Graduate Teaching Assistant University of Vermont Larner College of Medicine Burlington, Vermont, United States
Disclosure(s):
Conor Dempsey: No relevant disclosure to display
Introduction/Rationale: γδ T cells are evolutionarily conserved innate-like T cells that have been implicated in infectious disease, autoimmunity, and cancer. While there is growing appreciation of the roles these cells play in shaping the immune response, our understanding of γδ T cell biology has lagged behind that of their iNKT and MAIT cell counterparts. This gap in understanding can largely be attributed to our poor understanding what T cell receptors recognize. We recently reported that a significant fraction of IFN--producing V4 T cells are characterized by the preferential usage of a Vγ4Vδ7 TCR. Here, we set out to identify and characterize the binding partners of the Vγ4Vδ7 TCR under normal homeostatic conditions.
Methods: A recombinant soluble Vγ4Vδ7 TCR tetramer was produced and used to screen and identify Vγ4Vδ7-specific populations from normal mouse tissues using flow cytometry under different binding conditions.
Results: When tetramer staining was conducted at 4C, we found that Vγ4Vδ7 TCR bound to a rare population of B cells in both the spleen and lungs of B6 mice. Interestingly, however, when tetramer staining was conducted at 23oC or 37 oC, we found that Vγ4Vδ7 TCR bound to a wide variety of cells in the same tissues, while an irrelevant human TCR exhibited no binding under similar conditions. Vγ4Vδ7 tetramer binding to cells was inhibited at both temperatures through addition of unlabeled Vγ4Vδ7 TCR monomer, and permeabilization of cells prior to staining resulted in a significant increase in Vγ4Vδ7 TCR staining.
Conclusion: Taken together, the data suggest the presence of an intracellular Vγ4Vδ7 TCR ligand that is broadly distributed among a wide variety of cell types, and that a small subset of B cells expresses this ligand on the cell surface. These data are consistent with a model in which the Vγ4Vδ7 TCR recognizes a conserved intracellular ligand that may be translocated to the cell surface under specific conditions.
