[Clinical usefulness of T-SPOT.TB test for the diagnosis of tuberculosis].
BACKGROUND
Tuberculosis-specific ELISPOT assay (T-SPOT.TB, Oxford Immunotec, UK) is a test that detects interferon-gamma producing T-cells after stimulating patient's lymphocytes with two kinds of tuberculosis-specific antigens (ESAT-6 and CFP-10). We evaluated clinical usefulness of T-SPOT.TB test in Korean adults with intermediate burden of tuberculosis and high rate of BCG vaccination at birth.


METHODS
T-SPOT.TB test was performed in 79 patients and 64 healthy volunteers and these patients and volunteers were classified into four groups: group 1, patients with active tuberculosis (n=30); group 2, patients with not-active tuberculosis (n=27); group 3, patients without tuberculosis (n=24); group 4, healthy volunteers without tuberculosis history (n=62). Positive rates and average spot counts of T-SPOT.TB test were obtained among these groups.


RESULTS
Positive rates of group 1 (96.4%) and group 2 (92.3%) were higher than those of group 3 (31.6%) and group 4 (27.4%) (P<0.0001). The sensitivity deduced from group 1 and specificity deduced from group 4 of T-SPOT.TB test were 96.4% and 72.6%, respectively. The average spot counts of group 1 and 2 were higher than those of group 3 and 4 (P<0.001). There was a tendency of increasing positive rate with increasing age. Overall agreement between T-SPOT.TB test and tuberculin skin test was 63.8% (kappa=0.29).


CONCLUSIONS
T-SPOT.TB test would be a very useful screening and supplementary test for diagnosis of tuberculosis due to its high sensitivity. However, positive results of T-SPOT.TB should be cautiously interpreted because of high positivity in treated tuberculosis patients and healthy volunteers in Korea.
Kim
Hyun Soo
HS
Department of Laboratory Medicine, Hallym University College of Medicine, Seoul, Korea. hskim0901@empal.com
Kim
Cheol Hong
CH
Hur
Mina
M
Hyun
In Gyu
IG
Park
Min Jeong
MJ
Song
Wonkeun
W
Park
Ji Young
JY
Kang
Hee Jung
HJ
Lee
Kyu Man
KM
D000328:Adult; D000368:Aged; D000942:Antigens, Bacterial / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D014376:Tuberculosis / Q000175:diagnosis*
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C117940:CFP-10 protein, Mycobacterium tuberculosis; C093276:ESAT-6 protein, Mycobacterium tuberculosis; D011933:Reagent Kits, Diagnostic; D007371:Interferon-gamma