Divided by the T-cell receptor (TCR) expressed on the cell surface, T lymphocytes are generally categorized into αβ T cells and γδ T cells. The human γδ T cell is a minor population of T lymphocytes carrying a distinctive γδ T-cell receptor (γδ-TCR). Although only accounting for ~5% of the total T cells, γδ T cells play an important function in both innate and adaptive immune responses.