title: Distinct patterns of HIV-specific memory T lymphocytes in HIV-exposed uninfected individuals and in HIV-infected patients.
abstract: BACKGROUND
  Repeated exposure to HIV is not always associated with infection and multiple cohorts of HIV-exposed but seronegative individuals (ESN) have been described. HIV-specific CD4 and CD8 T lymphocytes are detected both in HIV patients and in ESN; we verified whether different patterns of HIV-specific memory T lymphocytes would be detected in individuals in whom exposure to HIV results or does not result in infection.
  
  
  METHODS
  Gag-specific T cells were analysed in 15 ESN, 14 HIV patients, and 15 healthy controls using extensive flow cytometry analysis.
  
  
  RESULTS
  Data confirmed that gag-specific T lymphocytes are present in ESN. Gag-specific T cells mainly secrete interleukin-2 in ESN and interferon-gamma in HIV patients. In addition the CD4/CD8 and the memory/naive ratios are altered, central memory (45RA-/CCR7+) CD4 and CD8 T lymphocytes are more abundant, and terminally differentiated (45RA+/CCR7- and 27-/28-) CD8 T lymphocytes are augmented in ESN individuals.
  
  
  CONCLUSIONS
  Exposure to HIV occurs in high risk seronegative individuals; the observation that naive cells and CM are skewed in ESN indicate that this exposure is robust enough to modulate the CM/EM ratio. The increase in late effectors and in natural killer cells seen in ESN suggests a role for these cells in preventing actual infection.
authors.affiliation: Immunology DISP LITA Vialba, University of Milano, Milano, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Schenal
authors.forename: Sergio
authors.initials: S
authors.lastname: Lo Caputo
authors.forename: Francesca
authors.initials: F
authors.lastname: Fasano
authors.forename: Francesca
authors.initials: F
authors.lastname: Vichi
authors.forename: Marina
authors.initials: M
authors.lastname: Saresella
authors.forename: Piera
authors.initials: P
authors.lastname: Pierotti
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Villa
authors.forename: Francesco
authors.initials: F
authors.lastname: Mazzotta
authors.forename: Daria
authors.initials: D
authors.lastname: Trabattoni
authors.forename: Mario
authors.initials: M
authors.lastname: Clerici
mesh_terms: D000328:Adult; D016516:CD4-CD8 Ratio; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D016022:Case-Control Studies; D005260:Female; D005434:Flow Cytometry; D006678:HIV; D016655:HIV Core Protein p24 / Q000032:analysis; D018023:HIV Seronegativity / Q000276:immunology*; D006679:HIV Seropositivity / Q000276:immunology*; D006801:Humans; D007156:Immunologic Memory; D007371:Interferon-gamma / Q000378:metabolism; D007376:Interleukin-2 / Q000378:metabolism; D018655:Lymphocyte Count; D008297:Male; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D016655:HIV Core Protein p24; D007376:Interleukin-2; D007371:Interferon-gamma