Gamma Interferon Immunospot Assay of Pleural Effusion Mononuclear Cells for Diagnosis of Tuberculous Pleurisy

Abstract

e Diagnosis of tuberculous pleurisy remains a challenge in the clinic. In this study, we evaluated the usefulness of a previously developed Mycobacterium tuberculosis antigen-specific gamma interferon enzyme-linked immunospot (ELISPOT) assay in the diagnosis of tuberculous pleurisy by testing a cohort of 352 patients with pleural effusion. We found that M. tuberculosis antigen-specific gamma interferon-producing cells were enriched four to five times in pleural fluid compared with their levels in peripheral blood from patients with tuberuclous pleurisy assayed in parallel. The sensitivity, specificity, positive predictive value, and negative predictive value of the pleural fluid mononuclear cell ELISPOT assay for the diagnosis of tuberculous pleurisy were 95.7%, 100%, 100%, and 81.0%, respectively. In comparison, the sensitivity and specificity of the ELISPOT assay using peripheral blood mononuclear cells were 78.3% and 86.3%, respectively. The sensitivity and specificity of the pleural fluid adenosine deaminase activity test were 55.5% and 86.3%, respectively. These results demonstrate that the M. tuberculosis antigen-specific ELISPOT assay performed on pleural fluid mononuclear cells provides an accurate, rapid diagnosis of tuberculous pleurisy.T uberculosis (TB) is a leading cause of morbidity and mortality throughout the world, with 95% of cases and 97% of all deaths occurring in high-prevalence countries such as China, where the prevalence of active TB is as high as 367/100,000 population (1). Tuberculous pleurisy (TBP) is a common clinical manifestation of active TB disease and may account for up to 50% of all pleural effusions in areas with a high incidence of TB (2). Standard diagnostic assays for TBP, including microbiological examination, adenosine deaminase (ADA) levels, cell infiltrate profile, and certain other biochemical tests, do not provide satisfactory sensitivity and specificity (3). As an example, ADA determination has been recognized as a relatively sensitive diagnostic test for TBP; increased ADA levels are observed in a number of other diseases, such as parapneumonic effusions and noninfectious inflammatory diseases (4). High pleural fluid ADA levels do not necessarily indicate the presence of TBP, especially when pleural fluid potassium levels exceed 5.0 mEq/liter (5).Infection with Mycobacterium tuberculosis elicits a strong antigen-specific gamma interferon (IFN-␥) response from host T cells, which is used as an indicator to diagnose latent M. tuberculosis infection in clinical practice (6, 7). In addition, we and others have applied the M. tuberculosis antigen-specific IFN-␥ enzymelinked immunosorbent spot (ELISPOT) assay to peripheral blood mononuclear cells (PBMC) to diagnose active TB (8, 9). Although the sensitivity of the peripheral blood ELISPOT assay for the diagnosis of active pulmonary TB is significantly higher than those of routine tests such as sputum M. tuberculosis culture, the specificity is not satisfactory, mostly due to its inability to discriminate active TB disease ...

Accuracy of enzyme-linked immunospot assay for diagnosis of pleural tuberculosis: a meta-analysis

“…The full text of the remaining 10 articles was examined, and one study (Losi et al, 2010) was excluded because it did not use the t-spot assay format. The final meta-analysis therefore included nine publications (Losi et al, 2007;Lee et al, 2009;Dheda et al, 2009;Kang et al, 2012;Keng et al, 2013;Liao et al, 2014;Zhang et al, 2014;Liu et al, 2013Liu et al, , 2014 TN = truly negative result; TP = truly positive result; FN = false-negative result; FP = false-positive result. a Enzymelinked immunospot assay (T-SPOT-TB; Oxford Immunotec Ltd., Oxford, UK) measuring the immune response to an ESAT-6 or CFP-10 peptide.…”

“…Despite extensive research on this assay, its diagnostic accuracy remains controversial. For example, one study reported a sensitivity of 95.7% and a specificity of 100% (Liao et al, 2014), while another study reported corresponding values of only 86 and 60% (Dheda et al, 2009). Since these accuracy studies were carried out with diverse sample sizes, patients of different ethnicities, and differing technical parameters (such as detection cut-offs), we wanted to assess the available evidence as rigorously and comprehensively as possible.…”

IP-10 and MIG Are Compartmentalized at the Site of Disease during Pleural and Meningeal Tuberculosis and Are Decreased after Antituberculosis Treatment

“…Due to the shortage of available methods for diagnosis of TB, IGRAs have increasingly been used as an auxiliary diagnostic tool for active TB in clinical practice in China (18,(31)(32)(33). Indeed, it has been reported that detection of IFN-␥ in pleural fluid mononuclear cells is useful for diagnosis of tuberculous pleurisy (31,32).…”

“…Indeed, it has been reported that detection of IFN-␥ in pleural fluid mononuclear cells is useful for diagnosis of tuberculous pleurisy (31,32). Additionally, IGRAs have improved the sensitivity for diagnosis of pulmonary TB (18), pediatric TB (34), and osteoarticular TB (33).…”

Pleural Fluid and Tuberculosis: Are All Interferon Gamma Release Assays Equal?

“…In this discussion, we would like to emphasize two additional items. We point the authors to another important study regarding this topic, which, as far as we know, was not included in their review (4). In addition, Aggarwal et al (1) appropriately describe that false positives may have compromised the specificity due to latent TB in non-TPE patients.…”