Photoaffinity antigens for human gammadelta T cells.

Area of Science:

• Immunology
• T cell receptor signaling

Background:

• Vgamma2Vdelta2 T cells are a major human gammadelta T cell subset.
• They recognize nonpeptide prenyl pyrophosphates like HMBPP and isopentenyl pyrophosphate.
• Evidence suggests a presenting molecule, but its identity remains unknown due to difficulties in antigen-presenter complex formation.

Purpose of the Study:

• To identify the antigen-presenting molecule for Vgamma2Vdelta2 T cell recognition of nonpeptide prenyl pyrophosphates.
• To characterize the properties of this novel antigen-presenting molecule.

Main Methods:

• Utilized photoaffinity analogues of HMBPP (m/p-BZ-(C)-C(5)-OPP) to crosslink to antigen-presenting cells.
• Tested antigen presentation using various tumor cell lines, including those deficient in MHC class I, MHC class II, beta(2)-microglobulin, and CD1.
• Investigated competitive inhibition of antigen presentation using isopentenyl pyrophosphate and its analogs.

Main Results:

• Photoaffinity analogues of HMBPP successfully crosslinked to and were presented by tumor cell lines.
• Antigen presentation occurred in cell lines lacking classical antigen-presenting molecules (MHC I, MHC II, beta(2)-microglobulin, CD1).
• Isopentenyl pyrophosphate inhibited the presentation of the HMBPP analogue, indicating binding to the same molecule.

Conclusions:

• A novel, widely distributed, and nonpolymorphic antigen-presenting molecule presents nonpeptide prenyl pyrophosphates to Vgamma2Vdelta2 T cells.
• This molecule is distinct from MHC class I, MHC class II, and CD1.
• This discovery advances understanding of innate-like T cell recognition pathways.