(864) Activating systemic immunity through engineered lymph node-homing T cells

Introduction/Rationale: Lymph nodes (LNs) serve as the critical education centers of adaptive immunity to combat pathogens while simultaneously protecting host tissues through peripheral tolerance induction. LNs are often co-opted by tumors to induce tumor-specific immune tolerance yet are also key sites of immunotherapy response. Here, we aim to develop a cell therapy capable of reeducating systemic anti-tumor immunity within LNs.

Methods: Naïve T cells continuously circulate between blood and LNs through a process that is dynamically regulated by multiple cell surface receptors. We have harnessed these mechanisms by engineering T cells to constitutively express the cell surface protein responsible for initiating the LN-homing cascade, L-selectin. We transduce T cells using viral vectors encoding a wild-type (WT L-sel) or engineered L-selectin variant (L-sel mut). To assess selective LN-homing capacity, we adoptively transfer our engineered cells into mice and subsequently quantify tissue accumulation by flow cytometry.

Results: Flow cytometry of cell surface L-selectin expression reveals a 6-fold increase on our engineered T cells compared to control cells. Upon PMA/Ionomycin stimulation, 91.2% of L-sel mut cells maintain cell surface expression of L-selectin in comparison to 28.9% of WT L-sel and 7.8% of control T cells. Furthermore, adoptive transfer of equal proportions of control, WT L-sel, and L-sel mut T cells yielded selective accumulation of the engineered cells within LNs.

Conclusion: By harnessing the intrinsic mechanisms that govern T cell LN-homing, we have engineered T cells that maintain expression of L-selectin on the cell surface, endowing them with a propensity for LN-homing. By combining these technologies with tumor recognition domains and armoring approaches, these therapies have the potential to elicit anti-tumor immunity within LNs and systemically.