An MR1-specific nanobody capable of blocking MR1T cell activation

Area of Science:

• Immunology
• Molecular Biology
• Biochemistry

Background:

• MR1 is an MHC class I-like molecule presenting metabolites to T cells, crucial in immunity but poorly understood.
• Mechanisms of MR1 antigen loading and trafficking are unclear due to a lack of specific molecular tools.
• MR1's role in microbial infection, inflammation, and tumor immunity is established, yet its fundamental biology requires further investigation.

Purpose of the Study:

• To develop and characterize a novel molecular tool for dissecting MR1 biology.
• To create a high-affinity nanobody targeting MR1 for precise functional manipulation.
• To investigate MR1's role in T cell activation and antigen presentation.

Main Methods:

• Development of a high-affinity anti-MR1 nanobody (MR1Nb1).
• Characterization of MR1Nb1 binding kinetics and affinity using ELISA and BLI.
• Epitope mapping of MR1Nb1 on MR1 via Hydrogen-Deuterium Exchange Mass Spectrometry (HDX-MS).
• Functional assays assessing MR1Nb1's ability to block MR1-T cell activation and stain MR1-ligand complexes.

Main Results:

• MR1Nb1 exhibits high affinity (1.6 nM KD) for MR1.
• Epitope mapping provided insights into MR1Nb1's mechanism of blocking T cell activation.
• MR1Nb1 effectively blocked MR1-T cell activation induced by microbial infection and synthetic ligands.
• MR1Nb1 successfully stained MR1-ligand complexes on cell surfaces via flow cytometry.

Conclusions:

• MR1Nb1 is a versatile and powerful molecular probe for studying MR1 biology.
• The nanobody enables precise investigation of MR1's function in antigen presentation and T cell activation.
• This tool facilitates deeper understanding of MR1's broader roles in immunity, infection, and inflammation.