Molecular mechanisms underlying the modulation of T-cell proliferation and cytotoxicity by immobilized CCL21 and ICAM1

A major challenge in adoptive cancer immunotherapy is the effective balance between the proliferation and cytotoxic capacity of the effector CD8+ T-cells. In this study we explored the molecular mechanisms whereby a “synthetic immune niche” (SIN), composed of immobilized CCL21 and ICAM1, modulates the interplay between these two cellular properties. Temporal phenotypic profiling of OVA-specific murine T-cells revealed major differences in the response to the SIN stimulation following antigen-specific and non-specific activation. Thus, SIN treatment enhanced both the expansion and cytotoxicity of cells activated by OVA-loaded DCs, at day 4, while, similar treatment of cells activated by anti CD3/CD28-conjugated beads dramatically enhanced the cells’ expansion, but unexpectedly blocked their cytotoxicity, which fully recovered only on day 7. Molecular profiling suggest that upregulation of cytotoxic gene signatures drive the SIN effect following DC activation, while down-regulation of exhaustion and pro-apoptotic genes optimize the proliferation-cytotoxicity balance in the beads-activated cells.