The Evolving Portrait of γδ TCR Recognition Determinants.

Area of Science:

• Immunology
• T cell biology
• Structural biology

Background:

• Alpha beta T cell receptors (αβ TCRs) survey the body by recognizing antigens (Ags) presented by MHC molecules.
• αβ TCRs typically recognize both the Ag and the Ag-presenting molecule in an 'end-to-end' manner.
• Gamma delta T cells (γδ T cells) possess distinct γδ TCRs with unique antigen recognition capabilities.

Purpose of the Study:

• To review the emerging understanding of γδ TCR recognition modes.
• To contrast γδ TCR antigen recognition with that of αβ TCRs.
• To highlight how γδ TCRs can recognize diverse epitopes, similar to antibodies.

Main Methods:

• Review of structural studies on T cell receptors.
• Comparative analysis of αβ TCR and γδ TCR recognition mechanisms.
• Literature synthesis on antigen presentation and T cell surveillance.

Main Results:

• γδ TCRs can recognize ligands independent of MHC and MHC class I-like restrictions.
• γδ TCR recognition mechanisms can deviate from the corecognition paradigm seen in αβ TCRs.
• Structural insights reveal γδ TCRs can adopt novel docking mechanisms distinct from αβ TCRs.

Conclusions:

• γδ TCRs exhibit a broader and more flexible antigen recognition capacity compared to αβ TCRs.
• The antigen recognition of γδ TCRs is more akin to antibody binding, offering a different mode of immunosurveillance.
• Emerging structural data are crucial for understanding the unique functional properties of γδ T cells.