title: Potential role of M. tuberculosis specific IFN-γ and IL-2 ELISPOT assays in discriminating children with active or latent tuberculosis.
abstract: BACKGROUND
  Although currently available IGRA have been reported to be promising markers for TB infection, they cannot distinguish active tuberculosis (TB) from latent infection (LTBI).
  
  
  OBJECTIVE
  Children with LTBI, active TB disease or uninfected were prospectively evaluated by an in-house ELISPOT assay in order to investigate possible immunological markers for a differential diagnosis between LTBI and active TB.
  
  
  METHODS
  Children at risk for TB infection prospectively enrolled in our infectious disease unit were evaluated by in-house IFN-γ and IL-2 based ELISPOT assays using a panel of Mycobacterium tuberculosis antigens.
  
  
  RESULTS
  Twenty-nine children were classified as uninfected, 21 as LTBI and 25 as active TB cases (including 5 definite and 20 probable cases). Significantly higher IFN-γ ELISPOT responses were observed in infected vs. uninfected children for ESAT-6 (p<0.0001), CFP-10 (p<0.0001), TB 10.3 (p = 0.003), and AlaDH (p = 0.001), while differences were not significant considering Ag85B (p = 0.063), PstS1 (p = 0.512), and HspX (16 kDa) (p = 0.139). IL-2 ELISPOT assay responses were different for ESAT-6 (p<0.0001), CFP-10 (p<0.0001), TB 10.3 (p<0.0001), HspX (16 kDa) (p<0.0001), PstS1 (p<0.0001) and AlaDH (p = 0.001); but not for Ag85B (p = 0.063). Comparing results between children with LTBI and those with TB disease differences were significant for IFN-γ ELISPOT only for AlaDH antigen (p = 0.021) and for IL-2 ELISPOT assay for AlaDH (p<0.0001) and TB 10.3 antigen (p = 0.043). ROC analyses demonstrated sensitivity of 100% and specificity of 81% of AlaDH-IL-2 ELISPOT assay in discriminating between latent and active TB using a cut off of 12.5 SCF per million PBMCs.
  
  
  CONCLUSIONS
  Our data suggest that IL-2 based ELISPOT with AlaDH antigen may be of help in discriminating children with active from those with latent TB.
authors.affiliation: Anna Meyer University Hospital, Department of Science for Woman and Child Health, University of Florence, Italy. echiappini@unifi.it
authors.forename: Elena
authors.initials: E
authors.lastname: Chiappini
authors.forename: Chiara
authors.initials: C
authors.lastname: Della Bella
authors.forename: Francesca
authors.initials: F
authors.lastname: Bonsignori
authors.forename: Sara
authors.initials: S
authors.lastname: Sollai
authors.forename: Amedeo
authors.initials: A
authors.lastname: Amedei
authors.forename: Luisa
authors.initials: L
authors.lastname: Galli
authors.forename: Elena
authors.initials: E
authors.lastname: Niccolai
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Del Prete
authors.forename: Mahavir
authors.initials: M
authors.lastname: Singh
authors.forename: Mario M
authors.initials: MM
authors.lastname: D'Elios
authors.forename: Maurizio
authors.initials: M
authors.lastname: de Martino
mesh_terms: D000942:Antigens, Bacterial / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D058501:Enzyme-Linked Immunospot Assay / Q000379:methods*; D006801:Humans; D007223:Infant; D007371:Interferon-gamma / Q000276:immunology; D007376:Interleukin-2 / Q000276:immunology; D055985:Latent Tuberculosis / Q000175:diagnosis* / Q000276:immunology; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D011446:Prospective Studies; D014376:Tuberculosis / Q000175:diagnosis* / Q000276:immunology
chemical_list: D000942:Antigens, Bacterial; D007376:Interleukin-2; C072681:Mycobacterium tuberculosis antigens; D007371:Interferon-gamma