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 human leucocyte antigen DR (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 coculture 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 intraepithelial lymphocytes (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.