Clinical Evaluation of Anti-Tuberculous Glycolipid Immunoglobulin G Antibody Assay for Rapid Serodiagnosis of Pulmonary Tuberculosis

Abstract

Previously we reported the development of a highly sensitive enzyme-linked immunosorbent assay specific for anti-tuberculous glycolipid (anti-TBGL) for the rapid serodiagnosis of tuberculosis. In this study, the usefulness of an anti-TBGL antibody assay kit for rapid serodiagnosis was evaluated in a controlled multicenter study. Antibody titers in sera from 318 patients with active pulmonary tuberculosis (216 positive for Mycobacterium tuberculosis in smear and/or culture tests and 102 smear and culture negative and clinically diagnosed), 58 patients with old tuberculosis, 177 patients with other respiratory diseases, 156 patients with nonrespiratory diseases, and 454 healthy subjects were examined. Sera from 256 younger healthy subjects from among the 454 healthy subjects were examined as a control. When the cutoff point of anti-TBGL antibody titer was determined as 2.0 U/ml, the sensitivity for active tuberculosis patients was 81.1% and the specificity was 95.7%. Sensitivity in patients with smear-negative and culture-negative active pulmonary tuberculosis was 73.5%. Even in patients with noncavitary minimally advanced lesions, the positivity rate (60.0%) and the antibody titer (4.6 ؎ 9.4 U/ml) were significantly higher than those in the healthy group. These results indicate that this assay using anti-TBGL antibody is useful for the rapid serodiagnosis of active pulmonary tuberculosis.To eradicate tuberculosis, it is important to improve diagnostic techniques so that active tuberculosis can be treated at an early stage before tuberculous bacilli can be detected in the sputa. The tuberculin skin test is not useful in subjects with a previous history of active tuberculosis or Mycobacterium bovis BCG vaccination. Gene technology utilizing nucleic acid amplification has been successfully introduced for rapid diagnosis of pulmonary tuberculosis. Clinically, however, its usefulness is reduced in patients without sputum expectoration. In fact, in previous papers, including a report of the American Thoracic Society (ATS) Workshop in 1997, the sensitivity of gene diagnosis was reported to be about 50% in patients with acid-fast bacillus smear-negative pulmonary tuberculosis (4, 6, 8) and was particularly low (5 to 20%) in smear and culture-negative patients with active pulmonary tuberculosis (5, 12). A further drawback is that this test is expensive. Therefore, there has been strong demand for the development of rapid, reliable, and less costly diagnostic methods for the detection of pulmonary tuberculosis.We previously developed an enzyme immunoassay in which the glycolipid antigen trehalose 6,6Ј-dimycolate (TDM) purified from Mycobacterium tuberculosis H37Rv was used as an antigen for detecting antituberculosis immunoglobulins and showed that a glycolipid was an effective antigen for serodiagnosis (13, 16). Subsequently, by mixing TDM with more hydrophilic glycolipids, we constructed a new tuberculous glycolipid (TBGL) antigen and successfully established a sensitive serodiagnostic kit for tuberculosis using this ant...

Increased Synthesis of Anti-Tuberculous Glycolipid Immunoglobulin G (IgG) and IgA with Cavity Formation in Patients with Pulmonary Tuberculosis

“…The remaining 30 patients were excluded for the following reasons: 4 for both negative culture and a negative PCR test for Mycobacterium tuberculosis in sputum, 5 for more than 2 weeks of TB treatment, 2 for Mycobacterium avium complex infection, 4 for HIV infection, 3 for malignancy, 2 for interstitial pneumonia, and 10 for insufficient data collection. We enrolled patients with less than 2 weeks of treatment based on a report that anti-TBGL IgG did not decrease until 1 month after the commencement of chemotherapy (15). The study was approved by the Ethics Committee of Tokyo Metropolitan Fuchu Hospital.…”

“…We compared all the measured laboratory markers between the patients with cavitary lesions (cavity ϩ group) and those without cavitary lesions (cavity Ϫ group) in order to determine new differences apart from that of the anti-TBGL IgG level (15). As shown in Table 2, both anti-TBGL IgG and anti-TBGL IgA levels were significantly higher in the cavity ϩ group (P Ͻ 0.005 and P Ͻ 0.05, respectively), but the anti-TBGL IgM titers showed no difference between the two groups.…”

“…Furthermore, it was reported that the positive rate and the titers of anti-TBGL IgG were higher in pulmonary TB patients with cavitary lesions than in those without cavitary lesions (15). Considering this result, we subdivided the patients into two groups, those with cavitary lesions (cavity ϩ group) and those without cavitary lesions (cavity Ϫ group), and compared multiple laboratory markers to determine associations.…”

Nonconventional and new methods in the diagnosis of tuberculosis: feasibility and applicability in the field

“…Different types of blood tests have been proposed for serologic diagnosis of TB [5,104,105]. The first studies using partially purified antigens allowed the detection of anti-mycobacterial antibodies in TB patients, but the tests showed poor specificity [106].…”

Immunological Diagnosis of Active and Latent TB

“…By combining TDM with more hydrophobic glycolipids, a new tuberculous glycolipid (TBGL) antigen was designed and a more sensitive serodiagnostic kit for TB, an anti-TBGL IgG test was developed (Kyowa Medex Co, Japan). Anti-TBGL IgG antibody (TBGL IgG) has been proposed as a useful serodiagnostic marker of active pulmonary tuberculosis (PTB) (sensitivity: 84% and specificity: 95% in young adults) in Japan (Maekura et al, 2001). Strong association between TBGL IgG and IgA was also revealed in active pulmonary tuberculosis cases and increased TBGL IgG and IgA was found to be associated with CRP and cavity formation indicating their involvement in the disease pathogenesis (Mizusawa et al, 2008).…”