title: Double-negative T cells during HIV/SIV infections:  potential pinch hitters in the T-cell lineup.
abstract: OBJECTIVE
  This review summarizes the role of CD3+CD4-CD8- double-negative T cells, which have both regulatory and helper T-cell functions and may have the potential to compensate for the reduced levels of CD4 T cells during SIV/HIV infection.
  
  
  RESULTS
  Double-negative T cells have been characterized in several human diseases and in murine models of autoimmunity and transplantation, where they exhibit both immunoregulatory and helper T-cell-like function. During the natural nonpathogenic SIV infection of African nonhuman primates, the lack of clinical disease progression is associated with the presence of double-negative T cells that maintain helper T-cell functions while remaining refractory to viral infection. Moreover, DN T cells may compensate for very low levels of CD4+ T cells observed in a cohort of SIV-infected sooty mangabeys that have remained free of clinical AIDS for over 10 years. These studies identify a potential for double-negative T cells to provide critical helper function during HIV infection.
  
  
  CONCLUSIONS
  Double-negative T cells with some CD4+ T-cell functions are associated with a nonpathogenic outcome during SIV infection and represent a potential immune therapeutic target in HIV-infected patients.
authors.affiliation: Seattle Biomedical Research Institute, Seattle, Washington, USA.
authors.forename: Vasudha
authors.initials: V
authors.lastname: Sundaravaradan
authors.forename: Kiran D
authors.initials: KD
authors.lastname: Mir
authors.forename: Donald L
authors.initials: DL
authors.lastname: Sodora
mesh_terms: D000818:Animals; D017252:CD3 Complex / Q000378:metabolism*; D016665:Cercocebus atys / Q000821:virology; D015331:Cohort Studies; D018450:Disease Progression; D015658:HIV Infections / Q000276:immunology* / Q000503:physiopathology / Q000821:virology; D015497:HIV-1 / Q000276:immunology; D006801:Humans; D008253:Macaca mulatta; D008992:Monkey Diseases / Q000276:immunology / Q000503:physiopathology / Q000821:virology; D016097:Simian Acquired Immunodeficiency Syndrome / Q000276:immunology* / Q000503:physiopathology / Q000821:virology; D015302:Simian Immunodeficiency Virus / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
chemical_list: D017252:CD3 Complex