TUBERCULOSIS

Clinical application of a rapid lung-orientated immunoassay in individuals with possible tuberculosis

R A M Breen^1,2, S M Barry^1,2, C J Smith³, R J Shorten⁴, J P Dilworth², I Cropley², T D McHugh⁴, S H Gillespie⁴, G Janossy¹, M C I Lipman²

¹ Department of Immunology, Royal Free and University College Medical School, London, UK
² Departments of Thoracic and HIV Medicine, Royal Free Hospital, London, UK
³ Department of Primary Care and Population Science, Royal Free and University College Medical School, London, UK
⁴ Centre for Medical Microbiology, Royal Free and University College Medical School, London, UK

Dr R A M Breen, Department of Thoracic and HIV Medicine, Royal Free Hospital, London NW3 2QG, UK; r.breen{at}doctors.org.uk

Background: Immunological ex vivo assays to diagnose tuberculosis (TB) have great potential but have largely been blood-based and poorly evaluated in active TB. Lung sampling enables combined microbiological and immunological testing and uses higher frequency antigen-specific responses than in blood.

Methods: A prospective evaluation was undertaken of a flow cytometric assay measuring the percentage of interferon- synthetic CD4+ lymphocytes following stimulation with purified protein derivative of Mycobacterium tuberculosis (PPD) in bronchoalveolar lavage fluid from 250 sputum smear-negative individuals with possible TB. A positive assay was defined as >1.5%.

Results: Of those who underwent lavage and were diagnosed with active TB, 95% (106/111) had a positive immunoassay (95% CI 89% to 98%). In 139 individuals deemed not to have active TB, 105 (76%) were immunoassay negative (95% CI 68% to 82%). Of the remaining 24% (34 cases) with a positive immunoassay, a substantial proportion had evidence of untreated TB; in two of these active TB was subsequently diagnosed. Assay performance was unaffected by HIV status, disease site or BCG vaccination. In culture-positive pulmonary cases, response to PPD was more sensitive than nucleic acid amplification testing (94% vs 73%). The use of early secretory antigen target-6 (ESAT-6) responses in 71 subjects was no better than PPD, and 19% of those with culture-confirmed TB and a positive PPD immunoassay had no detectable response to ESAT-6.

Conclusions: These findings suggest that lung-orientated immunological investigation is a potentially powerful tool in diagnosing individuals with sputum smear-negative active TB, regardless of HIV serostatus.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

• Jafari, C., Thijsen, S., Sotgiu, G., Goletti, D., Benitez, J. A. D., Losi, M., Eberhardt, R., Kirsten, D., Kalsdorf, B., Bossink, A., Latorre, I., Migliori, G. B., Strassburg, A., Winteroll, S., Greinert, U., Richeldi, L., Ernst, M., Lange, C., for the Tuberculosis Network European Trialsgroup, (2009). Bronchoalveolar Lavage Enzyme-linked Immunospot for a Rapid Diagnosis of Tuberculosis: A Tuberculosis Network European Trialsgroup Study. Am. J. Respir. Crit. Care Med. 180: 666-673 [Abstract] [Full Text]  
• Dheda, K, van Zyl-Smit, R N, Meldau, R, Meldau, S, Symons, G, Khalfey, H, Govender, N, Rosu, V, Sechi, L A, Maredza, A, Semple, P, Whitelaw, A, Wainwright, H, Badri, M, Dawson, R, Bateman, E D, Zumla, A (2009). Quantitative lung T cell responses aid the rapid diagnosis of pulmonary tuberculosis. Thorax 64: 847-853 [Abstract] [Full Text]  
• Yew, W. W., Leung, C. C. (2009). Update in Tuberculosis 2008. Am. J. Respir. Crit. Care Med. 179: 337-343 [Full Text]  
• Kim, S.-H., Chu, K., Choi, S.-J., Song, K.-H., Kim, H.-B., Kim, N.-J., Park, S.-H., Yoon, B.-W., Oh, M.-d., Choe, K.-W. (2008). Diagnosis of Central Nervous System Tuberculosis by T-Cell-Based Assays on Peripheral Blood and Cerebrospinal Fluid Mononuclear Cells. CVI 15: 1356-1362 [Abstract] [Full Text]  
• Barry, S., Lipman, M., Breen, R., Janossy, G. (2008). Local immunodiagnosis of pulmonary TB: ELISPOT or flow cytometry, PPD or ESAT-6?. Eur Respir J 32: 531-532 [Full Text]  
• Jafari, C., Ernst, M., Lange, C. (2008). From the authors. Eur Respir J 32: 532-533 [Full Text]  
• Bothamley, G. H (2008). New tests for tuberculosis: local immune responses have greater specificity. Thorax 63: 4-5 [Full Text]