Applications of major histocompatibility complex class I molecules expressed as single chains

Area of Science:

• Immunology
• Molecular Biology
• Structural Biology

Background:

• Optimal CD8 T-cell responses depend on stable Major Histocompatibility Complex (MHC) class I/peptide complexes.
• Pathogens can interfere with MHC class I expression and peptide loading, leading to immune evasion.
• Current methods for presenting MHC class I/peptide complexes have limitations in stability and immunogenicity.

Purpose of the Study:

• To engineer and characterize single-chain trimers (SCTs) of MHC class I molecules for enhanced immunogenicity and stability.
• To evaluate the potential of SCTs as immunotherapeutic agents against pathogens and tumors.
• To assess the resistance of SCTs to immune evasion mechanisms.

Main Methods:

• Engineering of single-chain trimers (SCTs) by linking peptide, beta2-microglobulin (beta2m), and MHC class I heavy chain (K(b)) with flexible linkers.
• Characterization of SCT stability at the cell surface.
• Immunization with DNA encoding SCTs and assessment of antibody and T-cell responses.
• Testing SCT resistance to immune evasion proteins (e.g., mK3).

Main Results:

• VSVp-beta2m-K(b) SCTs demonstrated remarkable cell surface stability.
• Immunization with SCT DNA elicited complex-specific antibodies and activated cytotoxic T-lymphocytes.
• SCTs were resistant to peptide displacement and immune evasion by mK3.
• SCTs effectively primed CD8 T-cells in vivo that recognized native MHC class I molecules.

Conclusions:

• Engineered MHC class I SCTs offer a stable and immunogenic platform for T-cell activation.
• SCTs exhibit resistance to pathogen-mediated immune evasion strategies.
• SCTs hold significant therapeutic potential for prophylactic and therapeutic interventions in infectious diseases and cancer immunotherapy.