Lymphatic endothelial cells prime naïve CD8+ T cells into memory cells under steady-state conditions.

Lymphatic endothelial cells (LECs) chemoattract naïve T cells and promote their survival in the lymph nodes, and can cross-present antigens to naïve CD8⁺ T cells to drive their proliferation despite lacking key costimulatory molecules. However, the functional consequence of LEC priming of CD8⁺ T cells is unknown. Here, we show that while many proliferating LEC-educated T cells enter early apoptosis, the remainders comprise a long-lived memory subset, with transcriptional, metabolic, and phenotypic features of central memory and stem cell-like memory T cells. In vivo, these memory cells preferentially home to lymph nodes and display rapid proliferation and effector differentiation following memory recall, and can protect mice against a subsequent bacterial infection. These findings introduce a new immunomodulatory role for LECs in directly generating a memory-like subset of quiescent yet antigen-experienced CD8⁺ T cells that are long-lived and can rapidly differentiate into effector cells upon inflammatory antigenic challenge. Lymphatic endothelial cells (LECs) can cross-present antigen to naïve CD8⁺ T cells, but the significance of this interaction was unclear. Here the authors show that LECs directly induce CD8⁺ T cell differentiation with memory-like phenotypes, migration patterns and transcriptome, which can later be recalled to promote effector immunity and protection from Listeria infection. [ABSTRACT FROM AUTHOR]