title: T-cell and serological responses to Erp, an exported Mycobacterium tuberculosis protein, in tuberculosis patients and healthy individuals.
abstract: BACKGROUND
  The identification of antigens able to differentiate tuberculosis (TB) disease from TB infection would be valuable. Cellular and humoral immune responses to Erp (Exported repetitive protein)--a recently identified M. tuberculosis protein--have not yet been investigated in humans and may contribute to this aim.
  
  
  METHODS
  We analyzed the cellular and humoral immune responses to Erp, ESAT-6, Ag85B and PPD in TB patients, in BCG+ individuals without infection, BCG+ individuals with latent TB infection (LTBI) and BCG- controls. We used lymphoproliferation, ELISpot IFN-gamma, cytokine production assays and detection of specific human antibodies against recombinant M. tuberculosis proteins.
  
  
  RESULTS
  We included 22 TB patients, 9 BCG+ individuals without TB infection, 7 LTBI and 7 BCG- controls. Erp-specific T cell counts were higher in LTBI than in the other groups. Erp-specific T cell counts were higher in LTBI subjects than TB patients (median positive frequency of 211 SFC/106 PBMC (range 118-2000) for LTBI subjects compared to 80 SFC/106 PBMC (range 50-191), p = 0.019); responses to PPD and ESAT-6 antigens did not differ between these groups. IFN-gamma secretion after Erp stimulation differed between TB patients and LTBI subjects (p = 0.02). Moreover, LTBI subjects but not TB patients or healthy subjects produced IgG3 against Erp.
  
  
  CONCLUSIONS
  The frequencies of IFN-gamma-producing specific T cells, the IFN-gamma secretion and the production of IgG3 after Erp stimulation are higher in LTBI subjects than in TB patients, whereas PPD and ESAT-6 are not.
authors.affiliation: Laboratoire d'Immunologie Cellulaire, INSERM U543, Hôpital Pitié-Salpêtrière, Paris Cedex 13, France. valerie.martinez@psl.aphp.fr
authors.forename: Valérie
authors.initials: V
authors.lastname: Martinez
authors.forename: Guislaine
authors.initials: G
authors.lastname: Carcelain
authors.forename: Edgar
authors.initials: E
authors.lastname: Badell
authors.forename: Marc
authors.initials: M
authors.lastname: Jouan
authors.forename: Isabelle
authors.initials: I
authors.lastname: Mauger
authors.forename: Pierre
authors.initials: P
authors.lastname: Sellier
authors.forename: Chantal
authors.initials: C
authors.lastname: Truffot
authors.forename: François
authors.initials: F
authors.lastname: Bricaire
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Arend
authors.forename: Tom
authors.initials: T
authors.lastname: Ottenhoff
authors.forename: Brigitte
authors.initials: B
authors.lastname: Autran
authors.forename: Brigitte
authors.initials: B
authors.lastname: Gicquel
mesh_terms: D000328:Adult; D000368:Aged; D001426:Bacterial Proteins / Q000276:immunology*; D015415:Biomarkers; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007111:Immunity, Cellular / Q000276:immunology; D007074:Immunoglobulin G / Q000378:metabolism; D007371:Interferon-gamma / Q000276:immunology / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000276:immunology*; D008875:Middle Aged; D009163:Mycobacterium bovis / Q000276:immunology; D009169:Mycobacterium tuberculosis / Q000276:immunology* / Q000378:metabolism; D011446:Prospective Studies; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D014376:Tuberculosis / Q000175:diagnosis* / Q000276:immunology*
chemical_list: D001426:Bacterial Proteins; D015415:Biomarkers; C096737:ERP protein, Mycobacterium tuberculosis; D007074:Immunoglobulin G; D008565:Membrane Proteins; D007371:Interferon-gamma