Reprogramming T cell fate through antibody-mediated galectin-1 blockade.

Galectins, a family of highly conserved β-galactoside-binding proteins, favor tumor progression by modulating multiple hallmarks of cancer. Galectin-1 (GAL1), a prototype member of this family, plays essential roles in both tumor immunosuppression and angiogenesis through interactions with glycosylated receptors on the surface of immune and vascular cells. Targeting GAL1 inhibits tumor growth and metastasis by enhancing antitumor immunity and preventing aberrant angiogenesis in several experimental models. Therefore, strategies aimed at blocking this multifunctional glycan-binding protein (GBP) hold promise for cancer therapy. Potential inhibitory agents include glycan-based small molecule inhibitors, peptides and peptidomimetics, aptamers, and neutralizing monoclonal antibodies. In this context, establishing a toolbox of strategies to evaluate their function-blocking activity is crucial. Since GAL1 induces apoptosis of activated T cells, its determination provides a functional readout of GAL1 activity. We describe here a protocol for a T-cell death inhibition assay to assess the blocking capacity of galectin-targeting agents, using a fully human anti-GAL1 monoclonal antibody as a model.