Hypoimmunogenic HLA-E Single Chain Inhibits Alloreactive Immune Responses

Area of Science:

• Immunology
• Cell Therapy
• Molecular Engineering

Background:

• Allogeneic chimeric antigen receptor (CAR) T cells face immune rejection by recipients, limiting their efficacy.
• Recipient immune responses, particularly from CD8+ T cells and NK cells, can reduce CAR T cell persistence.
• Strategies are needed to overcome immune barriers for universal donor CAR T cell therapies.

Purpose of the Study:

• To engineer hypoimmunogenic CAR T cells resistant to recipient immune rejection.
• To enhance the in vivo persistence and therapeutic efficacy of allogeneic CAR T cells.
• To develop a novel HLA-E-based single-chain receptor to restore NK cell tolerance.

Main Methods:

• Generated HLA class I-deficient T cells by disrupting beta-2 microglobulin.
• Engineered T cells to express a disulfide trap HLA-E4 (dtHLA-E4) molecule for NK cell tolerance.
• Incorporated mutations into the dtHLA-E4 molecule's alpha-3 domain to reduce CD8+ T cell recognition.

Main Results:

• The optimized dtHLA-E4 molecule showed increased surface expression and enhanced NK cell inhibition.
• dtHLA-E4 abrogated CD8-dependent T cell recognition while preserving NK cell inhibitory function.
• Peptides from HLA-A and HLA-C allotypes maximized NK cell inhibition and minimized NKG2C+ NK cell activation.

Conclusions:

• Systematic construction of a hypoimmunogenic dtHLA-E4 molecule successfully reduced T cell immunogenicity.
• This engineered CAR T cell strategy overcomes NK cell 'missing-self' recognition.
• The developed hypoimmunogenic CAR T cells show promise for improved persistence in allogeneic settings.