Waning of the specific interferon-gamma response after years of tuberculosis infection.
OBJECTIVE
Memory T-cell responses to specific antigens wane over time in subjects with tuberculosis (TB) infection.


METHODS
Accumulated evidence indicates that QuantiFERON-TB Gold (QFT-G), a specific whole-blood interferon-gamma (IFN-gamma) based assay, can detect recent TB infections with superior sensitivity and specificity.


OBJECTIVE
We applied this technique to the adult population of a Japanese community to determine its epidemiological usefulness.


METHODS
A total of 1559 subjects attending periodic health screening volunteered to participate in the study.


RESULTS
The QFT-G positive rates were 3.1% for those aged 40-49 years, 5.9% for those aged 50-59 and 9.8% for those aged 60-69. The expected infection prevalence estimated by the authors from a series of studies was 11.1%, 29.6% and 53.1% for those aged 40-49, 50-59 and 60-69 years, respectively. This wide gap between the expected and observed positivity suggests that the IFN-gamma response waned substantially with time after infection. Those with X-rays suggestive of old TB lesions exhibited positivity rates well below 100%.


CONCLUSIONS
The specific IFN-gamma response may wane considerably with time after infection. Longitudinal studies are required to investigate long-term dynamics of cell-mediated immunity in infected donors.
Mori
T
T
Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, Tokyo, Japan. t-mori@nih.go.jp
Harada
N
N
Higuchi
K
K
Sekiya
Y
Y
Uchimura
K
K
Shimao
T
T
D000328:Adult; D000367:Age Factors; D000368:Aged; D000942:Antigens, Bacterial / Q000276:immunology; D001426:Bacterial Proteins / Q000276:immunology; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods; D007156:Immunologic Memory; D007371:Interferon-gamma / Q000032:analysis* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012680:Sensitivity and Specificity; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D014376:Tuberculosis / Q000175:diagnosis / Q000453:epidemiology / Q000276:immunology*
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C117940:CFP-10 protein, Mycobacterium tuberculosis; C093276:ESAT-6 protein, Mycobacterium tuberculosis; D007371:Interferon-gamma