title: IP-10 is an additional marker for tuberculosis (TB) detection in HIV-infected persons in a low-TB endemic country.
abstract: OBJECTIVE
  In Indian HIV-infected patients, IP-10 response to QuantiFERON-TB Gold In tube (QFT-IT) antigens has been associated to tuberculosis (TB). However, specificity for active TB was lower than that reported by QFT-IT, making accuracy for TB detection questionable. To investigate this uncertainty, likely due to India being highly endemic for TB, and to better identify TB correlates, we evaluated the IP-10-based assay in HIV-infected subjects in Italy, a low-TB endemic country.
  
  
  METHODS
  195 individuals were prospectively enrolled; 118 were HIV-infected (21 with active TB, 97 without active TB, and distinguished as high/low-TB-risk). QFT-IT was performed and IP-10 was evaluated by ELISA.
  
  
  RESULTS
  Among the HIV-infected individuals, sensitivity for active TB was 66.7% by IP-10-based test and 52.4% (p = 1) by QFT-IT. IP-10-based assay showed a lower dependence on mitogen-response and CD4 counts than QFT-IT. Among subjects without active TB, a higher proportion of IP-10 responders was shown in high-TB-risk subjects than low-TB-risk subjects (40.0% vs 12.9%), similar to QFT-IT (37.1% vs 4.8%). Low-TB risk subjects showed 87.1% specificity for active TB by IP-10-based test vs 95.2% by QFT-IT.
  
  
  CONCLUSIONS
  In a low-TB endemic country, besides IFN-γ, IP-10 response to QFT-IT is associated with active TB and TB risk factors in HIV-infected patients with lower dependence on mitogen-response and CD4 counts.
authors.affiliation: Translational Research Unit, Department of Epidemiology and Preclinical Research, L. Spallanzani National Institute for Infectious Diseases (INMI), IRCCS, Via Portuense 292, 00149 Rome, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Vanini
authors.forename: Elisa
authors.initials: E
authors.lastname: Petruccioli
authors.forename: Cristiana
authors.initials: C
authors.lastname: Gioia
authors.forename: Gilda
authors.initials: G
authors.lastname: Cuzzi
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Orchi
authors.forename: Alessia
authors.initials: A
authors.lastname: Rianda
authors.forename: Lucia
authors.initials: L
authors.lastname: Alba
authors.forename: Maria Letizia
authors.initials: ML
authors.lastname: Giancola
authors.forename: Aristide
authors.initials: A
authors.lastname: Conte
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Schininà
authors.forename: Elisa Busi
authors.initials: EB
authors.lastname: Rizzi
authors.forename: Enrico
authors.initials: E
authors.lastname: Girardi
authors.forename: Delia
authors.initials: D
authors.lastname: Goletti
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood*; D054357:Chemokine CXCL10 / Q000097:blood*; D019411:Clinical Laboratory Techniques / Q000379:methods; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D015658:HIV Infections / Q000150:complications*; D006801:Humans; D059425:Interferon-gamma Release Tests / Q000379:methods; D007558:Italy; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D014376:Tuberculosis / Q000175:diagnosis*
chemical_list: D015415:Biomarkers; C114753:CXCL10 protein, human; D054357:Chemokine CXCL10