RESUMEN
OBJECTIVE: The quantitative interferon (IFN)-gamma in response to Mycobacterium tuberculosis-specific antigens declines in tuberculosis patients after starting treatment, however, in some cases remains high despite clinical improvements. Our aim was to evaluate clinical parameters associated with remaining QuantiFERON-TB Gold (QFT-G) positive after treatment. METHODS: A prospective cohort study of 101 culture-positive, positive QFT-G, HIV-uninfected patients with pulmonary tuberculosis. QFT-G was performed at diagnosis, at the end of intensive phase, at treatment completion, and 5-7 months post-treatment completion. RESULTS: There were 80 patients with complete results, 34 (43%) remaining QFT-G positive and 46 (58%) reverting to QFT-G negative at the 5-7 month post-treatment time point. There was a significant decline in IFN-gamma levels in response to both CFP-10 and ESAT-6 with tuberculosis treatment. Multivariate analysis revealed significant associations between IFN-gamma levels detected before treatment and remaining QFT-G positive post-treatment after adjustment for smear status, presence of cavitation, and positive sputum culture two months after starting treatment. CONCLUSIONS: Quantitative QFT-G responses drop significantly in active tuberculosis patients undergoing treatment, with almost 60% becoming test negative. Reversion to a negative QFT-G result was closely associated with the magnitude of the IFN-gamma response prior to treatment and increasing age.
Asunto(s)
Interferón gamma/análisis , Mycobacterium tuberculosis/inmunología , Tuberculosis Pulmonar/diagnóstico , Adulto , Factores de Edad , Anciano , Antígenos Bacterianos , Antituberculosos/uso terapéutico , Terapia por Observación Directa , Femenino , Humanos , Japón , Masculino , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa , Estudios Prospectivos , Esputo/microbiología , Resultado del Tratamiento , Tuberculosis Pulmonar/tratamiento farmacológicoRESUMEN
Background. The detection of latent tuberculosis (TB) is essential for TB control, but T-cell assay might be influenced by degree of immunosuppression. The relationship between immunocompetence and interferon (IFN)-γ response in QuantiFERON-TB Gold (QFT) is uncertain, especially in HIV-negative populations. Methods and Results. QFT has been performed for healthy subjects and TB suspected patients. Of 3017 patients, 727 were diagnosed as pulmonary TB by culture. The absolute number of blood lymphocyte in TB patients was significantly associated with QFT. Definitive TB patients were divided into eight groups according to lymphocyte counts. For each subgroup, receiver operating characteristic curve analysis was conducted from 357 healthy control subjects. The optimal cut-off for the patient group with adequate lymphocyte counts was found, but this was reduced for lymphocytopenia. Conclusions. The lymphocyte count was positively associated with QFT. Positive criteria should be calibrated in consideration of cell-mediated immunocompetence and risk of progression to active TB.
RESUMEN
OBJECTIVE: This study evaluated the effect of peripheral lymphocyte count on 2 interferon-gamma release assays [QuantiFERON TB-Gold (QFT-G) and enzyme-linked immunospot (ELISPOT)] and their sensitivity in patients with pulmonary tuberculosis, including HIV-negative immunocompromised patients. PATIENTS AND METHODS: Two hundred thirty patients with microbiologically confirmed active pulmonary tuberculosis were subjected to the tests. Lymphocyte counts were analyzed simultaneously. RESULTS: Overall sensitivity was 74% (159/215; 95% CI, 68-80%) for QFT-G and 92% (198/215; 89-96%) for ELISPOT (p<0.0001). In patients with peripheral lymphocyte counts of > or =1000/microL, sensitivity was high for both QFT-G (88%, 111/126; 82-94%) and ELISPOT (97%, 122/126; 94-100%). However, the sensitivity decreased significantly with decreasing peripheral lymphocyte count for both QFT-G (test for trend p<0.0001) and ELISPOT (test for trend p=0.007). When lymphocyte counts were <500/microL, the sensitivity was 81% (25/31; 66-96%) for ELISPOT, but only 39% (12/31; 21-57%) for QFT-G. CONCLUSION: Both QFT-G and ELISPOT are sensitive methods for detecting active pulmonary tuberculosis, but their sensitivity partly depends on peripheral lymphocyte counts. At low lymphocyte count conditions, ELISPOT is superior to QFT-G for detecting tuberculosis, irrespective of age, gender, and nutrition.