title: Antigen-stimulated apoptotic T-cell death in HIV infection is selective for CD4+ T cells, modulated by cytokines and effected by lymphotoxin.
abstract: OBJECTIVE
  To characterize the mechanism of in vitro antigen-induced apoptotic T-cell death in the peripheral blood mononuclear cells (PBMC) of HIV-1-infected individuals.
  
  
  METHODS
  PBMC from HIV-1 infected and uninfected individuals were unstimulated or stimulated with HIV-1 envelope synthetic peptides (Env) or influenza A virus to determine the extent of antigen-stimulated apoptotic T-cell death, whether this death was limited to the CD4+ subset, and the effects of cytokines on T-cell death. Death was assessed by apoptotic nuclear morphology after 7 days of culture by fluorescence microscopy using a DNA-specific dye. Transwell cultures and supernatant transfers were utilized to test whether a soluble factor produced by HIV-positive PBMC induced death of HIV-negative T cells. Exogenous cytokines [interleukin (IL)-12, interferon (IFN)-gamma, IL-4 and IL-10], as well as antibodies against endogenously produced cytokines (IL-4, IL-10, IL-12, and lymphotoxin) were tested for their ability to modulate death.
  
  
  RESULTS
  Antigenic stimulation induced death in PBMC from HIV-positive donors, but not in PBMC from HIV-negative donors. Antigen-stimulated death was seen in CD4+ but not CD8+ T-cell subset from the HIV-positive patients. Apoptotic death was blocked by IL-12, IFN-gamma, anti-IL-4, anti-IL-10, and anti-lymphotoxin, but not by anti-IL-12. Transwell and supernatant transfer experiment indicated that antigen-stimulated HIV-positive PBMC produced a factor that killed T-cell blasts. The factor was inhibited by anti-lymphotoxin, but not by anti-IL-10.
  
  
  CONCLUSIONS
  Stimulation of HIV-positive PBMC with CD4-dependent antigens results in selective death of CD4+ T cells that is modulated by cytokines. Our results suggest that apoptotic death is not limited to HIV-infected or HIV-specific T cells, but occurs in bystander cells. Lymphotoxin is a mediator of antigen-stimulated T-cell death in this in vitro model.
authors.affiliation: Cattedra di Immunologia, Universitá degli Studi di Milano, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Clerici
authors.forename: A
authors.initials: A
authors.lastname: Sarin
authors.forename: J A
authors.initials: JA
authors.lastname: Berzofsky
authors.forename: A L
authors.initials: AL
authors.lastname: Landay
authors.forename: H A
authors.initials: HA
authors.lastname: Kessler
authors.forename: F
authors.initials: F
authors.lastname: Hashemi
authors.forename: C W
authors.initials: CW
authors.lastname: Hendrix
authors.forename: S P
authors.initials: SP
authors.lastname: Blatt
authors.forename: J
authors.initials: J
authors.lastname: Rusnak
authors.forename: M J
authors.initials: MJ
authors.lastname: Dolan
authors.forename: R L
authors.initials: RL
authors.lastname: Coffman
authors.forename: P A
authors.initials: PA
authors.lastname: Henkart
authors.forename: G M
authors.initials: GM
authors.lastname: Shearer
mesh_terms: D000906:Antibodies / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000473:pathology*; D002478:Cells, Cultured; D016207:Cytokines / Q000276:immunology; D015488:HIV Antigens / Q000276:immunology*; D015658:HIV Infections / Q000276:immunology* / Q000473:pathology; D006801:Humans; D008233:Lymphotoxin-alpha / Q000276:immunology
chemical_list: D000906:Antibodies; D016207:Cytokines; D015488:HIV Antigens; D008233:Lymphotoxin-alpha