Protective Role of γδ T Cells in Different Pathogen Infections and Its Potential Clinical Application

Figure 1

γδ T cells recognize antigens. Diverse subtypes of γδ T cells could recognize different types of antigens. γδ T cells (both Vδ1 and Vδ2) could recognize stress-induced molecules MICA/B and ULBPs which are expressed in cancer and transformed and infected cells in a NKG2D-dependent manner. Vδ1 T cells could recognize bacteria-derived antigens (including lipids and glycolipid) via MHC-related class Ib molecules which are expressed on antigen-presenting cells. Vδ2 T cells recognize phosphoantigens via forming tight complexes following binding with BTN3A1, and in the context of costimulators, Vδ2 T cells are activated and expanded. Vδ3 T cells can be activated by CD1d which may combine with glycolipid and kill CD1d target cells. Activated Vδ2 T cells and Vδ1 T cells could activate the expression of Toll-like receptors which have the capacity to recognize infectious pathogen-associated molecule patterns. Activation and proliferation of γδ T cells exert their potential effector functions via producing cytokines, chemokines, and lytic enzymes, performing cytotoxic and noncytolytic antiviral activities, presenting antigens to CD4⁺ and CD8⁺ T cells, inducing maturation of dendritic cells (DCs), providing B cell help, and so on.