title: Platelet activation suppresses HIV-1 infection of T cells.
abstract: BACKGROUND
  Platelets, anucleate cell fragments abundant in human blood, can capture HIV-1 and platelet counts have been associated with viral load and disease progression. However, the impact of platelets on HIV-1 infection of T cells is unclear.
  
  
  RESULTS
  We found that platelets suppress HIV-1 spread in co-cultured T cells in a concentration-dependent manner. Platelets containing granules inhibited HIV-1 spread in T cells more efficiently than degranulated platelets, indicating that the granule content might exert antiviral activity. Indeed, supernatants from activated and thus degranulated platelets suppressed HIV-1 infection. Infection was inhibited at the stage of host cell entry and inhibition was independent of the viral strain or coreceptor tropism. In contrast, blockade of HIV-2 and SIV entry was less efficient. The chemokine CXCL4, a major component of platelet granules, blocked HIV-1 entry and neutralization of CXCL4 in platelet supernatants largely abrogated their anti-HIV-1 activity.
  
  
  CONCLUSIONS
  Release of CXCL4 by activated platelets inhibits HIV-1 infection of adjacent T cells at the stage of virus entry. The inhibitory activity of platelet-derived CXCL4 suggests a role of platelets in the defense against infection by HIV-1 and potentially other pathogens.
authors: Institute of Virology, Hannover Medical School, Hannover, Germany.
authors: Theodros
authors: T
authors: Solomon Tsegaye
authors: Kerstin
authors: K
authors: Gnirß
authors: Niels
authors: N
authors: Rahe-Meyer
authors: Miriam
authors: M
authors: Kiene
authors: Annika
authors: A
authors: Krämer-Kühl
authors: Georg
authors: G
authors: Behrens
authors: Jan
authors: J
authors: Münch
authors: Stefan
authors: S
authors: Pöhlmann
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000821:virology*; D002478:Cells, Cultured; D015497:HIV-1 / Q000276:immunology* / Q000502:physiology*; D006801:Humans; D015539:Platelet Activation; D010978:Platelet Factor 4 / Q000276:immunology*; D053586:Virus Internalization / Q000187:drug effects*
chemical_list: D010978:Platelet Factor 4
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