Single-chain MHC class II molecules induce T cell activation and apoptosis

Area of Science:

• Immunology
• Molecular Biology
• Biochemistry

Background:

• MHC class II/peptide complexes on antigen-presenting cells (APCs) are crucial for initiating T cell responses.
• The heterotrimeric structure of MHC class II molecules presents challenges for production and study.

Purpose of the Study:

• To genetically link components of the MHC class II complex into a single polypeptide chain.
• To produce and characterize soluble single-chain (sc) murine class II IA(d) molecules.
• To assess the functionality of sc class II molecules in T cell stimulation.

Main Methods:

• Utilized a recombinant baculovirus-insect cell expression system to produce sc class II molecules.
• Verified molecular conformation through antibody reactivity to conformational epitopes.
• Assessed peptide-specific T cell recognition and stimulation.

Main Results:

• Successfully produced soluble sc murine class II IA(d) molecules, with and without covalently attached peptides.
• Confirmed correct molecular conformation and peptide loading.
• Demonstrated that sc class II molecules effectively stimulate T cell responses, including cytokine release and apoptosis.
• Showed that mammalian cells can express functional sc class II molecules on their surface.

Conclusions:

• Genetically linking MHC class II components into single chains yields functional molecules.
• sc class II/peptide fusion molecules are stable and effective in T cell stimulation.
• This approach facilitates large-scale production for structural analysis and immunotherapeutic applications.