Detection of Cell Surface Ligands for the γδ TCR Using Soluble TCRs

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Abstract
The natural ligands recognized by γδ TCRs are still largely unknown, in part because immunization does not normally result in Ag-specific γδ T cell responses. Taking advantage of an established ligand for a particular γδ TCR, we demonstrated that a multimerized recombinant form of this γδ TCR can be used like a mAb to specifically detect its own ligand. Using the same approach for more common γδ TCRs whose ligands remain unknown, we detected on certain cell lines molecules that appear to be ligands for three additional γδ TCRs. One of these represents the mouse Vγ6/Vδ1 invariant γδ TCR, which predominates in the female reproductive tract, the tongue, and the lung, and other tissues during inflammation. The second represents the closely related Vγ5/Vδ1 invariant γδ TCR expressed by most epidermal T cells. The third is a Vγ1/Vδ6.3 TCR, representative of a variable type frequently found on lymphoid γδ T cells. We found evidence that ligands for multiple γδ TCRs may be simultaneously expressed on a single cell line, and that at least some of the putative ligands are protease sensitive. This study suggests that soluble versions of γδ TCRs can be as tools to identify and characterize the natural ligands of γδ T cells.