Human γδ T cells augment antigen presentation in Listeria Monocytogenes infection

Circulating γδ T cells in healthy individuals rapidly respond to bacterial and viral pathogens. Many studies have demonstrated that γδ T cells are activated and expanded by Listeria monocytogenes (L.monocytogenes), a foodborne bacterial pathogen with high fatality rates. However, the roles of γδ T cells during L.monocytogenes infection are not clear. In the present study, we characterized the morphological characteristics of phagocytosis in γδ T cells after L.monocytogenes infection using transmission electron microscopy. Results show activation markers including HLA-DR and lymph node-homing receptor CCR7 on γδ T cells were upregulated after stimulation via L.monocytogenes. Significant proliferation and differentiation of primary αβ T cells was also observed after co-culture of peripheral blood mononuclear cells with γδ T cells anteriorly stimulated by L.monocytogenes. L.monocytogenes infection decreased the percentage of γδ T cells in mouse IELs and increased MHC-II expression on the surface of γδ T cells in vivo. Our findings shed light on antigen presentation of γδ T cells during L.monocytogenes infection.