Dimerization of soluble disulfide trap single-chain major histocompatibility complex class I molecules dependent on...

Area of Science:

• Immunology
• Molecular Biology
• Biochemistry

Background:

• Major histocompatibility complex (MHC) class I molecules present peptide epitopes to CD8(+) T cells, crucial for adaptive immunity.
• Stable peptide-MHC interactions are essential for effective CD8(+) T cell expansion.
• Single-chain MHC class I (scMHC I) molecules offer enhanced stability by covalently linking peptide, β(2)-microglobulin, and MHC heavy chain.

Purpose of the Study:

• To develop a system for in vitro expansion of antigen-specific CD8(+) T cells using novel scMHC I constructs.
• To investigate the role of disulfide bonds in stabilizing scMHC I molecules for improved peptide anchoring.
• To assess the therapeutic potential of scMHC I molecules presenting leukemia-associated T cell epitopes.

Main Methods:

• Construction and expression of scMHC I molecules, including disulfide trap variants, in eukaryotic cells.
• Analysis of scMHC I molecule stability, folding, and dimerization using conformation-specific antibodies.
• Comparison of soluble scMHC I with full-length transmembrane-anchored scMHC I molecules.

Main Results:

• Soluble disulfide trap scMHC I molecules unexpectedly underwent peptide-dependent homodimerization.
• These homodimers were stable and recognized as correctly folded by specific antibodies.
• Dimerization was not observed in full-length, transmembrane-anchored scMHC I molecules.
• Peptide binding affinity was identified as a key factor for efficient MHC class I folding.

Conclusions:

• scMHC I molecules, particularly disulfide trap variants, show promise for enhancing T cell responses.
• Peptide binding affinity is a critical determinant of MHC class I folding and stability.
• The observed dimerization of soluble scMHC I may have implications for their application in immunotherapy.