Quantitative T-cell interferon-gamma responses to Mycobacterium tuberculosis-specific antigens in active and latent tuberculosis.
The objective was to compare the quantitative T-cell responses measured by the commercial interferon-gamma (IFNgamma) release assays (IGRAs) in active and latent tuberculosis (TB) states. T-cell responses of culture-proven TB cases were compared with those of contacts with positive IGRA results and tuberculin skin tests >or= 15 mm. T-SPOT.TB results in 270 active TB cases and 183 community contacts showed the median spot-forming cells (SFCs) above negative control/2.5 x 10(5) peripheral blood mononuclear cells to be 27 (-1 to 203) vs 10 (-2 to 174) in response to ESAT-6 (p < 0.001); and 37 (0 to 293) vs 13 (0 to 225) to CFP-10 (p < 0.001). The median IFNgamma levels (antigen minus nil control) as measured by QuantiFERON-TB Gold In-tube in 270 cases and 142 contacts in congregate settings was 2.3 IU/ml (-0.58 to 31.44) vs 1.7 IU/ml (0.35 to 26.51, p = 0.98). Quantitative T-cell responses as measured by the T-SPOT.TB may indicate mycobacterial burden and disease activity, but cannot be used to discriminate active from latent TB.
Chee
C B E
CB
Singapore Tuberculosis Control Unit, Tan Tock Seng Hospital, Singapore, Singapore. cynthia_chee@ttsh.com.sg
Barkham
T M S
TM
Khinmar
K W
KW
Gan
S H
SH
Wang
Y T
YT
D000942:Antigens, Bacterial / Q000276:immunology*; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods; D007371:Interferon-gamma / Q000378:metabolism*; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*; D014376:Tuberculosis / Q000175:diagnosis* / Q000276:immunology*
D000942:Antigens, Bacterial; D007371:Interferon-gamma