Korean J Lab Med.  2010 Apr;30(2):171-177. 10.3343/kjlm.2010.30.2.171.

Clinical Usefulness of T-SPOT.TB Test for the Diagnosis of Tuberculosis

• Kim HS
• Kim CH
• Hur M
• Hyun IG
• Park MJ
• Song W
• Park JY
• Kang HJ
• Lee KM

• KMID: 1096804
• DOI: http://doi.org/10.3343/kjlm.2010.30.2.171

Abstract

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.

Keyword

Tuberculosis; Interferon-gamma; ELISPOT

MeSH Terms

Adult
Aged
Antigens, Bacterial/metabolism
Bacterial Proteins/metabolism
*Enzyme-Linked Immunosorbent Assay
Female
Humans
Interferon-gamma/metabolism
Male
Middle Aged
Reagent Kits, Diagnostic
Sensitivity and Specificity
T-Lymphocytes/immunology/metabolism
Tuberculosis/*diagnosis

Figure

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  Fig. 1. The number of spot-forming cells of T-SPOT.TB test in the different groups of patients and healthy volunteers.

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  Fig. 2. Correlation of tuberculin skin test (TST) results with T-SPOT. TB results in patients and healthy volunteers.

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