title: Sensitivity of IFN-gamma release assay to detect latent tuberculosis infection is retained in HIV-infected patients but dependent on HIV/AIDS progression.
abstract: BACKGROUND
  Detection and treatment of latent TB infection (LTBI) in HIV infected individuals is strongly recommended to decrease morbidity and mortality in countries with high levels of HIV.
  
  
  OBJECTIVE
  To assess the validity of a newly developed in-house ELISPOT interferon-gamma release assay (IGRA) for the detection of LTBI amongst HIV infected individuals, in comparison with the Tuberculin Skin Test (TST).
  
  
  RESULTS
  ESAT6/CFP10 (EC) ELISPOT assays were performed, together with a TST, in 285 HIV infected individuals recruited in HIV clinics in Dakar, Senegal, who had no signs of active TB at time of enrolment. Thirty eight of the subjects (13.3%) failed to respond to PHA stimulation and were excluded from the analysis. In the 247 remaining patients, response to PHA did not vary according to CD4 cell count categories (p = 0.51). EC ELISPOT was positive in 125 (50.6%) subjects, while 53 (21.5%) had a positive TST. Concordance between EC ELISPOT and TST was observed in 151 patients (61.1%) (kappa = 0.23). The proportion of subjects with a positive response to the EC ELISPOT assay decreased with declining CD4 counts (p trend = 0.001), but were consistently higher than the proportion of TST responders. In multivariate analysis, the risk of being EC-ELISPOT positive in HIV infected individuals was associated with age, CD4 count and HIV-1 strain.
  
  
  CONCLUSIONS
  Our study indicates that IGRAs using M. tuberculosis specific antigens are likely to retain their validity for the diagnosis of LTBI among HIV positive individuals, but may be impaired by T-cell anergy in severely immuno-suppressed individuals.
authors.affiliation: Laboratoire de Bactériologie - Virologie, Hôpital Aristide Le Dantec, Dakar, Senegal.
authors.forename: Farba
authors.initials: F
authors.lastname: Karam
authors.forename: Fatou
authors.initials: F
authors.lastname: Mbow
authors.forename: Helen
authors.initials: H
authors.lastname: Fletcher
authors.forename: Cheikh S
authors.initials: CS
authors.lastname: Senghor
authors.forename: Koura D
authors.initials: KD
authors.lastname: Coulibaly
authors.forename: Andrea M
authors.initials: AM
authors.lastname: LeFevre
authors.forename: Ndeye F
authors.initials: NF
authors.lastname: Ngom Gueye
authors.forename: Tandakha
authors.initials: T
authors.lastname: Dieye
authors.forename: Papa S
authors.initials: PS
authors.lastname: Sow
authors.forename: Souleymane
authors.initials: S
authors.lastname: Mboup
authors.forename: Christian
authors.initials: C
authors.lastname: Lienhardt
mesh_terms: D017088:AIDS-Related Opportunistic Infections / Q000150:complications / Q000175:diagnosis* / Q000473:pathology; D018450:Disease Progression; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism*; D012680:Sensitivity and Specificity; D014376:Tuberculosis / Q000150:complications / Q000175:diagnosis* / Q000473:pathology
chemical_list: D007371:Interferon-gamma