Characterization of T cell receptors (TCRs) involved in immune responses is important to the design of tumor immunotherapy and vaccine. The specificity of the interaction between the TCR heterodimer and its peptide-MHC ligand is primarily derived from the highly variable CDR3 regions juxtaposed with the TCR alpha and TCR beta chains, and obtaining the pairing sequences of these regions is the criteria for the functional definition of TCR. Current methods for identifying TCRs in T cell populations are using high throughput TCR single cell sequencing.