB/c mice lacking CD155 or CD226.
• Flow cytometry to assess iNKT cell subtype composition (iNKT1, iNKT2, iNKT17).
• Evaluation of IL-4 levels and memory-like CD8(+) T cell populations.

Main Results:

• The CD155-CD226 interaction directly affects memory-like CD8(+) T cell dwell time and indirectly influences their generation.
• Absence of CD155 or CD226 in BALB/c mice leads to a significant shift in iNKT cell subtypes, increasing iNKT1 cells while decreasing iNKT2 and iNKT17 cells.
• This iNKT cell imbalance results in reduced IL-4 levels, creating a phenotype similar to C57BL/6 mice, and this effect is observed in both mouse strains.

Conclusions:

• The CD155-CD226 pathway plays a critical role in maintaining iNKT cell balance within the thymus.
• Dysregulation of this pathway impairs IL-4 production, impacting memory CD8(+) T cell homeostasis.
• These findings highlight a conserved mechanism across different mouse strains affecting T cell immunity.