A Streamlined and Time-Saving Approach to Generate HLA-DR15 MHC Class II Tetramers via In Vivo Biotinylation

Area of Science:

• Immunology
• Molecular Biology
• Biochemistry

Background:

• Peptide-loaded major histocompatibility complex (pMHC) class II tetramers are crucial for identifying antigen-specific T cells.
• Conventional methods for generating pMHC class II tetramers are multi-step, time-consuming, and result in protein loss.

Purpose of the Study:

• To develop an optimized and efficient protocol for generating peptide-loaded MHC class II tetramers.
• To streamline the production process, reduce handling steps, and improve protein yield and reproducibility.

Main Methods:

• Co-expression of MHC monomers and BirA biotin ligase in Expi293F T cells for in vivo biotinylation.
• Utilizing a thrombin-cleavable class II-associated invariant chain peptide (CLIP) for flexible antigenic peptide loading.
• Purification, peptide loading, and assembly into fluorescent tetramers via streptavidin conjugation.

Main Results:

• Achieved one-step in vivo biotinylation, eliminating the need for purchased BirA enzyme and saving approximately 16 hours.
• Enabled flexible CLIP-based peptide exchange without re-cloning or re-expression of MHC molecules.
• Produced validated antigen-specific tetramers suitable for sensitive T cell detection via flow cytometry.

Conclusions:

• The streamlined workflow significantly improves the efficiency, yield, and reproducibility of pMHC class II tetramer generation.
• The developed method supports sensitive detection and isolation of antigen-specific T cells for applications in immunogenicity studies, vaccine development, and autoimmune research.
• This optimized protocol provides a valuable tool for advancing immunological research and therapeutic development.