title: CD8+ cells from HIV-2-infected baboons control HIV replication.
abstract: OBJECTIVE
  To analyze the CD8+ cell antiviral immune response in HIV-2-infected baboons.
  
  
  METHODS
  Baboons were infected with clinical isolates of HIV-2, CD8+ cells were isolated from phytohemagglutinin (PHA)-stimulated baboon peripheral blood mononuclear cells (PBMC). These cells were cultured with PHA-stimulated CD4+ cells acutely infected with HIV-2 at several CD8+:CD4+ cell ratios. Control of HIV-2 replication was determined by comparing peak levels of HIV-2 replication in fluids from CD8+:CD4+ cell cocultures with those in fluids from infected CD4+ cells cultured alone.
  
  
  RESULTS
  CD8+ cells from HIV-2-infected baboons inhibited HIV-2 replication in acutely infected autologous CD4+ cells to a significantly greater extent than did CD8+ cells from uninfected baboons (P = 0.0001). At the beginning of the acute phase of HIV-2 infection, CD8+ cells showed either a transient reduction or loss in the antiviral activity. In some cases the CD8+ cell response enhanced HIV-2 replication. Subsequently, the strength of the CD8+ cell antiviral activity increased concomitant with a decrease in the HIV-2 load in the PBMC. Suppression of HIV replication could be demonstrated with filtered fluid from CD8+ cells. Other studies indicated that infected CD4+ cells are lost during coculture of CD8+ cells with infected CD4+ cells.
  
  
  CONCLUSIONS
  CD8+ cells of HIV-2-infected baboons develop substantial anti-HIV-2 activity following HIV-2 infection, which may account in part for the low frequency of pathogenesis in HIV-2-infected baboons. Studies to elucidate the mechanism of this CD8+ cell antiviral activity suggest that it is mediated in part by a soluble antiviral factor, but primarily in association with the loss of infected CD4+ cells.
authors.affiliation: Department of Medicine, University of California, San Francisco 94143, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Blackbourn
authors.forename: C P
authors.initials: CP
authors.lastname: Locher
authors.forename: B
authors.initials: B
authors.lastname: Ramachandran
authors.forename: S W
authors.initials: SW
authors.lastname: Barnett
authors.forename: K K
authors.initials: KK
authors.lastname: Murthy
authors.forename: K D
authors.initials: KD
authors.lastname: Carey
authors.forename: K M
authors.initials: KM
authors.lastname: Brasky
authors.forename: J A
authors.initials: JA
authors.lastname: Levy
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000821:virology; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000821:virology; D002478:Cells, Cultured; D018920:Coculture Techniques; D015658:HIV Infections / Q000097:blood / Q000821:virology; D015498:HIV-2 / Q000276:immunology* / Q000502:physiology; D006801:Humans; D008221:Lymphoid Tissue / Q000166:cytology; D010215:Papio; D014779:Virus Replication