As a unique lymphocyte population and a subset of T cells, human γδ T cells express the γδ T cell receptor (TCR) and they have a specific tissue distribution and antigen (Ag) recognition pathway. To achieve early immunity against infection, γδ T cells take part in many pathways, such as soluble proinflammatory molecules, influenza viruses, chemokines, rapid cytotoxicity or crosstalk with other cell types that are involved. Besides, a previous study has demonstrated that γδ T cells from patients infected with HIV showed antiviral potential via their cytolytic functions. Thus, the most important mechanism of γδ T cell-mediated immune responses to infection is the direct killing of infected cells or invasive pathogens.

Many pathways are involved in the cytotoxicity of γδ T cells, such as Fas‑Fas ligand interactions, and the secretion of granzyme B, perforin, and granzyme M. Moreover, in several diseases, defects in these cytotoxic mechanisms lead to the suppression of γδ T cell activity. But researches have shown that stimulation with phosphoantigen promotes the function of γδ T cells and may inhibit HIV infection via cell‑release antiviral factors.

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