Sensitivity of IFN-gamma release assay to detect latent tuberculosis infection is retained in HIV-infected patients but dependent on HIV/AIDS progression.
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.
Karam
Farba
F
Laboratoire de Bactériologie - Virologie, Hôpital Aristide Le Dantec, Dakar, Senegal.
Mbow
Fatou
F
Fletcher
Helen
H
Senghor
Cheikh S
CS
Coulibaly
Koura D
KD
LeFevre
Andrea M
AM
Ngom Gueye
Ndeye F
NF
Dieye
Tandakha
T
Sow
Papa S
PS
Mboup
Souleymane
S
Lienhardt
Christian
C
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
D007371:Interferon-gamma