Objective    To construct an eukaryotic expression vector that expresses MHC-Ⅰ- fluorescin tetramer and then induce the protein to express and be purified in order to detect antigenic specificity T cell more conveniently.     Methods    The eukaryotic expression vector of a fusion protein was constructed by linking the target gene fragment with the sequence of the sKb-ZsGreen-6 His Tag by molecular cloning technique

and then the recombinant was transfected into 293FT to express the protein. Ni-affinity chromatography was used to purify the objective protein from the transfected cell lysis. Flow cytometry was used to detect the existence of B3Z cells pretreated with the mixture of our obtained protein

β2 microglobulin and peptide OVA (4 μg:4 μg:2.77 μg in 100 μl PBS).     Results    An eukaryotic expression vector of MHC-Ⅰ- fluorescin tetramer was constructed successfully

and the protein was expressed in 293FT cells and purified. The mixture treated B3Z cells showed 88.3% green fluorescence in compared with those untreated cells.     Conclusion    The MHC-Ⅰ- fluorescin tetramer is produced and purified. The tetramer is recognized by B3Z cells after bounding to β2 microglobulin and peptide OVA

and it can be used as a convenient method for detecting antigenic specificity T cells.