Evaluation of anti-TBGL antibody in the diagnosis of tuberculosis patients in China

Tuberculous glycolipid (TBGL) is a component of the Mycobacterium tuberculosis cell wall, and anti-TBGL antibodies are used for serodiagnosis of tuberculosis. Anti-TBGL IgG and IgA levels were measured in 45 pulmonary TB patients (PTB), 26 extra-pulmonary TB patients (ETB), 16 AIDS-TB patients, and 58 healthy controls (HC) including 39 health care workers (HW) and 19 newly enrolled students (ST). Anti-TBGL IgG measurements yielded 68.9% and 46.2% sensitivity in PTB and ETB, respectively, and 81.0% specificity. However, anti-TBGL IgA measurements were significantly less sensitive in detecting ETB than PTB (15.4% versus 46.7% sensitivity) but showed up to 89.7% specificity. Samples from AIDS-TB patients exhibited low reaction of anti-TBGL IgG and IgA with 6.3% and 12.5% sensitivity, respectively. Unlike anti-lipoarabinomannan (LAM) IgG that was found to elevate in sputum smearpositive subjects, anti-TBGL IgG and IgA elevated in those with cavitation and bronchiectasis, respectively. Anti-TBGL IgG in cavitary TB yielded 78.2% sensitivity compared to 57.1% in those otherwise. Meanwhile, higher anti-TBGL IgA titers were observed in HW than in ST, and increasing anti-TBGL IgG titers were observed in HW on follow-up. Therefore, higher anti-TBGL antibody titers are present in patients presenting cavities and bronchiectasis and subjects under TB exposure risk.