Abstract: Objective To check whether pyruvate kinase isoenzyme type M2 (PKM2) is the TCRγδ’s ligand. Methods By Western blot, the binding of OT3 peptide (the CDR3 region of the δ chain in TCRγδ) with PKM2 was analyzed; with Western blot and immunohistochemistry, the expression of PKM2 in tumor cells and tissues was observed; by flow cytometry and confocal method, PKM2’s location in the tumor cell was tested. The test of immobilized PKM2 expanding γδT cells in vitro and the detection of IFN-γ secreted by PKM2-stimulated γδT cells were used to observe the function of PKM2. Results 1. The binding of PKM2 with OT3 peptide and containing a large number of PKM2 in tumor cells hints that the catching of PKM2 by OT3 peptide from total protein of tumor cells extracts is reasonable and that finding OT3 binding proteins by this method is feasible; 2. PKM2 is widely expressed in tumor cells and tissues, but not expressed on the tumor cell membrane; 3. PKM2 neither expands γδT cells nor stimulates the secretion of IFN-γ from γδT cells in vitro. Conclusion PKM2 is not expressed on the surface of tumor cells, and can’t stimulate activation of γδT cells. PKM2 does not have properties of TCRγδ ligand.

Key words: TCRγδ, PKM2, γδT cells