Longitudinal observation of an interferon gamma-released assay (T-SPOT.TB) for Mycobacterium tuberculosis infection in AIDS patients on highly active antiretroviral therapy.
BACKGROUND
T-SPOT.TB is a novel test for tuberculosis infection with higher sensitivity and specificity than the traditional tuberculin skin test (TST). However, there are no longitudinal data in the literature evaluating T-SPOT.TB for Mycobacterium tuberculosis in patients with acquired immune deficiency syndrome (AIDS) on highly active antiretroviral therapy (HAART). The objective of this study was to assess the value of T-SPOT.TB longitudinally in AIDS patients on HAART without prophylaxis for tuberculosis.


METHODS
A prospective observational study was conducted in 50 AIDS patients on HAART. None of the subjects had evidence of active tuberculosis. T-SPOT.TB, a T-cell-based interferon gamma released assay, was performed at the onset of the study and repeated 24 months thereafter. Subjects were evaluated every 6 months during the 36-month follow-up.


RESULTS
Twenty-one (42%) AIDS patients on HAART tested positive by T-SPOT.TB (95%CI 28.3% - 55.7%). The pooled spot-forming cells of early secretory antigenic target-6 (ESAT-6) and culture filtrate protein-10 (CFP-10) peptides were 68/million peripheral blood mononuclear cell (PBMC) (interquartile range 44 - 220). The average number of CD4 cells in subjects was (305 +/- 152) cells/microl, and there was no significant difference in T-SPOT.TB response rates between subjects with CD4 cell counts < 200 cells/microl (7/15 (46.7%), 95%CI 21.5% - 71.9%) and those with CD4 cell counts >/= 200 cells/microl (14/35 (40.0%), 95%CI 23.8% - 56.2%, P = 0.662). In the 32 subjects who completed the 24-month follow-up, 10 underwent T-SPOT.TB reversion, one had T-SPOT.TB conversion, six remained positive and 15 remained negative. None of them advanced to active tuberculosis during the 36-month follow-up.


CONCLUSIONS
The inactive status of tuberculosis infection may be maintained for a long period in AIDS patients on HAART.
Zhang
Li-fan
LF
Department of Infectious Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China.
Liu
Xiao-qing
XQ
Zuo
Ling-yan
LY
Li
Tai-sheng
TS
Deng
Guo-hua
GH
Wang
Ai-xia
AX
D000163:Acquired Immunodeficiency Syndrome / Q000188:drug therapy* / Q000276:immunology* / Q000382:microbiology; D000328:Adult; D023241:Antiretroviral Therapy, Highly Active; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000472:pathogenicity*; D011446:Prospective Studies; D014376:Tuberculosis / Q000175:diagnosis* / Q000276:immunology
D007371:Interferon-gamma