Do results of the T-SPOT.TB interferon-gamma release assay change after treatment of tuberculosis?
BACKGROUND
Interferon-gamma (IFN-gamma) production by lymphocytes exposed to antigens specific of Mycobacterium tuberculosis has been shown to correlate with antigen load and disease activity.


OBJECTIVE
To determine whether treatment of tuberculosis (TB) led to a decrease and/or a reversion of results of a IFN-gamma release assay (T-SPOT.TB, Oxford Immunotec, UK) and thus if T-SPOT.TB could be used to monitor response to treatment.


METHODS
Qualitative and quantitative analysis (SFUs: spot-forming units) of T-SPOT.TB in HIV-negative patients with TB, during initial 2 weeks of treatment (T0), at end of treatment (TE) and 6 months later (TE+6).


RESULTS
Mean SFU (SD) was 75 (58; n=62) at T0, 46 (55; n=55) at TE, and 33 (46; n=41) at TE+6; positive rate was 98%, 93% and 98%, respectively. SFUs (paired samples, n=36) decreased significantly between T0 and TE; 2 reversions occurred between T0 and TE (6%), but none between TE and TE+6. Of 6 patients (17%) with an increase in SFUs between T0 and TE, 5 had a favourable outcome at TE and TE+6.


CONCLUSIONS
Decrease in SFUs under treatment suggests a relationship with antigen load; however, persisting high SFUs were not predictive of unfavourable outcome and test reversion was rare.
Bosshard
Valerie
V
Division of Pulmonary Diseases, Geneva University Hospital, 1211 Geneva 14, Switzerland.
Roux-Lombard
Pascale
P
Perneger
Thomas
T
Metzger
Marie
M
Vivien
Regis
R
Rochat
Thierry
T
Janssens
Jean-Paul
JP
D000328:Adult; D000937:Antigen-Antibody Reactions; D000941:Antigens; D000942:Antigens, Bacterial; D000995:Antitubercular Agents / Q000627:therapeutic use; D001426:Bacterial Proteins; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000032:analysis* / Q000378:metabolism; D008214:Lymphocytes / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D011446:Prospective Studies; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D013997:Time Factors; D016896:Treatment Outcome; D014376:Tuberculosis / Q000175:diagnosis* / Q000188:drug therapy*
D000941:Antigens; D000942:Antigens, Bacterial; D000995:Antitubercular Agents; D001426:Bacterial Proteins; C117940:CFP-10 protein, Mycobacterium tuberculosis; C093276:ESAT-6 protein, Mycobacterium tuberculosis; D011933:Reagent Kits, Diagnostic; D007371:Interferon-gamma