Human γδ T Cells Augment Antigen Presentation in Listeria Monocytogenes Infection

Circulating gamma delta T cells in healthy individuals rapidly respond to bacterial and viral pathogens. Many studies have demonstrated that gamma delta T cells are activated and expanded by Listeria monocytogenes (L. monocytogenes), a foodborne bacterial pathogen with high fatality rates. However, the roles of gamma delta T cells during L. monocytogenes infection are not clear. In the present study, we characterized the morphological characteristics of phagocytosis in gamma delta 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 gamma delta T cells were upregulated after stimulation via L. monocytogenes. Significant proliferation and differentiation of primary alpha beta T cells was also observed after coculture of peripheral blood mononuclear cells with gamma delta T cells anteriorly stimulated by L. monocytogenes. L. monocytogenes infection decreased the percentage of gamma delta T cells in mouse -intraepithelial lymphocytes (IELs) and increased MHC-II expression on the surface of gamma delta T cells in vivo. Our findings shed light on antigen presentation of gamma delta T cells during L. monocytogenes infection.