title: Hepatitis C virus (HCV)-specific T-cell responses among recombinant immunoblot assay-3-indeterminate blood donors: a confirmatory evidence of HCV exposure.
abstract: BACKGROUND
  Blood donors are routinely screened for hepatitis C virus (HCV) infection. Some show weak anti-HCV responses, often restricted to a single antigen on confirmatory immunoblot (recombinant immunoblot assay [RIBA]) testing. The aim of this study was to investigate the extent to which such RIBA-indeterminate donors had previously been exposed to HCV.
  
  
  METHODS
  T-cell responses to HCV recombinant proteins (core, NS3, and NS3 helicase) were analyzed using an interferon-gamma (IFN-gamma) enzyme-linked immunospot (ELISpot) assay and quantification of cytokines in culture supernatants in 27 RIBA-indeterminate donors, 60 RIBA-confirmed donors (48 with and 12 without HCV RNA), and 30 RIBA-negative donors.
  
  
  RESULTS
  HCV-specific T-cell responses were identified in 13 (48%) RIBA-indeterminate donors, 33 (55%) RIBA-confirmed donors, and 4 (13%) RIBA-negative controls (p = 0.008 and p < 0.001, respectively). The magnitude of the T-cell response among indeterminate donors was similar to that of RIBA-confirmed donors for all HCV antigens and the specificity of the ELISpot results was confirmed by antigen-specific cytokine production (interleukin-2 and IFN-gamma) in short-term culture supernatants.
  
  
  CONCLUSIONS
  These findings confirm that approximately half of RIBA-indeterminate donors have resolved a previous HCV infection and suggest that ELISpot might be a useful tool to clarify the status of such donors and help in their counseling and management.
authors.affiliation: Transfusion Safety Laboratory, Banc de Sang i Teixits de Catalunya, Passeig Vall d'Hebron 119-129, Barcelona, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Bes
authors.forename: Juan Ignacio
authors.initials: JI
authors.lastname: Esteban
authors.forename: Natàlia
authors.initials: N
authors.lastname: Casamitjana
authors.forename: Maria
authors.initials: M
authors.lastname: Piron
authors.forename: Josep
authors.initials: J
authors.lastname: Quer
authors.forename: María
authors.initials: M
authors.lastname: Cubero
authors.forename: Lluís
authors.initials: L
authors.lastname: Puig
authors.forename: Jaime
authors.initials: J
authors.lastname: Guardia
authors.forename: Sílvia
authors.initials: S
authors.lastname: Sauleda
mesh_terms: D001782:Blood Donors; D005838:Genotype; D016174:Hepacivirus / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D006526:Hepatitis C / Q000175:diagnosis* / Q000235:genetics / Q000276:immunology*; D018936:Hepatitis C Antigens / Q000276:immunology*; D006801:Humans; D007111:Immunity, Cellular; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012703:Serotyping; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D018936:Hepatitis C Antigens