title: PD-1 expression on human CD8 T cells depends on both state of differentiation and activation status.
abstract: OBJECTIVE
  PD-1 expression on HIV-specific CD8 T cells was recently reported to reflect functional exhaustion, resulting in uncontrolled HIV-1 replication. Assessing PD-1 expression on T cells may be highly relevant in T-cell immunology and vaccine monitoring. However, this requires us to gain further insights into the significance of PD-1 expression on CD8 T cells in humans.
  
  
  METHODS
  We performed a detailed analysis of PD-1 expression pattern on various CD8 T cell subsets from healthy or HIV infected donors.
  
  
  RESULTS
  PD-1 expression has two facets in vivo. On the one hand, it is linked to T-cell differentiation: PD-1 is up-regulated on early/intermediate differentiated subsets, which include HIV and Epstein-Barr virus-specific CD8 T-cell populations, but is down-regulated during late stages of differentiation. On the other hand, it is linked to T-cell activation: on PD-1 positive cells, PD-1 over-expression occurs along with the up-regulation of activation markers such as CD38 or HLA-DR.
  
  
  CONCLUSIONS
  PD-1 expression on CD8 T cells, including those specific for HIV, can be related both to their differentiation stage and their activation status. It is important to consider these findings when assessing the expression of PD-1 on T cells.
authors: Cellular Immunology laboratory, INSERM U543, Avenir Group, Hôpital Pitié-Salpêtrière, Université Pierre et Marie Curie-Paris 6, Paris, France.
authors: Delphine
authors: D
authors: Sauce
authors: Jorge R
authors: JR
authors: Almeida
authors: Martin
authors: M
authors: Larsen
authors: Laurine
authors: L
authors: Haro
authors: Brigitte
authors: B
authors: Autran
authors: Gordon J
authors: GJ
authors: Freeman
authors: Victor
authors: V
authors: Appay
mesh_terms: D051997:ADP-ribosyl Cyclase 1 / Q000096:biosynthesis; D015703:Antigens, CD / Q000378:metabolism*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D018414:CD8-Positive T-Lymphocytes / Q000378:metabolism*; D016022:Case-Control Studies; D002454:Cell Differentiation; D015658:HIV Infections / Q000378:metabolism*; D004854:Herpesvirus 4, Human / Q000378:metabolism; D006801:Humans; D008213:Lymphocyte Activation; D061026:Programmed Cell Death 1 Receptor
chemical_list: D015703:Antigens, CD; D051017:Apoptosis Regulatory Proteins; C105992:PDCD1 protein, human; D061026:Programmed Cell Death 1 Receptor; D051997:ADP-ribosyl Cyclase 1