The T cell
immunoglobulin and
mucin-domain containing-3 (TIM-3) receptor has gained significant attention as a promising target for
cancer immunotherapy. The inhibitory effect of T cells by TIM-3 is mediated through the interaction between TIM-3 and its
ligands.
Ligand-blocking anti-TIM-3
antibodies possess the potential to reactivate
antigen-specific T cells and augment anti-
tumor immunity. However, the precise
ligand-receptor interactions disrupted by the administration of TIM-3 blocking Abs have yet to be fully elucidated. In this study, we have developed a panel of
monoclonal antibodies targeting human TIM-3, namely MsT001, MsT065, MsT229, and MsT286. They exhibited high sensitivities (10 pg/mL) and affinities (3.70 × 10-9 to 4.61 × 10-11 M) for TIM-3. The TIM-3
antibodies recognized distinct
epitopes, including linear
epitopes (MsT001 and MsT065), and a conformational
epitope (MsT229 and MsT286). Additionally, the MsT229 and MsT286 displayed reactivity towards cynomolgus TIM-3. The interactions between TIM-3/Gal-9, TIM-3/
HMGB-1, and TIM-3/CEACAM-1 disrupt the binding of MsT229 and MsT286, while leaving the binding of MsT001 and MsT065 unaffected. The inhibitory effect on the interaction between Gal-9 and TIM-3 was found to be dose-dependently in the presence of either MsT229 or MsT286. The findings suggested that the involvement of conformational
epitopes in TIM-3 is crucial for its interaction with
ligands, and we successfully generated novel anti-TIM-3 Abs that exhibit inhibitory potential. In conclusion, our finding offers valuable insights -on the comprehension and targeting of human TIM-3.