title: Intestinal double-positive CD4+CD8+ T cells are highly activated memory cells with an increased capacity to produce cytokines.
abstract: Peripheral blood and intestinal CD4+CD8+ double-positive (DP) T cells have been described in several species including humans, but their function and immunophenotypic characteristics are still not clearly understood. Here we demonstrate that DP T cells are abundant in the intestinal lamina propria of normal rhesus macaques (Macaca mulatta). Moreover, DP T cells have a memory phenotype and are capable of producing different and/or higher levels of cytokines and chemokines in response to mitogen stimulation compared to CD4+ single-positive T cells. Intestinal DP T cells are also highly activated and have higher expression of CCR5, which makes them preferred targets for simian immunodeficiency virus/HIV infection. Increased levels of CD69, CD25 and HLA-DR, and lower CD62L expression were found on intestinal DP T cells populations compared to CD4+ single-positive T cells. Collectively, these findings demonstrate that intestinal and peripheral blood DP T cells are effector cells and may be important in regulating immune responses, which distinguishes them from the immature DP cells found in the thymus. Finally, these intestinal DP T cells may be important target cells for HIV infection and replication due to their activation, memory phenotype and high expression of CCR5.
authors.affiliation: Tulane National Primate Research Center, Tulane University School of Medicine, Covington, LA 70433, USA. bpahar@tulane.edu
authors.forename: Bapi
authors.initials: B
authors.lastname: Pahar
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Lackner
authors.forename: Ronald S
authors.initials: RS
authors.lastname: Veazey
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D016207:Cytokines / Q000276:immunology* / Q000378:metabolism; D006678:HIV / Q000276:immunology; D015658:HIV Infections / Q000276:immunology; D006684:HLA-DR Antigens / Q000276:immunology; D018928:Immunity, Mucosal / Q000276:immunology*; D007156:Immunologic Memory / Q000276:immunology*; D007422:Intestines / Q000166:cytology / Q000276:immunology*; D008213:Lymphocyte Activation; D008253:Macaca mulatta; D009092:Mucous Membrane / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D009928:Organ Specificity / Q000276:immunology; D019713:Receptors, CCR5 / Q000276:immunology; D015302:Simian Immunodeficiency Virus / Q000276:immunology; D014779:Virus Replication / Q000276:immunology
chemical_list: D015703:Antigens, CD; D016207:Cytokines; D006684:HLA-DR Antigens; D019713:Receptors, CCR5