Siglec-7 represents a glyco-immune checkpoint for non-exhausted effector memory CD8+T cells with high functional and metabolic capacities

While inhibitory Siglec receptors are known to regulate myeloid cells, less is known about their expression and function in lymphocytes subsets. Here we identified Siglec-7 as a glyco-immune checkpoint expressed on non-exhausted effector memory CD8+ T cells that exhibit high functional and metabolic capacities. Seahorse analysis revealed higher basal respiration and glycolysis levels of Siglec-7(+) CD8+ T cells in steady state, and particularly upon activation. Siglec-7 polarization into the T cell immune synapse was dependent on sialoglycan interactions in trans and prevented actin polarization and effective T cell responses. Siglec-7 ligands were found to be expressed on both leukemic stem cells and acute myeloid leukemia (AML) cells suggesting the occurrence of glyco-immune checkpoints for Siglec-7(+) CD8+ T cells, which were found in patients' peripheral blood and bone marrow. Our findings project Siglec-7 as a glyco-immune checkpoint and therapeutic target for T cell-driven disorders and cancer.

Automated summary

This study investigates the expression and function of inhibitory Siglec receptors in lymphocyte subsets. The researchers discover Siglec-7 as a glyco-immune checkpoint expressed on non-exhausted effector memory CD8+ T cells, regulating their functional and metabolic capacities. They also find that Siglec-7 polarization into the T cell immune synapse depends on sialoglycan interactions, which prevent actin polarization and effective T cell responses. Siglec-7 ligands are observed on leukemic stem cells and acute myeloid leukemia (AML) cells, suggesting the potential therapeutic role of Siglec-7 in T cell-driven disorders and cancer.