Tumour-reactive heterotypic CD8 T cell clusters from clinical samples

Area of Science:

• Immunology
• Oncology
• Cell Biology

Background:

• CD8+ T cell proximity to tumor cells correlates with anti-tumor immunity.
• The existence and functional significance of isolated T cell-tumor cell clusters are not well understood.

Purpose of the Study:

• To investigate the presence and characteristics of heterotypic clusters of CD8+ T cells and tumor cells in human melanoma metastases.
• To assess the functional potential and therapeutic utility of T cells isolated from these clusters.

Main Methods:

• Conventional and imaging flow cytometry to isolate heterotypic clusters.
• Single-cell RNA-sequencing to analyze T cell gene expression.
• Ex vivo expansion and functional assays of T cells from clusters.
• Adoptive cell transfer in mice to evaluate anti-tumor efficacy.

Main Results:

• Heterotypic clusters of CD8+ T cells, tumor cells, and antigen-presenting cells (APCs) were isolated from all tested melanoma metastases.
• T cells within clusters showed enrichment for tumor reactivity and exhaustion signatures, with increased TCR clonality.
• Expanded T cells from clusters exhibited significantly enhanced killing activity against autologous melanomas and improved control in mouse models.
• T cells from clusters demonstrated increased infiltration and activation in vivo.

Conclusions:

• Tumor-reactive CD8+ T cells are enriched in functional, isolatable heterotypic clusters with tumor cells and/or APCs.
• These T cell clusters represent a valuable source for understanding tumor-immune interactions and hold therapeutic potential.